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LTE, WiMAX and 4G
Mobile Communication and Mobile Computing
Prof. Dr. Alexander Schill
http://www.rn.inf.tu-dresden.de
Department of Computer Science Institute for System Architecture, Chair for Computer Networks
http://www.rn.inf.tu-dresden.de/http://www.rn.inf.tu-dresden.de/http://www.rn.inf.tu-dresden.de/http://www.rn.inf.tu-dresden.de/8/11/2019 04 LTE and Beyond
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LTE: Characteristics
LTE = Long Term Evolution
European implementation of IMT (International MobileTelecommunications) by ETSI (European TelecommunicationStandards Institute)
Packet oriented propagation only
High data rates Up to 300 Mbit/s Downlink
Up to 75 Mbit/s Uplink
Flexible frequency assignment
About 40 frequency ranges
Varying frequency blocks (1.4, 3, 5, 10 and 20 MHz)
small latency of 5ms between mobile phone and conventionaltelephone network
optimized for travelling speeds of up to 15 km/h (up to500km/h possible)
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LTE Reference Architecture
UE eNodeB S-GW P-GW
MME
LTE - Uu S1-U S5/S8
S1-MME S11
HSSS6a
PCRF
Gx
SGi PSTN
eUTRAN Core Network
NodeB + RNC (3G) merged into evolved NodeB (eNodeB)
Core network Serving Gateway (S-GW)
Mobility Management Entity (MME)
PDN Gateway (P-GW)
Home Subscriber Server (HSS)
Policy Control and Charging Rules Function (PCRF)3
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LTE User Equipment
Examples of LTE-enabled devices
iPhone 5, Samsung Galaxy S3 LTE,Samsung LTE Stick
Five device categories
Category 1 2 3 4 5
Peak data rate
Mbit/s
DL 10 50 100 150 300
UL 5 25 50 50 75
RF bandwidth 20 MHz
Modulation QPSK, 16QAM QPSK, 16QAM,64QAM
2 Rx diversity Assumed in performance requirements
2x2 MIMONot
supported
Mandatory
4x4 MIMO Not supported Mandatory4
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LTE: Frequency bands
Germany (currently)
5 bands: 800 MHz, 900 MHz, 1800 MHz, 2000 MHz, 2600MHz
Rural Areas
800 MHz (Vodafone and Telecom)
Urban Areas
800 MHz (Vodafone)
1800 MHz (Telecom) -> reassignment from GSM
2600 MHz planned for crowded areas in cities (stations,shopping malls, etc.)
O2 and E-Plus cover currently only few areas
USA: 700MHz, 1700MHz and 2100 MHz
Europe: 800 MHz
Bands 700, 800, 1800 and 2600 MHz will potentiallyallow world wide roaming in the future
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LTE: German frequency bands
frequency spectrum of the digital dividend:
better building penetration & propagation features > higher range
frequency spectrum of the IMT extension band:Enough blocks for 20 MHz bandwidth > Higher data rate
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Duplex gap*12 MHz820 MHz 832 MHz
5 MHzfrequencyblock
(72 Mhz)790 MHz 862 MHz
10 x 5 MHzblocks uncoupled2570
MHz2620MHz
5 MHzfrequencyblock
(190 Mhz)2500MHz
2690MHz
* The Duplex gap is meant as a fallback position for wireless production technology.
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LTE: Modulation basics OFDM
LTE Modulation techniques are based on OFDM(Orthogonal frequency-
division multiplexing) in OFDM data is distributed over a large number of closely spaced
orthogonalsubcarriers
(two subcarriers are orthogonal if the maximum amplitude of onesubcarrier is reached while the other subcarriers amplitude is zero)
Subcarriers modulated with conventional modulation scheme (QAM)
Pro: robust against interference because interference on subcarrier doesnot influence the whole frequency band, Improved spectrum efficiencyand lower bandwidth demand W with OFDM
Con: expense for coding and decoding and therefore the powerconsumption increases with the number of subcarriers
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OFDM with 3 subcarriers
f f
FDM with 3 subcarriers
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LTE: Modulation techniques
LTEs modulation techniques used for Downlink and Uplinkare based on OFDM with a special focus on simultaneousaccess of multiple users
*OFDMA(Orthogonal frequency-division multiple access)for Down Link
subsets of subcarriers are assigned to individual users >simultaneous (low data rate) transmission for severalusers
*SC-FDMA(Single Carrier FDMA) for Up Link multiple access realized by insertion of coefficients on the
transmitter side before Fourier transformation, andremoving on the receiver side. Different users areassigned to different coefficients (subcarriers). More
energy-efficient for battery-driven mobile devices. 9
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LTE E-UTRAN Architecture
Flat architecture:
eNodeBs form E-UTRAN NodeB + RNC (3G)
merged into evolvedNodeB (eNodeB)
eNodeB manages one orseveral cells
Responsibilities
IP header compression
Encryption
Radio resource
management Connectivity to core
network
Bearer management
UE mobility
Core Network
E-UTRAN
eNodeB
eNodeB
eNodeB
MME S-GW MME S-GW
comm. between
eNodeBs
signaling to
MMEs bearer path
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LTE Bearer
UE P-GWeNodeB S-GW
UL-TFT
Application/service layer
UL-TFT
DL-TFT
DL-TFT
Radio bearer S1 bearer S5/S8 bearer
RB-ID S1-TEID S1-TEID S5/S8-TEID
Different QoS requirements of applications (VoIP, browsing, filedownload) are mapped to bearers
Bearers cross multiple interfaces, each part is individually mapped tolower layer bearer with own bearer id
Each node manages binding between bearer ids
Packet filters (Traffic Flow Templates (TFT)) assign IP packets to bearers
(e.g. based on IP header information and TCP port numbers) 11
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LTE Interworking
UE E-UTRAN S-GW P-GW
MME
LTE - Uu S1-U S5/S8
S1-MMES11
3G-SGSN
S3 S4
non-3GPP networks
(CDMA2000, WiMAX,)
UTRAN
(GSM, UMTS)
Interworking and mobility with other 3GPP defined networks as
well as non-3GPP defined networks
Service Gateway (S-GW) is mobility anchor for other 3GPPnetworks
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LTE Advanced
Specified as LTE Release 10
Improved performance
Data rate up to 1 GBit/s
End-to-end delay 20 30 ms
Enhancements
Carrier aggregation up to 5 * 20 MHz -> 100MHz
Possible in contiguous and non-contiguous spectrum allocations
Multiple Input, Multiple Output (MIMO)
Up to 4 LTE antennas in LTE devices to use MIMO also for Uplink
Base stations can be equipped with up to 8 antennas
Support for relay node base stations
Connected to base station only
Improve signal quality at cell borders
Support of low power nodes such as picocells and femtocellsfor crowded areas
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WiMAX / IEEE802.16
WiMAX: Worldwide Interoperability for Microwave
Access, standardized by IEEE 802.16 and WiMAX-Forum(more than 230 members, including AOL, DeutscheTelekom, Intel, Microsoft, Nokia)
IEEE 802.16 FBWA (Fixed Broadband Wireless Access) is
an alternative for broadband cable services like DSL;frequency range: initially 10-66 GHz, in assumption ofLOS (line of sight)
Enhancement IEEE 802.16a; frequency band: 2-11 GHz,
NLOS (non line of sight)
Enhancement IEEE 802.16efor MBWA (MobileBroadband Wireless Access); frequency band: 2-6 GHz,NLOS
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WiMAX/IEEE 802.16: overview
Standard 802.16 802.16a 802.16e
Spectrum, GHz 10-66 2-11 2-6
LOS-condition LOS NLOS NLOS
Bit rate, MBit/s 32-134
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WiMAX: Frequencies worldwide
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For Germany especially: 3,41-3,452 GHz and 3,51-3,552 GHz
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802.16 Physical Layer
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Specification Frequency
band
Channel
bandwidth
Duplex
method
Modulatio
n
Line-of-
Sight
WirelessMAN-SC 10-66 GHz
Licensed
bandwidth
20, 25,
28 MHz
TDD, FDD Single
carrier
LOS
WirelessMAN-
SCa
2-11 GHz
Licensed
bandwidth
3,5, 7, 10,
20 MHz
TDD, FDD Single
carrier
NLOS
WirelessMAN-
OFDM
2-11 GHz
Licensed
bandwidth
variable
1,25-20
MHz
TDD, FDD OFDM NLOS
WirelessMAN-
OFDMA
2-11 GHz
Licensedbandwidth
variable
1,25-28MHz
TDD, FDD OFDMA
(multipleaccess)
NLOS
WirelessHUMAN 2-11 GHz
License-
free
10, 20 MHz TDD OFDM,
OFDMA
NLOS
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WiMAX: Modulation
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WiMAX: strong dependency
of effective channelcapacity, spectrumefficiency, range, signal-noise-ratio etc. on usedmodulation method:
BPSK Binary Phase Shift
Keying QPSK Quadrature Phase
Shift Keying
16QAM QuadratureAmplitude Modulation
64QAM Quadrature
Amplitude Modulation
(typical example distribution (percentage)of users in different coverage areas)
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802.16 Medium Access
TDMA (Time Division Multiple Access)
Each communication channel gets fixed slot for datatransmission
DAMA (Demand Assigned Multiple Access)
2 Phases:
Reservation: every station tries to acquire slot foreach transmission phase (collision possible)
Data transmission: within reserved slot guaranteedcollision free transmission
Duplex connection
FDD (Frequency Division Duplex): simultaneous use ofdifferent frequencies
TDD (Time Division Duplex): Switching between up-and downlink on the same frequency
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WiMAX: Cellular backbone
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Network
Point to PointBackbone
Point to Multipoint
WiMAX cell
UMTS cell
802.16
PHY 802.16OFDM-PHYe.g Gigabit
Ethernet
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1) Last Mile or
2) Point to Multipoint (PMP) network (see bellow) Base Station (BS) is the central point for the
Mobile Stations (MS)
Sending in Downlink-direction: Broad-, Multi-, Unicast
Connection of a MS to BS is characterized via Channel ID (CID),
Channel id gives the possibility for the BS to receive multicastmessages
802.16 Network topologies (1&2)
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MS/BS
MS/BS
BS
MS
MSMS MS
Network
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802.16 Network topologies (3)
3) Mesh network
MS can communicate directly
Mesh BS: connected with a network outside the mesh
other differentiation
neighbor: direct connection to a node
neighborhood: all other neighbors
extended neighborhood: remote neighborhoods
23Mesh MS
Mesh BS
Mesh MSMesh MS
Mesh MS
Mesh MSMesh MS
Network
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MBWA (Mobile Broadband Wireless Access);802.20 (1)
Working Group 802.20 originated from 802.16 goal: Specification of PHY and MAC for Packet-based MBWA-
System
Should close the gap between WLAN and slower but highlymobile networks (UMTS)
features variable cell size Handover- and Roaming-mechanism Velocity up to 250 km/h Transport of IP-data traffic
QoS on transport layer
Licensed bands below 3,5 GHz, variable bandwidth NLOS, for in- and outdoor TDD, FDD, Half-Duplex FDD More than 100 simultaneous sessions per cell End to End Security, AES
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Goals
Peak data rates
802.20 (2)
characteristic goal
User data rate Downlink > 1 MBit/s
User data rate Uplink > 300 KBit/s
Data rate Downlink per cell > 4 MBit/s
Data rate Uplink per cell > 800 KBit/sCell size Correspond. to all modern MANs, with ability to
use the existing infrastructure
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Data rates 1.25 MHz 5 MHzDownlink Uplink Downlink Uplink
Peak data rate
per user
4.5 MBit/s 2.25
MBit/s
18 MBit/s 9 MBit/s
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UMTS/HSPA/HSPA+ WiMAX MBWA LTE
Mobility Handover, Roaming ---------------- Handover, Roaming, Mobile IP ---
Max Speed 300 km/h 120 km/h 250 km/h 500 km/h
Switching type circuit and packet ---------------- Packet switching ----------------
Peak datarates Down
Link
2/14,4/28 Mbit/s(5MHz channel)
365 Mbit/s(2x 20MHzchannel,variations)
100 - 300 Mbit/s(1.4-20 MHzchannel)
Cell sizespico(1)-, micro(2)-,macro(3)-cells
variablepico(1)-,micro(2)-,macro(3)-cells
pico(1)-, micro(2)-,macro(3)-cells
QoSEnd-to-end QoSDifferent classes
End-to-endQoSDifferentclasses
End-to-endQoS
End-to-end QoSDifferent classes
Scalability ---------------- variable data rate ~ Multiple users per BS --------------
Air InterfaceCDMAadaptive ModulationMIMO
OFDM(A),adaptiveModulationMIMO
OFDMAdaptiveModulation
OFDM, SC-FDMAadaptiveModulationMIMO
Security AES AES, X.509 AES SNOW 3G
Technology comparison pre-4G
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(1)
1km
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4G requirements
high mobility Handover, Roaming,
velocity up to 300 km/h
switching technique pure packet switching
integrated multi-media-services VoIP, TVoIP, VoD,Streaming
high data rate (1Gbit/s)
even at high mobility shouldbe like DSL
Size of cell variable and scalable
QoS prioritization of specific data packages
scalability available and reliable with many users
air interface OFDM (better spectrum efficiency) security up to date standards (e.g. AES)
Extension / integration of UMTS and WLAN approaches
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Technology comparison 3G to 4G
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LTE (3G) LTE Advanced (4G)
Peak data rateDown Link (DL)
300 Mbit/s 1 Gbit/s
Peak data rateUp Link (UL)
75 Mbit/s 500 Mbit/s
Transmissionbandwidth DL
20 Mhz (max.) 100 Mhz
Transmissionbandwidth UL
20 Mhz (max.) 40 Mhz (requirements asdefined by ITU)
CoverageFull performance up to5km
Same as LTE requirement.Should be optimized ordeployed in local areas/microcell environments.
Scalablebandwidths
1.4, 3, 5, 10 and 20 MHz 20-100 MHz
Scalabilityvariable data rateMultiple users per BS
variable data rateMultiple users per BS
Capacity200 active participantsper cell at 5 MHz
3 times higher than that inLTE
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Summary: Data rates and mobility
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High-speed
/Wide-area
Medium-speed
/Urban area
Walking
/Local area
Standing
/Indoors
2G
Source:www.3g.co.uk
Mobility
0.1 1 10 100 200 1000Bitrate, MBit/s
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Some further readings
Eds.: Sesia, S., Toufik, I., Baker, M.: LTE The UMTS
Long Term Evolution From Theory to Practice, Whiley,2009
LTE:
www.gsmworld.com
www.ltemobile.dewww.apwpt.org
WiMAX technology:
www.wimaxforum.org
IEEE web sites for 802.16 and 802.20:grouper.ieee.org/groups/802/16/ and /802/20
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