WiMAXWiMAXWiMAXWiMAX

Wh tWh t i i WiMAXWiMAX??WhatWhat is is WiMAXWiMAX??

ABroadbandWirelessAccessNetworkImplementaton

BasedontheIEEE802.16standard Fixedandmobilesolutions Operateswithbothlicencedandunlicencedfrequencies

Intendedforvariousimplementations:asabackhaulsolution,PTPconnections,PTMconnections,localloop

I d iI d i WIMAXWIMAXIntroductionIntroduction toWIMAXtoWIMAX

The802.16ReferenceModel

MAClayer ServicespecificconvergencesublayerSe v ce spec c co ve ge ce sub ayeMACCommonpartsublayer Security(privacy)sublayer

Physicallayer

WiMAXWiMAX b fi (1)b fi (1)WiMAXWiMAX benefits(1)benefits(1) Good capacity GoodcapacityThetotaltheoreticaldatarateofWiMAX isaround

75Mbpsperchannelp p

Widerange andscalability (compared toWiFi) a range of about: arange ofabout:

50kminaLOScommunication 67kminaNLOScommunication

scalability due to: theeasily adaptivenature

f ll f fastinstallationofequipment

WiMAXWiMAX b fib fi (2)(2)WiMAXWiMAX benefitsbenefits (2)(2)

Powermanagementg Lowcost Easeofinstallation Security QoS QoS AvarietyofsupportedservicesandapplicationsVoIP, live streaming audio and video, VoD etc.VoIP,livestreamingaudioandvideo,VoDetc.

802 16 MAC802 16 MAC ll802.16MAC802.16MAClayerlayer

The802.16MAClayertransmissionschemeisyconnectionoriented

Oneormorepairsofmanagementconnectionsforp gmanagementPDUs

OneormoretransportconnectionsfordataPDUs

MAC MAC PDUPDUMAC MAC PDUsPDUs Header +(optional)variablelength payload +optional CRC( p ) g p y p

Generic MAC P l d CRC

Two types of headers :

header PayloadCRC

(optional)

Two types ofheaders :TheGeneric MACheader,theBandwidth request header

The payload may contain 5 different subheaders: Thepayload may contain 5differentsubheaders: Thegrantmanagementsubheader,thefragmentationsubheader,thepacking subheader,themeshbh d h ARQ bh dsubheader,theARQsubheader

F t tiF t ti d d kikiFragmentationFragmentation and and packingpacking

Fragmentation AsingleMSDU

intomultipleMPDUs

Packing Packing MultipleMSDUs

in1MPDU

Q SQ SQoSQoSServiceClasses:ServiceClasses:

Unsolicited grant service (UGS) Unsolicitedgrantservice(UGS) Realtimepollingservice(rtPS)E d d l i i bl i (ERT VR) Extendedrealtimevariablerateservice(ERTVR)

Nonrealtimepollingservice(nrtPS) Besteffortservice(BE)

802 16802 16 Ph i lPh i l ll ll802.16802.16PhysicalPhysical layerlayer layerlayer

1066GHz forLOScommunication 211GHz forNLOScommunicationWirelessMANSCaWirelessMANOFDM Usesa256carrierOFDMsignalWirelessMANOFDMA Usesa2048carrierOFDMsignal

S b l iS b l iSymbol mappingSymbol mapping

QPSKQPSK,16 QAM, and64 QAM

OFDM (1)OFDM (1)OFDM (1)OFDM (1)

Reduces multipath propagation Mapping of symbols to subcarriers Mapping ofsymbolstosubcarriers 256subcarriersS b i Subcarrier types: DataSubcarriers forcarryingdatasymbols

l b f h l PilotSubcarriers forchannelestimation NullSubcarriers forguardbands

OFDM (2)OFDM (2)OFDM (2)OFDM (2)

OFDMusesFastFourierTransform(FFT)tocreateanumberoforthogonalsubcarriers

T=L*Ts

T durationofanOFDMsymbolL numberofdatasymbolsTs symboltime

OFDMA OFDMA OFDMA OFDMA

Used only inmobileWiMAX (IEEE802.16e) Employs 2048 subcarriers Employs2048subcarriers Scalable OFDMA:1282048subcarriers The number of subcarriers may be changed depending Thenumberofsubcarriers maybechangeddependingonbandwidthavailabilityofthechannel

MIMO i MIMO i WiMAXWiMAXMIMO in MIMO in WiMAXWiMAX

Smartantenna technology Multipleantennasatthetransmitterandthepreceiver

Two MIMOmodes:MatrixA a singlestreamMatrixB twostreams

Adaptive modulation and Adaptive modulation and Adaptive modulation and Adaptive modulation and CodingCoding

Themodulationmethodcanbeadaptedtothecurrentchannelconditions

Highdatarateswhenthechannelisgood Use large constellations:64QAM

Lowerrateswhenthechannelispoor Use smallconstellations:QPSKQ

C l iC l iConclusionConclusion

WiMAX isagood solutionforruralareas ease ofinstalation (compared toDSLandCable?)( p ) good covering range andspeed(compared toWiFi?)

Agood way toboost uptheeconomy inunderdevelopedgcountries

Agrowing need formobileWiMAX