Post on 19-Dec-2015
transcript
12 1
Victor S FrostDan F Servey Distinguished Professor Electrical Engineering and Computer
ScienceUniversity of Kansas2335 Irving Hill Dr
Lawrence Kansas 66045Phone (785) 864-4833 FAX(785) 864-
7789 e-mail frosteecskuedu
httpwwwittckuedu
Specific Systems
CellularPart 112
All material copyright 2006Victor S Frost All Rights Reserved
12 2
Outline
bull Part 1ndash Basic componentsndash 3G ndash Overview of W-CDMAUMTSndash HSPDA
bull Part 2ndash EV-DO overviewndash Case study Mitigating scheduler-
induced starvation in 3G wireless networks
12 3
AC = authentication center BSS = base station subsystem EIR = equipment identity register HLR = home location register
Wirelineterminal
MSC
PSTN
BSS BSS
STP SS7HLRVLR
EIRAC
MSC = mobile switching centerPSTN = public switched telephone network STP = signal transfer point VLR = visitor location register
Cellular Network Physical Topology
Base stationbull Transmits to users on
forward channelsbull Receives from users
on reverse channels
Mobile Switching Center
bull Controls connection setup within cells amp to telephone network
I nternetInternet
Modified from Leon-Garcia amp Widjaja Communication Networks
Mobile Stations
12 4
Components
bull Mobile stations (MS)ndash TransmitReceive over the air interface
bull Signalingbull User information
ndash Voicendash Internetndash Video
ndash Will set up multiple ldquochannelsrdquo for communication
bull SignalingControlndash Set up and maintain callsndash Establish relationship between mobile unit and
nearest BSbull User voicedata channels traffic channels
12 5
Components
bull Base station (BS)ndash TransmitReceive over the air
interface to multiple mobile stationsndash Terminates radio signals ndash Packages information for transport to
a controller (MSC) for routingndash Sends information to Mobile Switching
Center
12 6
Components
bull Mobile Switching Center (MSC)ndash Connects to many BSsndash Performs call set upndash Provides routing functionsndash Typically associated with voice callsndash Sometines called Mobile Telecommunications Switching Office
(MST0)bull Home location register (HLR)
ndash Wireless service provider (WSP) maintains a databasebull Subscriber personal information eg phone number mobile
identification number electronic serial number (ESN) of phone bull Service Profilebull Current location of subscriber
ndash One HLR may serve several MSCsbull Visitor location register (VLR)
ndash Data base containing temporary information of subscribersndash For subscribers away from home service areandash VRL information retrieved from the HLR
12 7
Process
bull Registrationndash Turn on cell phonendash BS continually transmit
signals on control channelsndash Cell phone scans for
strongest signalndash Cell phone decodes control
signal to determinebull System Idbull Initial Tx power settingbull Radio channels to use for
further communicationsbull Cell phone registers with
network bull Note as the MS moves it
may need to cancel registration in old area and re-register in new area
12 8
Process
bull Mobile Call Initiationndash To make a call the
mobile keys the phone and hits send
ndash Phone transmitted over preselected control channel
ndash The BS relays information to the MSC
ndash MSC looking into the control message to get the and processes the call ie does the routing
12 9
Process
bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to
determine location of subscriber
ndash MSC has current visiting MSC stored in the HLR
ndash Home MSC communicates with the visiting MSC to rout the call
ndash The MSC sends a paging message to the paging message to BS
ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel
12 10
Process
bull Call acceptedndash MS sees the paging
signal and responds to the BS
ndash The BS send response to the MSC
ndash The MSC sets up the call to the BS
ndash The MSC also assigns a air interface channel for the BS to use for the call
ndash The MS communicates of the assigned channel
bull Here the call is between two mobiles
bull The communications is monitored for the ongoing call
12 11
Processbull Handoff (or handover)
ndash MS continually scans for control signals of BS
ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold
ndash Upon that event the MSC will initiate a handoff procedure
ndash Handoff procedures can be implemented transparent to the users no interruption
ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS
12 12
Process
bull Handoffsndash Hard communications with old BS is terminated and
a new communications to a new BS is establishedndash Soft
bull Soft mobile station temporarily connected to more than one base station simultaneously
bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously
bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously
bull Provides diversitybull Occurs at boundaries of sectorscells
12 13
Other Functions
bull Call blockingndash if all traffic channels busy
bull Call terminationndash when user hangs up
bull Call dropndash when BS cannot maintain required signal
strength
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 2
Outline
bull Part 1ndash Basic componentsndash 3G ndash Overview of W-CDMAUMTSndash HSPDA
bull Part 2ndash EV-DO overviewndash Case study Mitigating scheduler-
induced starvation in 3G wireless networks
12 3
AC = authentication center BSS = base station subsystem EIR = equipment identity register HLR = home location register
Wirelineterminal
MSC
PSTN
BSS BSS
STP SS7HLRVLR
EIRAC
MSC = mobile switching centerPSTN = public switched telephone network STP = signal transfer point VLR = visitor location register
Cellular Network Physical Topology
Base stationbull Transmits to users on
forward channelsbull Receives from users
on reverse channels
Mobile Switching Center
bull Controls connection setup within cells amp to telephone network
I nternetInternet
Modified from Leon-Garcia amp Widjaja Communication Networks
Mobile Stations
12 4
Components
bull Mobile stations (MS)ndash TransmitReceive over the air interface
bull Signalingbull User information
ndash Voicendash Internetndash Video
ndash Will set up multiple ldquochannelsrdquo for communication
bull SignalingControlndash Set up and maintain callsndash Establish relationship between mobile unit and
nearest BSbull User voicedata channels traffic channels
12 5
Components
bull Base station (BS)ndash TransmitReceive over the air
interface to multiple mobile stationsndash Terminates radio signals ndash Packages information for transport to
a controller (MSC) for routingndash Sends information to Mobile Switching
Center
12 6
Components
bull Mobile Switching Center (MSC)ndash Connects to many BSsndash Performs call set upndash Provides routing functionsndash Typically associated with voice callsndash Sometines called Mobile Telecommunications Switching Office
(MST0)bull Home location register (HLR)
ndash Wireless service provider (WSP) maintains a databasebull Subscriber personal information eg phone number mobile
identification number electronic serial number (ESN) of phone bull Service Profilebull Current location of subscriber
ndash One HLR may serve several MSCsbull Visitor location register (VLR)
ndash Data base containing temporary information of subscribersndash For subscribers away from home service areandash VRL information retrieved from the HLR
12 7
Process
bull Registrationndash Turn on cell phonendash BS continually transmit
signals on control channelsndash Cell phone scans for
strongest signalndash Cell phone decodes control
signal to determinebull System Idbull Initial Tx power settingbull Radio channels to use for
further communicationsbull Cell phone registers with
network bull Note as the MS moves it
may need to cancel registration in old area and re-register in new area
12 8
Process
bull Mobile Call Initiationndash To make a call the
mobile keys the phone and hits send
ndash Phone transmitted over preselected control channel
ndash The BS relays information to the MSC
ndash MSC looking into the control message to get the and processes the call ie does the routing
12 9
Process
bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to
determine location of subscriber
ndash MSC has current visiting MSC stored in the HLR
ndash Home MSC communicates with the visiting MSC to rout the call
ndash The MSC sends a paging message to the paging message to BS
ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel
12 10
Process
bull Call acceptedndash MS sees the paging
signal and responds to the BS
ndash The BS send response to the MSC
ndash The MSC sets up the call to the BS
ndash The MSC also assigns a air interface channel for the BS to use for the call
ndash The MS communicates of the assigned channel
bull Here the call is between two mobiles
bull The communications is monitored for the ongoing call
12 11
Processbull Handoff (or handover)
ndash MS continually scans for control signals of BS
ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold
ndash Upon that event the MSC will initiate a handoff procedure
ndash Handoff procedures can be implemented transparent to the users no interruption
ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS
12 12
Process
bull Handoffsndash Hard communications with old BS is terminated and
a new communications to a new BS is establishedndash Soft
bull Soft mobile station temporarily connected to more than one base station simultaneously
bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously
bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously
bull Provides diversitybull Occurs at boundaries of sectorscells
12 13
Other Functions
bull Call blockingndash if all traffic channels busy
bull Call terminationndash when user hangs up
bull Call dropndash when BS cannot maintain required signal
strength
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 3
AC = authentication center BSS = base station subsystem EIR = equipment identity register HLR = home location register
Wirelineterminal
MSC
PSTN
BSS BSS
STP SS7HLRVLR
EIRAC
MSC = mobile switching centerPSTN = public switched telephone network STP = signal transfer point VLR = visitor location register
Cellular Network Physical Topology
Base stationbull Transmits to users on
forward channelsbull Receives from users
on reverse channels
Mobile Switching Center
bull Controls connection setup within cells amp to telephone network
I nternetInternet
Modified from Leon-Garcia amp Widjaja Communication Networks
Mobile Stations
12 4
Components
bull Mobile stations (MS)ndash TransmitReceive over the air interface
bull Signalingbull User information
ndash Voicendash Internetndash Video
ndash Will set up multiple ldquochannelsrdquo for communication
bull SignalingControlndash Set up and maintain callsndash Establish relationship between mobile unit and
nearest BSbull User voicedata channels traffic channels
12 5
Components
bull Base station (BS)ndash TransmitReceive over the air
interface to multiple mobile stationsndash Terminates radio signals ndash Packages information for transport to
a controller (MSC) for routingndash Sends information to Mobile Switching
Center
12 6
Components
bull Mobile Switching Center (MSC)ndash Connects to many BSsndash Performs call set upndash Provides routing functionsndash Typically associated with voice callsndash Sometines called Mobile Telecommunications Switching Office
(MST0)bull Home location register (HLR)
ndash Wireless service provider (WSP) maintains a databasebull Subscriber personal information eg phone number mobile
identification number electronic serial number (ESN) of phone bull Service Profilebull Current location of subscriber
ndash One HLR may serve several MSCsbull Visitor location register (VLR)
ndash Data base containing temporary information of subscribersndash For subscribers away from home service areandash VRL information retrieved from the HLR
12 7
Process
bull Registrationndash Turn on cell phonendash BS continually transmit
signals on control channelsndash Cell phone scans for
strongest signalndash Cell phone decodes control
signal to determinebull System Idbull Initial Tx power settingbull Radio channels to use for
further communicationsbull Cell phone registers with
network bull Note as the MS moves it
may need to cancel registration in old area and re-register in new area
12 8
Process
bull Mobile Call Initiationndash To make a call the
mobile keys the phone and hits send
ndash Phone transmitted over preselected control channel
ndash The BS relays information to the MSC
ndash MSC looking into the control message to get the and processes the call ie does the routing
12 9
Process
bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to
determine location of subscriber
ndash MSC has current visiting MSC stored in the HLR
ndash Home MSC communicates with the visiting MSC to rout the call
ndash The MSC sends a paging message to the paging message to BS
ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel
12 10
Process
bull Call acceptedndash MS sees the paging
signal and responds to the BS
ndash The BS send response to the MSC
ndash The MSC sets up the call to the BS
ndash The MSC also assigns a air interface channel for the BS to use for the call
ndash The MS communicates of the assigned channel
bull Here the call is between two mobiles
bull The communications is monitored for the ongoing call
12 11
Processbull Handoff (or handover)
ndash MS continually scans for control signals of BS
ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold
ndash Upon that event the MSC will initiate a handoff procedure
ndash Handoff procedures can be implemented transparent to the users no interruption
ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS
12 12
Process
bull Handoffsndash Hard communications with old BS is terminated and
a new communications to a new BS is establishedndash Soft
bull Soft mobile station temporarily connected to more than one base station simultaneously
bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously
bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously
bull Provides diversitybull Occurs at boundaries of sectorscells
12 13
Other Functions
bull Call blockingndash if all traffic channels busy
bull Call terminationndash when user hangs up
bull Call dropndash when BS cannot maintain required signal
strength
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 4
Components
bull Mobile stations (MS)ndash TransmitReceive over the air interface
bull Signalingbull User information
ndash Voicendash Internetndash Video
ndash Will set up multiple ldquochannelsrdquo for communication
bull SignalingControlndash Set up and maintain callsndash Establish relationship between mobile unit and
nearest BSbull User voicedata channels traffic channels
12 5
Components
bull Base station (BS)ndash TransmitReceive over the air
interface to multiple mobile stationsndash Terminates radio signals ndash Packages information for transport to
a controller (MSC) for routingndash Sends information to Mobile Switching
Center
12 6
Components
bull Mobile Switching Center (MSC)ndash Connects to many BSsndash Performs call set upndash Provides routing functionsndash Typically associated with voice callsndash Sometines called Mobile Telecommunications Switching Office
(MST0)bull Home location register (HLR)
ndash Wireless service provider (WSP) maintains a databasebull Subscriber personal information eg phone number mobile
identification number electronic serial number (ESN) of phone bull Service Profilebull Current location of subscriber
ndash One HLR may serve several MSCsbull Visitor location register (VLR)
ndash Data base containing temporary information of subscribersndash For subscribers away from home service areandash VRL information retrieved from the HLR
12 7
Process
bull Registrationndash Turn on cell phonendash BS continually transmit
signals on control channelsndash Cell phone scans for
strongest signalndash Cell phone decodes control
signal to determinebull System Idbull Initial Tx power settingbull Radio channels to use for
further communicationsbull Cell phone registers with
network bull Note as the MS moves it
may need to cancel registration in old area and re-register in new area
12 8
Process
bull Mobile Call Initiationndash To make a call the
mobile keys the phone and hits send
ndash Phone transmitted over preselected control channel
ndash The BS relays information to the MSC
ndash MSC looking into the control message to get the and processes the call ie does the routing
12 9
Process
bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to
determine location of subscriber
ndash MSC has current visiting MSC stored in the HLR
ndash Home MSC communicates with the visiting MSC to rout the call
ndash The MSC sends a paging message to the paging message to BS
ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel
12 10
Process
bull Call acceptedndash MS sees the paging
signal and responds to the BS
ndash The BS send response to the MSC
ndash The MSC sets up the call to the BS
ndash The MSC also assigns a air interface channel for the BS to use for the call
ndash The MS communicates of the assigned channel
bull Here the call is between two mobiles
bull The communications is monitored for the ongoing call
12 11
Processbull Handoff (or handover)
ndash MS continually scans for control signals of BS
ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold
ndash Upon that event the MSC will initiate a handoff procedure
ndash Handoff procedures can be implemented transparent to the users no interruption
ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS
12 12
Process
bull Handoffsndash Hard communications with old BS is terminated and
a new communications to a new BS is establishedndash Soft
bull Soft mobile station temporarily connected to more than one base station simultaneously
bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously
bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously
bull Provides diversitybull Occurs at boundaries of sectorscells
12 13
Other Functions
bull Call blockingndash if all traffic channels busy
bull Call terminationndash when user hangs up
bull Call dropndash when BS cannot maintain required signal
strength
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 5
Components
bull Base station (BS)ndash TransmitReceive over the air
interface to multiple mobile stationsndash Terminates radio signals ndash Packages information for transport to
a controller (MSC) for routingndash Sends information to Mobile Switching
Center
12 6
Components
bull Mobile Switching Center (MSC)ndash Connects to many BSsndash Performs call set upndash Provides routing functionsndash Typically associated with voice callsndash Sometines called Mobile Telecommunications Switching Office
(MST0)bull Home location register (HLR)
ndash Wireless service provider (WSP) maintains a databasebull Subscriber personal information eg phone number mobile
identification number electronic serial number (ESN) of phone bull Service Profilebull Current location of subscriber
ndash One HLR may serve several MSCsbull Visitor location register (VLR)
ndash Data base containing temporary information of subscribersndash For subscribers away from home service areandash VRL information retrieved from the HLR
12 7
Process
bull Registrationndash Turn on cell phonendash BS continually transmit
signals on control channelsndash Cell phone scans for
strongest signalndash Cell phone decodes control
signal to determinebull System Idbull Initial Tx power settingbull Radio channels to use for
further communicationsbull Cell phone registers with
network bull Note as the MS moves it
may need to cancel registration in old area and re-register in new area
12 8
Process
bull Mobile Call Initiationndash To make a call the
mobile keys the phone and hits send
ndash Phone transmitted over preselected control channel
ndash The BS relays information to the MSC
ndash MSC looking into the control message to get the and processes the call ie does the routing
12 9
Process
bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to
determine location of subscriber
ndash MSC has current visiting MSC stored in the HLR
ndash Home MSC communicates with the visiting MSC to rout the call
ndash The MSC sends a paging message to the paging message to BS
ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel
12 10
Process
bull Call acceptedndash MS sees the paging
signal and responds to the BS
ndash The BS send response to the MSC
ndash The MSC sets up the call to the BS
ndash The MSC also assigns a air interface channel for the BS to use for the call
ndash The MS communicates of the assigned channel
bull Here the call is between two mobiles
bull The communications is monitored for the ongoing call
12 11
Processbull Handoff (or handover)
ndash MS continually scans for control signals of BS
ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold
ndash Upon that event the MSC will initiate a handoff procedure
ndash Handoff procedures can be implemented transparent to the users no interruption
ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS
12 12
Process
bull Handoffsndash Hard communications with old BS is terminated and
a new communications to a new BS is establishedndash Soft
bull Soft mobile station temporarily connected to more than one base station simultaneously
bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously
bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously
bull Provides diversitybull Occurs at boundaries of sectorscells
12 13
Other Functions
bull Call blockingndash if all traffic channels busy
bull Call terminationndash when user hangs up
bull Call dropndash when BS cannot maintain required signal
strength
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 6
Components
bull Mobile Switching Center (MSC)ndash Connects to many BSsndash Performs call set upndash Provides routing functionsndash Typically associated with voice callsndash Sometines called Mobile Telecommunications Switching Office
(MST0)bull Home location register (HLR)
ndash Wireless service provider (WSP) maintains a databasebull Subscriber personal information eg phone number mobile
identification number electronic serial number (ESN) of phone bull Service Profilebull Current location of subscriber
ndash One HLR may serve several MSCsbull Visitor location register (VLR)
ndash Data base containing temporary information of subscribersndash For subscribers away from home service areandash VRL information retrieved from the HLR
12 7
Process
bull Registrationndash Turn on cell phonendash BS continually transmit
signals on control channelsndash Cell phone scans for
strongest signalndash Cell phone decodes control
signal to determinebull System Idbull Initial Tx power settingbull Radio channels to use for
further communicationsbull Cell phone registers with
network bull Note as the MS moves it
may need to cancel registration in old area and re-register in new area
12 8
Process
bull Mobile Call Initiationndash To make a call the
mobile keys the phone and hits send
ndash Phone transmitted over preselected control channel
ndash The BS relays information to the MSC
ndash MSC looking into the control message to get the and processes the call ie does the routing
12 9
Process
bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to
determine location of subscriber
ndash MSC has current visiting MSC stored in the HLR
ndash Home MSC communicates with the visiting MSC to rout the call
ndash The MSC sends a paging message to the paging message to BS
ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel
12 10
Process
bull Call acceptedndash MS sees the paging
signal and responds to the BS
ndash The BS send response to the MSC
ndash The MSC sets up the call to the BS
ndash The MSC also assigns a air interface channel for the BS to use for the call
ndash The MS communicates of the assigned channel
bull Here the call is between two mobiles
bull The communications is monitored for the ongoing call
12 11
Processbull Handoff (or handover)
ndash MS continually scans for control signals of BS
ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold
ndash Upon that event the MSC will initiate a handoff procedure
ndash Handoff procedures can be implemented transparent to the users no interruption
ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS
12 12
Process
bull Handoffsndash Hard communications with old BS is terminated and
a new communications to a new BS is establishedndash Soft
bull Soft mobile station temporarily connected to more than one base station simultaneously
bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously
bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously
bull Provides diversitybull Occurs at boundaries of sectorscells
12 13
Other Functions
bull Call blockingndash if all traffic channels busy
bull Call terminationndash when user hangs up
bull Call dropndash when BS cannot maintain required signal
strength
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 7
Process
bull Registrationndash Turn on cell phonendash BS continually transmit
signals on control channelsndash Cell phone scans for
strongest signalndash Cell phone decodes control
signal to determinebull System Idbull Initial Tx power settingbull Radio channels to use for
further communicationsbull Cell phone registers with
network bull Note as the MS moves it
may need to cancel registration in old area and re-register in new area
12 8
Process
bull Mobile Call Initiationndash To make a call the
mobile keys the phone and hits send
ndash Phone transmitted over preselected control channel
ndash The BS relays information to the MSC
ndash MSC looking into the control message to get the and processes the call ie does the routing
12 9
Process
bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to
determine location of subscriber
ndash MSC has current visiting MSC stored in the HLR
ndash Home MSC communicates with the visiting MSC to rout the call
ndash The MSC sends a paging message to the paging message to BS
ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel
12 10
Process
bull Call acceptedndash MS sees the paging
signal and responds to the BS
ndash The BS send response to the MSC
ndash The MSC sets up the call to the BS
ndash The MSC also assigns a air interface channel for the BS to use for the call
ndash The MS communicates of the assigned channel
bull Here the call is between two mobiles
bull The communications is monitored for the ongoing call
12 11
Processbull Handoff (or handover)
ndash MS continually scans for control signals of BS
ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold
ndash Upon that event the MSC will initiate a handoff procedure
ndash Handoff procedures can be implemented transparent to the users no interruption
ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS
12 12
Process
bull Handoffsndash Hard communications with old BS is terminated and
a new communications to a new BS is establishedndash Soft
bull Soft mobile station temporarily connected to more than one base station simultaneously
bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously
bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously
bull Provides diversitybull Occurs at boundaries of sectorscells
12 13
Other Functions
bull Call blockingndash if all traffic channels busy
bull Call terminationndash when user hangs up
bull Call dropndash when BS cannot maintain required signal
strength
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 8
Process
bull Mobile Call Initiationndash To make a call the
mobile keys the phone and hits send
ndash Phone transmitted over preselected control channel
ndash The BS relays information to the MSC
ndash MSC looking into the control message to get the and processes the call ie does the routing
12 9
Process
bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to
determine location of subscriber
ndash MSC has current visiting MSC stored in the HLR
ndash Home MSC communicates with the visiting MSC to rout the call
ndash The MSC sends a paging message to the paging message to BS
ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel
12 10
Process
bull Call acceptedndash MS sees the paging
signal and responds to the BS
ndash The BS send response to the MSC
ndash The MSC sets up the call to the BS
ndash The MSC also assigns a air interface channel for the BS to use for the call
ndash The MS communicates of the assigned channel
bull Here the call is between two mobiles
bull The communications is monitored for the ongoing call
12 11
Processbull Handoff (or handover)
ndash MS continually scans for control signals of BS
ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold
ndash Upon that event the MSC will initiate a handoff procedure
ndash Handoff procedures can be implemented transparent to the users no interruption
ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS
12 12
Process
bull Handoffsndash Hard communications with old BS is terminated and
a new communications to a new BS is establishedndash Soft
bull Soft mobile station temporarily connected to more than one base station simultaneously
bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously
bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously
bull Provides diversitybull Occurs at boundaries of sectorscells
12 13
Other Functions
bull Call blockingndash if all traffic channels busy
bull Call terminationndash when user hangs up
bull Call dropndash when BS cannot maintain required signal
strength
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 9
Process
bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to
determine location of subscriber
ndash MSC has current visiting MSC stored in the HLR
ndash Home MSC communicates with the visiting MSC to rout the call
ndash The MSC sends a paging message to the paging message to BS
ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel
12 10
Process
bull Call acceptedndash MS sees the paging
signal and responds to the BS
ndash The BS send response to the MSC
ndash The MSC sets up the call to the BS
ndash The MSC also assigns a air interface channel for the BS to use for the call
ndash The MS communicates of the assigned channel
bull Here the call is between two mobiles
bull The communications is monitored for the ongoing call
12 11
Processbull Handoff (or handover)
ndash MS continually scans for control signals of BS
ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold
ndash Upon that event the MSC will initiate a handoff procedure
ndash Handoff procedures can be implemented transparent to the users no interruption
ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS
12 12
Process
bull Handoffsndash Hard communications with old BS is terminated and
a new communications to a new BS is establishedndash Soft
bull Soft mobile station temporarily connected to more than one base station simultaneously
bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously
bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously
bull Provides diversitybull Occurs at boundaries of sectorscells
12 13
Other Functions
bull Call blockingndash if all traffic channels busy
bull Call terminationndash when user hangs up
bull Call dropndash when BS cannot maintain required signal
strength
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 10
Process
bull Call acceptedndash MS sees the paging
signal and responds to the BS
ndash The BS send response to the MSC
ndash The MSC sets up the call to the BS
ndash The MSC also assigns a air interface channel for the BS to use for the call
ndash The MS communicates of the assigned channel
bull Here the call is between two mobiles
bull The communications is monitored for the ongoing call
12 11
Processbull Handoff (or handover)
ndash MS continually scans for control signals of BS
ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold
ndash Upon that event the MSC will initiate a handoff procedure
ndash Handoff procedures can be implemented transparent to the users no interruption
ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS
12 12
Process
bull Handoffsndash Hard communications with old BS is terminated and
a new communications to a new BS is establishedndash Soft
bull Soft mobile station temporarily connected to more than one base station simultaneously
bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously
bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously
bull Provides diversitybull Occurs at boundaries of sectorscells
12 13
Other Functions
bull Call blockingndash if all traffic channels busy
bull Call terminationndash when user hangs up
bull Call dropndash when BS cannot maintain required signal
strength
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 11
Processbull Handoff (or handover)
ndash MS continually scans for control signals of BS
ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold
ndash Upon that event the MSC will initiate a handoff procedure
ndash Handoff procedures can be implemented transparent to the users no interruption
ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS
12 12
Process
bull Handoffsndash Hard communications with old BS is terminated and
a new communications to a new BS is establishedndash Soft
bull Soft mobile station temporarily connected to more than one base station simultaneously
bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously
bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously
bull Provides diversitybull Occurs at boundaries of sectorscells
12 13
Other Functions
bull Call blockingndash if all traffic channels busy
bull Call terminationndash when user hangs up
bull Call dropndash when BS cannot maintain required signal
strength
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 12
Process
bull Handoffsndash Hard communications with old BS is terminated and
a new communications to a new BS is establishedndash Soft
bull Soft mobile station temporarily connected to more than one base station simultaneously
bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously
bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously
bull Provides diversitybull Occurs at boundaries of sectorscells
12 13
Other Functions
bull Call blockingndash if all traffic channels busy
bull Call terminationndash when user hangs up
bull Call dropndash when BS cannot maintain required signal
strength
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 13
Other Functions
bull Call blockingndash if all traffic channels busy
bull Call terminationndash when user hangs up
bull Call dropndash when BS cannot maintain required signal
strength
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 14
Other Functions Power control CDMA
bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level
bull decrease interference from other usersbull increase capacity of the system
bull Uplinkndash Power control in uplink must make signal powers
from different users nearly equal in order to maximize the total capacity in the cell
bull Downlinkndash In downlink the power control must keep the signal
at minimal required level in order to decrease the interference to users in other cells
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 15
Other Functions Power control CDMA
bull Typesndash Open loop
bull set initial power for MSbull Each MS sets power based on individual
measurementsbull Coarse scale
ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve
system goalsbull Fast power control can mitigate fast fadingbull Three steps
ndash Transmissionndash Measurementndash Feedback
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 16
3G
bull 1G Analog Cellular Phones Needs a modem 96 kbps max
bull 2G Digital Cellular Phones No modem required 193 kbps max
bull 25G General Packet Radio Service (GPRS) 144kbps Data only
bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile
Telecommunications Systemndash CDMA2000
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 17
Organizations
ndash 3GPP 3rd Generation Partnership Project
ndash 3GPP is responsible for writing and maintaining the UMTS specifications
ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 18
3G- Advantages
3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail
short message service (SMS) and Internet access at broadband speeds
bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile
anywhere in the world
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 19
3G Capabilitiesbull Voice quality comparable to the public
switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving
slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission
ratesbull Support for both packet switched and circuit
switched data services like Internet Protocol (IP) traffic and real time video
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 20
Technologies
bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard
used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems
bull 3G Technologies-
ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread
ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier
ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code
ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 21
Evolution Paths
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
25G2G 3G
cdmaOneIS-95A
TDMA
cdmaOneIS-95B Cdma2000 1X
Cdma20001xEV-DV
Cdma20001xEV-DO
GSMGPRS
EDGE WCDMA
GSM Map Core Network
IS-41 Core Network
Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 22
WCDMA
bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz
bull WCDMA is connected to the FDD Phy and the associated protocols Focus here
bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network
bull UMTS refers to the whole network
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 23
UMTS-FDD WCDMA
bull Wideband Direct Sequence Code Division Multiple Access
bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum
bull Individual conversations are encoded with a pseudo-random digital sequence
bull See httpwwwumtsworldcomtechnologyoverviewhtm
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 24
WCDMA Parameters
Channel BW 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 384 Mcps
Frame Length 10 ms (38400 chips)
No of slotsframe 15
No of chipsslot 2560chips (Max 2560 bits)
Power Control Open and fast close loop (16 KHz)
Uplink Spreading Factor 4 to 256
Downlink Spreading Factor 4 to 512
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 25
Spreading Operation
bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two
operationsndash Channelisation (increases signal bandwidth) using
orthogonal codesndash Scrambling (does not affect the signal bandwidth) using
pseudo noise codes
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 26
Codes
Channellization Code Scrambling Code
Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell
UL Separation of terminalsDL Separation ofcellssectors
Length UL4-256 chipsDL4-512 chips
38400 chips
No of codes No of codes under one scrambling code= SF
UL Several millionDL 512
Code Family Orthogonal Variable Spreading Factor
Long 10ms code Gold codeShort code Extended S(2) code Family
Increase BW YES NO
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 27
UMTS Architecture
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
Cell site
Access Network
Core Network
User Equipment
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 28
UMTS Architecture
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 29
UMTS Architecture
bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone
bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem
bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 30
UMTS Architecture
bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation
ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC
ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS
ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management
bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 31
UMTS Protocol Architecture - User Plane
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 32
UMTS Protocol Stack
bull Radio Resource Control-RRC
bull Broadcastmulitcast control- BMC
bull Packet Data convergence Protocol- PDCPndash Header
compression
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 33
Packet SAR
Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 34
Physical Layerbull The physical layer offers information transfer services to
the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels
bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and
receiving signals over the wireless mediandash Measurements
bull SIRbull Tx power Frame error rate etc
bull Physical channel is assigned a specific code
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 35
Transport amp Physical Channels
Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH
Dedicated Physical Control Channel DPCCH
(UL) Random Access Channel RACH Physical random access channel PRACH
(UL) Common packet channel CPCH Physical common packet channel PCPCH
(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH
(DL) Forward access channel FACH(DL) Paging channel PCH
Secondary common control physical channel S-CCPCH
(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH
Signaling physical channels
Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 36
UMTS FDD frame structure
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 37
MAC Layer
bull The MAC layer offers Data transfer to RLC and higher layers
bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically
bit rate within a predefined set per information unit delivered to the physical layer
ndash Service multiplexing on RACH FACH and dedicated channels
ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling
ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 38
Physical Layer
From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 39
RRC Layerbull The RRC layer offers the core network the following
servicesndash General control service which is used as an information
broadcast servicendash Notification service which is used for paging and
notification of a selected UEsndash Dedicated control service which is used for
establishmentrelease of a connection and transfer of messages using the connection
bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover
admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 40
RLC Layer
bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is
appended to the information unit received from the higher layer
ndash Assured and un assured data transferbull The RLC layer comprises the following functions
ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the
WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the
control plane)ndash Duplicate detectionndash Flow controlndash Ciphering
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 41
RLC Layer-Modesbull Transparent-TM
ndash No header attachedndash SARndash SDU discard
bull Delete SDU if not sent before timer expiresndash Used for
bull Voicebull Some signaling
bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability
bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 42
RLC Layer
From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the
UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 43
UE-Call states
bull Designed to ndash Take advantage of bursty nature of
datandash Save batter powerndash Maintains logical session and tracks
mobility but when appropriatendash releases dedicated resources to
increase overall capacityndash asleeps the UE
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 44
UE-Call states
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 45
UE-Call states
bull Idle modendash No active sessionndash UE monitors
Paging CHndash Sleeps between
paging cycles
From httpwwwumtsworldcomtechnologyRCC_stateshtm
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 46
UE-Call states
bull CELL_DCH state (Dedicated)ndash A dedicated physical
channel is allocated to the UE in uplink and downlink
ndash The UE is known on cell level according to its current active set
ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE
ndash Call typesbull Circuit Switched always in
this statebull Packet Switched in this
state if transferring large volume of data
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 47
UE-Call states
bull CELL_FACH state(Forward Access Ch)
ndash No dedicated physical channel is allocated to the UE
ndash The UE continuously monitors a FACH in the downlink
ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel
ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update
ndash Radio not put to sleepndash For packet switched sessions
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 48
UE-Call states
bull CELL_PCH state (Paging Ch)ndash No dedicated physical
channel is allocated to the UE
ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash Sleep between pagesndash A logical session is still upndash The position of the UE is
known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 49
UE-Call states
bull URA_PCH State ndash No dedicated channel is
allocated to the UEndash The UE selects a PCH with
the algorithm and uses DRX for monitoring the selected PCH via an associated PICH
ndash No uplink activity is possible
ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state
ndash Similar to CELL_PCH state only the at the URA level
Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 50
Power Control-PC
bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to
ensure that there is enough power for mobiles at the cell edge
bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control
commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command
ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 51
Power Control
bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss
by means of a downlink beacon signalndash Provide a coarse initial power setting of
the mobile at the beginning of a connection
ndash Apply only prior to initiating the transmission on RACH or CPCH
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 52
Packet Access in WCDMA
bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection
bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared
bull RNC can decide when and how to send packets based on type of packet traffic
ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech
ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video
ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing
ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail
bull RNC can assign a packet to a specific channel
Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 53
Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the
downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft
handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts
bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts
bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink
orthogonal code is reserved according to maximum bit rate
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 54
Packet Access in WCDMA
bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner
bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer
bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate
bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and
bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 55
Packet Access in WCDMA
bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased
bull Advantagesndash resources are in full usage due to longer transmission
timendash small variation in interference levelndash longer uplink range due to lower bit rate
bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 56
Packet Access in WCDMA
bull Time division is normally used with shared channels and code division is normally used with dedicated channels
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 57
Packet Access in WCDMA
bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users
could be based on required transmission powerbull Users close to the BS requires less
transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate
bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput
bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation
From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 58
HSDPA amp Enhance Uplink
bull HSDPA = High Speed Downlink Packet Access
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 59
HSDPA amp Enhance Uplink
bull Remember it is better (more efficient) to have a large number of users sharing a single server
bull This lead to a desire to have fast allocation of shared resources
bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code
bull Uplink resourcesndash Interference at the BS
bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)
bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 60
HSDPA amp Enhance Uplink
bull UTRAN Architecture with HSDPA and enhanced uplink
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 61
HSDPA amp Enhance Uplink
bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK
modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and
coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function
moved to Node-B (WCDMA packet scheduling was done in the RNC)
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 62
HSDPA amp Enhance Uplink
bull Gain in Performance
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 63
HSDPA
bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to
individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes
bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 64
HSDPA
bull New frame structurendash Five subframesW-CDMA
framendash User data can be
assigned on a subframe basis
ndash System can adjust in 2ms
ndash Each subframe is a transmission time interval (TTI) = 2ms
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 65
HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared
resource is also in the time domain
From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 66
HSDPA
bull Another view
From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA
Spreading Code
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 67
HSDPAbull Link Adaptation
ndash Remember the fast power control is commonly used to
bull Maintain constant EnergyNoise ratiobull Reduce effect of fading
ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant
EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation
From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 68
HSDPA
ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)
ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum
bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user
bull 1 ndash 2 Mbs closer to achievable under real conditions
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 69
HSDPA
bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE
bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms
bull CQI (0-30) each mapping into a modulation SF etc
bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression
bull
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 70
HSDPA
bull Schedulingndash The scheduler decides which user
should get access to each TTI ndash CQI provides input into a Scheduler
bull Proportional Fair (PF) Scheduler can be uses
bull Implementation Specific
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 71
HSDPA
bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number
of spreading codes limits rate not power so likely receive first transmission
ndash At greater distances move from BS see more errors IR will require additional transmission but not many
ndash HARQ only retransmit upon an ACK or NACK
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 72
HSDPA
From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 73
HSDPA
bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2
ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent
Scheduling
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 74
Enhance Uplink (HSUPA)
bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far
problem so no higher order modulation can not trade off data rate for EN
bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B
bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 75
Enhance Uplink (HSUPA)
bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at
bull Goal of the scheduler is to assign resource to those UEs with data to send
bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of
the maximum amount of UL resources the UE may use
ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value
bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 76
Enhance Uplink (HSUPA)
bull BS (Node B) sends scheduling grantsndash BS knows
bull Instantaneous interference levelbull All requests
ndash Then determines which grants to sent
bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control
bull HARQ is also used on the uplink
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 77
References 12bull Attar R et al Evolution of cdma2000 cellular networks
multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53
bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49
bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45
bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61
bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36
bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64
bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172
bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007
12 78
References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw
Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and
Techniques CRC Press 2002bull Geert Heijenk
wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf
bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006
bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong
wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink
Packet Access Bringing Increased Throughput and Efficiency to W-CDMA
bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf
bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007