Introduction to WirelessIntroduction to Wireless

CS 477CS 477

TechnologiesTechnologies

Tech.Tech. Primary Primary Appl.Appl.

Data RatesData Rates QoS GoalsQoS Goals

WLAN: WLAN: 802.11802.11

Wireless Wireless EthernetEthernet

Hot spot 11, Hot spot 11, 54 Mbps54 Mbps

Best Effort Best Effort ++

WLL:WLL:

LMDS/ LMDS/ MMDSMMDS

Wireless Wireless Cable: Cable: BusinessBusiness

50, 100, 50, 100, 150 Mbps150 Mbps

ATM classesATM classes

WPAN:WPAN:

BluetoothBluetoothTetherless Tetherless ComputingComputing

Master-Master-controlledcontrolled

CellularCellular Mobile Mobile Comm.Comm.

8, 144 kb/s 8, 144 kb/s - 2Mb/s- 2Mb/s

RT & Best RT & Best EffortEffort

Transmission TechniquesTransmission Techniques

Distributed/HierarchicalDistributed/Hierarchical

FDMA/TDMA/CDMAFDMA/TDMA/CDMA

TDD/FDDTDD/FDD

Network TypesNetwork Types

Distributed Network: Distributed Network: Users interface with Users interface with each othereach other• Ad Hoc Network: Self-Ad Hoc Network: Self-

creatingcreating

Hierarchical network: Hierarchical network: Users interface with Users interface with Base Station or Access Base Station or Access PointPoint• Polled: Master-SlavePolled: Master-Slave

MT MT

MT

BS

MT MT

MT MT

Hierarchical NetworksHierarchical Networks

Terminal Equipment

Base Station

DownlinkUplink

Time Division Duplex (TDD)Time Division Duplex (TDD)

Base Station & Terminal Equipment Base Station & Terminal Equipment alternate transmissionsalternate transmissions

Good when amount of downlink data Good when amount of downlink data > amount of uplink data> amount of uplink data

Frequency Division Multiple AccessFrequency Division Multiple AccessFrequency Division Duplex (FDD)Frequency Division Duplex (FDD)

Example: First Generation Cellular

Time Division Multiple AccessTime Division Multiple Access

TDMA - FDD

Time Division Multiple AccessTime Division Multiple Access

Channels allocated by Frequency & Channels allocated by Frequency & TimeslotTimeslot

A Multiframe defines who & what A Multiframe defines who & what transmits during a timeslot (E.g.:)transmits during a timeslot (E.g.:)• Broadcast / Paging / Synchronization Broadcast / Paging / Synchronization

ChannelChannel• Random Access ChannelRandom Access Channel• Signaling ChannelsSignaling Channels• Traffic ChannelTraffic Channel

Frequency Hopped Spread Frequency Hopped Spread Spectrum (FHSS)Spectrum (FHSS)

EDGE TechnologyEDGE Technology

EDGE TechnologyEDGE Technology

Finds Optimal Bit RateFinds Optimal Bit Rate• Selects modulation & coding scheme Selects modulation & coding scheme

based on environmentbased on environment • Uses Link Quality ControlUses Link Quality Control

Varies Modulation SchemeVaries Modulation Scheme• GMSK, 8-PSKGMSK, 8-PSK

Code Rate varies form .37 to 1.0Code Rate varies form .37 to 1.0

EDGE Modulation & CodingEDGE Modulation & Coding

MCS-9MCS-9 8PSK8PSK 11 59.2 kbps59.2 kbps

MCS-8MCS-8 8PSK8PSK 0.920.92 54.4 kbps54.4 kbps

MCS-7MCS-7 8PSK8PSK 0.760.76 44.8 kbps44.8 kbps

MCS-6MCS-6 8PSK8PSK 0.490.49 29.6 kbps29.6 kbps

MCS-5MCS-5 8PSK8PSK 0.370.37 22.4 kbps22.4 kbps

MCS-4MCS-4 GMSKGMSK 11 17.6 kbps17.6 kbps

MCS-3MCS-3 GMSKGMSK 0.850.85 14.8 kbps14.8 kbps

MCS-2MCS-2 GMSKGMSK 0.660.66 11.2 kbps11.2 kbps

MCS-1MCS-1 GMSKGMSK 0.530.53 8.8 kbps8.8 kbps

Direct Sequence Spread Spectrum Direct Sequence Spread Spectrum (DSSS)(DSSS)

1

1

1

1

1

1

1

1

0

00

0

0

0

00

Code Division Multiple Access Code Division Multiple Access (CDMA)(CDMA)

Each bit is transmitted multiple times Each bit is transmitted multiple times at different frequencies, called ...at different frequencies, called ...• Direct Sequence Spread SpectrumDirect Sequence Spread Spectrum• Fast Frequency HoppingFast Frequency Hopping

Message x spreading signalMessage x spreading signal• Pseudo-noise code sequence @ chip ratePseudo-noise code sequence @ chip rate• Codewords are orthogonal to each otherCodewords are orthogonal to each other

Interference LimitedInterference Limited

Multi-Carrier vs. Direct SequenceMulti-Carrier vs. Direct Sequence

Direct Sequence

Multi-Carrier

CDMA 2000 Technology

CDMA EnhancementsCDMA Enhancements

CDMA2000:CDMA2000: Chip rates of N=1, 3, 6, 9, 12Chip rates of N=1, 3, 6, 9, 12 Reduced spreadingReduced spreading Turbo codes: 10Turbo codes: 10-6 -6 vs 10vs 10-3-3

QPSK on Forward (v) Link QPSK on Forward (v) Link • BPSK on Reverse (^)BPSK on Reverse (^)

Spatial Diversity Multiple Spatial Diversity Multiple AccessAccess

SDMA or Smart AntennasSDMA or Smart Antennas• Forms a focused beamForms a focused beam• Allows channels to be reused within a cellAllows channels to be reused within a cell

Multibeam TypeMultibeam Type• Multiple fixed beams with a narrow focusMultiple fixed beams with a narrow focus

Adaptive Array Adaptive Array • Uses Spatial & Angle DiversityUses Spatial & Angle Diversity• Separates signal from its pathSeparates signal from its path

SDMASDMA

Varied Cell SizesVaried Cell Sizes

megacell macrocell microcell picocell

0 100 m 2 km 70 km 200-1000km

Diameter

Frequency AllocationsFrequency Allocations

Licensed: Cellular, Satellite, Licensed: Cellular, Satellite, WLLWLL

Unlicensed: WLAN, WPANUnlicensed: WLAN, WPAN

Licensed, Cellular FrequenciesLicensed, Cellular Frequencies

.824 - .894 US-DC, IS-95.890 - .960 ETACS / NMT / GSM

1.85-1.99 US-DC, IS-95

1.71-1.88 DCS 1800

1.92-2.17 UMTS - W-CDMA

Wireless CableWireless Cable

MMDS

LMDS

Frequency 2.1 & 2.5-2.686 GHz 27.5-28.35 GHz 31-31.3 GHz

Cell Size 25-35 miles 1-3 km

Wireless LAN / PANWireless LAN / PAN

IEEE 802.11BIEEE 802.11B

BLUETOOTHBLUETOOTH

Wireless LANWireless LAN

Unlicensed FrequenciesUnlicensed Frequencies Low Maximum Transmit PowerLow Maximum Transmit Power Possible Contention ProblemsPossible Contention Problems Frequencies Used:Frequencies Used:

• Industrial, Scientific, Manuf. (ISM): 2.4 GHzIndustrial, Scientific, Manuf. (ISM): 2.4 GHz• Unlicenced Nat. Info. Infrastructure (UNII): Unlicenced Nat. Info. Infrastructure (UNII):

5.2 GHz 300 MHz5.2 GHz 300 MHz 5.725 - 5.825 GHz5.725 - 5.825 GHz

IEEE 802.11BIEEE 802.11B

Header

192 us1 Mbps

Data: 1 of 4 rates Uses multiple subcarriers

Training Data

IEEE 802.11IEEE 802.11

Simultaneous Transmissions Possible HiddenTerminal

CSMA/CACSMA/CA

MT A MT B

RTS

MT C

CTS

ACK

Data

IEEE 802.11 ProtocolIEEE 802.11 Protocol

SIFS

PIFS

DIFS

IEEE 802.11 ProtocolIEEE 802.11 Protocol

Possible Simultaneous TXPossible Simultaneous TX CSMA/CACSMA/CA RTS/CTS notifies all in area of TXRTS/CTS notifies all in area of TX SIFS: Short delay before ack.SIFS: Short delay before ack. PIFS: Poll time-sensitive dataPIFS: Poll time-sensitive data

• Point Coordinator polls for high priorityPoint Coordinator polls for high priority DIFS: Anyone may contend to TXDIFS: Anyone may contend to TX

Bluetooth Personal Area Bluetooth Personal Area NetworkNetwork

Radio-based cable replacementRadio-based cable replacement• Low-cost, low-powerLow-cost, low-power• Created by IBM, Intel, Ericsson, Nokia, Created by IBM, Intel, Ericsson, Nokia,

Toshiba in Feb. ‘98Toshiba in Feb. ‘98• Joined by Motorola, Lucent, Microsoft, 3COMJoined by Motorola, Lucent, Microsoft, 3COM

FeaturesFeatures• Piconet: Swaps data at up to 10 metersPiconet: Swaps data at up to 10 meters• Data Rate: 721 kbps to 1 Mbps, or 3 Voice Data Rate: 721 kbps to 1 Mbps, or 3 Voice

@ 64 kbps@ 64 kbps

Bluetooth ApplicationsBluetooth Applications

Cordless desktop with peripheralsCordless desktop with peripherals Cordless phoneCordless phone LAN Access - Internet bridgeLAN Access - Internet bridge File Transfer: PDA synchronization File Transfer: PDA synchronization

with PCwith PC Headset / Intercom / Dial up networkHeadset / Intercom / Dial up network Home entertainment, lighting, Home entertainment, lighting,

securitysecurity

Bluetooth ProtocolBluetooth Protocol

IEEE 802.15 Standard defines layers IEEE 802.15 Standard defines layers 1 & 21 & 2

ISM Band: 2.4 GHz ISM Band: 2.4 GHz Spread spectrum: FHSSSpread spectrum: FHSS 1 Master polls up to 7 Slaves1 Master polls up to 7 Slaves Auto-initiation of updatesAuto-initiation of updates

Cellular SystemsCellular Systems

Functions of 2G NetworkFunctions of 2G Network

Cell SearchCell Search Location UpdateLocation Update Speech CallsSpeech Calls

• Mobile Originated CallMobile Originated Call• Paging: Mobile Terminated CallPaging: Mobile Terminated Call

HandoverHandover• Hard HandoverHard Handover• Soft HandoverSoft Handover

Short Message ServiceShort Message Service

Features of 3G CellularFeatures of 3G Cellular

Bit rates to 2 MbpsBit rates to 2 Mbps Variable Bit RateVariable Bit Rate Multiple services multiplexed on single Multiple services multiplexed on single

connection: voice, video, packet dataconnection: voice, video, packet data Real time and Best Effort trafficReal time and Best Effort traffic FER: 10% to 10FER: 10% to 10-6-6

Handovers between 2G & 3G systemsHandovers between 2G & 3G systems Asymmetric uplink and downlinkAsymmetric uplink and downlink

ServicesServicesClass of Class of ServiceService

CharacteristicsCharacteristics ApplicationsApplications

ConversationalConversational Delay-Delay-sensitive, sensitive, SymmetricSymmetric

Voice, Voice, videotelephonyvideotelephony

StreamingStreaming Constant delay, Constant delay, AsymmetricAsymmetric

Multimedia, Multimedia, web broadcastweb broadcast

InteractiveInteractive Request/ Request/ ResponseResponse

Web browsing, Web browsing, network gamesnetwork games

BackgroundBackground Delay-Delay-insensitiveinsensitive

EmailEmail

Network ArchitectureNetwork Architecture

Universal Mobile Universal Mobile Telecommunications System Telecommunications System

(UMTS)(UMTS)

VocabularyVocabulary

Control Plane:Control Plane: Radio Resource Radio Resource

ControlControl Mobility MgmtMobility Mgmt Call ControlCall Control

User Plane:User Plane: SpeechSpeech Circuit-Switched Circuit-Switched

DataData Packet-Switched Packet-Switched

DataData

High Level System ArchitectureHigh Level System Architecture

UserEquipment

(UE)

UMTSTerrestrial

RadioAccess

Network(UTRAN)

CoreNetwork

(CN)

Uu Iu

User EquipmentUser Equipment

UMTSTerrestrial

RadioAccess

Network(UTRAN)

CoreNetwork

(CN)

Uu Iu

MobileEquip.

USIMSubscriber

IdentityModule

Radio Interface ProtocolsRadio Interface Protocols

Physical Layer

Medium Access Control

Radio Link Control

Control Plane Protocols User Plane Protocols

Logical Channels

Transport Channels

Logical ChannelsLogical Channels

Control Channels:Control Channels: Broadcast Control (BCCH): Downlink Broadcast Control (BCCH): Downlink

broadcasts system information broadcasts system information Paging Control (PCCH): Downlink incoming Paging Control (PCCH): Downlink incoming

call info.call info. Dedicated Control (DCCH): Bidirectional Dedicated Control (DCCH): Bidirectional

control info (inside call)control info (inside call) Common Control (CCCH): Bidirectional Common Control (CCCH): Bidirectional

control info (outside call)control info (outside call)

Logical ChannelsLogical Channels

Traffic Channels:Traffic Channels: Dedicated Traffic (DTCH): Dedicated Traffic (DTCH):

Bidirectional point-to-point dedicated Bidirectional point-to-point dedicated channelchannel

Common Traffic (CTCH): Downlink Common Traffic (CTCH): Downlink point-to-multipoint channelpoint-to-multipoint channel

Radio Link ControlRadio Link Control

Layer 2:Layer 2: Transparent: No protocolTransparent: No protocol Unacknowledged ModeUnacknowledged Mode Acknowledged ModeAcknowledged Mode

UTRANUTRAN

CoreNetwork

(CN)

Uu Iu

MobileEquip.

USIMSubscriber

IdentityModule

Node B

RNCNode B

Node B

Node B

RNC

UTRAN ProtocolsUTRAN Protocols

Uses ATM base:Uses ATM base: ATM AAL5: ControlATM AAL5: Control ATM AAL2: SpeechATM AAL2: Speech RANAP: Radio Access Network RANAP: Radio Access Network

Application ProtocolApplication Protocol

Core NetworkCore Network

Uu Iu

MobileEquip.

USIMSubscriber

IdentityModule

Node B

RNCNode B

Node B

Node B

RNC

MSC/VLR

GMSC

SGSN GGSN

HLR

PSTN

Internet

Core Network NodesCore Network Nodes Circuit-Switched: Circuit-Switched:

• Mobile Switching Center (MSC): switches PCM Mobile Switching Center (MSC): switches PCM speechspeech

Packet-Switched:Packet-Switched:• Serving GPRS Support Node (SGSN) Serving GPRS Support Node (SGSN) • Gateway Support Node (GGSN): Interface to Gateway Support Node (GGSN): Interface to

global Internetglobal Internet CommonCommon

• Home Location Register (HLR): Permanent Home Location Register (HLR): Permanent source of subscription informationsource of subscription information

• Visitor Location Register (VLR): Local source for Visitor Location Register (VLR): Local source for user subscription optionsuser subscription options

GPRS Network ArchitectureGPRS Network ArchitectureServing GPRS Support Node (SGSN)Serving GPRS Support Node (SGSN)

• Interfaces with MS via BSInterfaces with MS via BS• Performs security, mobility / VLR functionsPerforms security, mobility / VLR functions

Gateway GPRS Support Node (GGSN)Gateway GPRS Support Node (GGSN)• Interfaces to InternetInterfaces to Internet• Learns MS location via HLRLearns MS location via HLR• Routes data to the SGSN using IPRoutes data to the SGSN using IP

Network is evolving as 3G/4G progressesNetwork is evolving as 3G/4G progresses

Physical Layer ChannelsPhysical Layer Channels

Common ChannelCommon Channel

Dedicated ChannelDedicated Channel

Shared ChannelShared Channel

Dedicated Transport ChannelDedicated Transport Channel

Circuit-switched services: speech, Circuit-switched services: speech, teleconferencingteleconferencing

Variable bit rateVariable bit rate• Fast data rate changeFast data rate change

Soft handoverSoft handover Physical channels:Physical channels:

• Dedicated Physical Data Channel: User dataDedicated Physical Data Channel: User data• Dedicated Physical Control Channel: Physical Dedicated Physical Control Channel: Physical

layer controllayer control

Common Transport ChannelsCommon Transport Channels

Broadcast: Downlink cell-specific Broadcast: Downlink cell-specific informationinformation

Forward Access: Downlink control & packet Forward Access: Downlink control & packet info.info.

Paging: Downlink data relevant to pagingPaging: Downlink data relevant to paging Random Access: Uplink request for serviceRandom Access: Uplink request for service Uplink Common Packet: Extended data Uplink Common Packet: Extended data

requestsrequests Downlink Shared: Shared for dedicated Downlink Shared: Shared for dedicated

data/controldata/control