A Technical Study of Long Term Evolution (LTE) and LTE-Advanced by Olufemi Amao

8/13/2019 A Technical Study of Long Term Evolution (LTE) and LTE-Advanced by Olufemi Amao

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EEL-6936. Advanced Topics in Wireless Communications

A Technical Study of Long Term Evolut ion (LTE) and LTE-Advanced

By OlufemiAmao


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Contents

Introduction5

1.BriefHistoryofCellularSystems.6

2.BasicTransmissionSchemeinLTE.9

2.1DownlinkTransmission.9

2.1UplinkTransmission.11

3.PhysicalLayerOverviewofLTE 13

3.1DownlinkPhysical Layer.13

3.2UplinkPhysicalLayerOverview..16

4.Physical Channels andSignals..18

4.1DownlinkPhysicalChannels..18

4.2DownlinkPhysicalSignals20

4.3UplinkPhysicalChannels21

4.4UplinkPhysicalSignals21

5.MIMOTechnologiesinLTEandLTEAdvanced22

6.OtherLTEAdvancedTechnologies27

6.1Carrieraggregation27

6.2CoordinatedMultipointTransmission/Reception29

6.3Relaying31

Conclusion..33

Reference...34


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Figures

Figure1.1:Cellularhistory.........................................................................................7

Figure1.2:3Gevolution..............................................................................................8

Figure2.1: OFDMSignalBlockGenerator..................................................................9

Figure2.2: SchedulingconceptinOFDM..................................................................10

Figure2.3:OFDMSignalrepresentedinFrequencyTimedomain.............................11

Figure2.4:TransmitterstructureforSCFDMA.........................................................12

Figure2.5:Differencesbetween SCFDMAandOFDM...........................................12

Figure3.1:FDDFrameStructure.13

Figure3.2:TDDFrame (for5msswitchpointperiodicity)14

Figure3.3: OFDMresourceblockconcept15

Figure3.4:Overviewofdownlinkphysicalchannelprocessing..16

Figure3.5:Overviewofuplinkphysicalchannelprocessing.17

Figure4.1:Transportchannelsmappedtophysicalchannelsinthedownlink.19

Figure4.2:TransportchannelsmappedtophysicalchannelsintheUplink.21

Figure5.1:SimplifiedtransmissionmodelforaMIMOsystemwith3TXandRXantenna22

Figure5.2Closedloopspatialmultiplexingusing NantennaandMlayers.23

Figure5.3:OpenloopspatialmultiplexingwithNantennasandMlayers25

Figure5.4:SFBCwithtwotransmitantennasondownlink..26

Figure5.5:SFBC+FSTDwithfourtransmitantennasondownlink.26

Figure6.1:carrieraggregationtechniques.27

Figure6.2:ExampleofLTEcarrieraggregationscheme..28

Figure6.3:IntraandInterCoMPconcept..29

Figure6.4:demodulationbasedonUEspecificRS.30

Figure6.5:demodulationbasedoncellspecificRS.30


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Figure6.6:Onewayrelaymodel.31

Figure6.7:Twowayrelaymodel 31

Figure6.8:Shared relaymodel 32

Figure6.9:Powercomparisonanalysiswithdifferentrelaytechniques32

Tables

Table2.1Transmissionbandwidthconfiguration..............................................................10

Table5.1:CodebookfortransmissionforTwo antennaports...........................................24

Table5.2CodebookfortransmissionforFourantennaports.............................................24


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Introduction

InApril

2008,

astudy

termed

Requirement

for

Further

Advancement

for

EUTRA

also

called

LongTermEvolutionAdvanced(LTEAdvanced)wasinitiated.LTEAdvancedaimstoenhancethe

systemperformanceandcapabilitiesinexistingLTE.ThemaingoalofLTEAdvancedistoensure

thatalltherequirementofIMTAdvancedasdefinedbytheInternationalTelecommunication

Union(ITU)ismetandevenexceeded.Hence,agoodunderstandingofLTEisrequiredinorderto

understandandappreciatethekeytechnologicalcomponentsthatarebeingconsideredinLTE

Advanced.LTEAdvancedshouldbebackwardcompatiblewithLTE.Anoverviewofthephysical

layerinLTEisreviewedinthisreport;thisiscloselyfollowedwithareviewofsomeofthose

componentsspecifictoLTEAdvanced.


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Chapter1BriefHistoryofCellularsystems

Cellularsystemshaveconstantlyevolvedsincetheywere firstproposed in1947.Their

ubiquitousreachhasdrivenglobalorganizationssuchastheThirdGenerationPartnership

Project(3GPP)tothedevelopmentsofmobiletechnologies.The3GPPisacollaborationof

groupsoftelecommunicationsassociations,setuptomakeagloballyapplicablethirdgeneration

(3G)mobilephonesystemspecification,withinthescopeoftheInternationalMobile

Telecommunications2000(IMT2000)projectoftheInternationalTelecommunicationUnion

(ITU). 3GPPTSGRANisthetechnicalspecificationgroupthathasdevelopedWidebandCode

DivisionMultipleAccess(WCDMA),HighSpeedPacketAccess(HSPA),aswellasLTE.Thegroups

iscurrently intheforefrontoffuturetechnologies.

Thehistoryofthemobilecellularsystemsisoftendividedintogenerationstodistinguishthe

technologicaldevelopmentandimprovementovertheyears.Firstgenerationcellularsystems

(1G)suchasAMPS,werebasedonanalogcommunicationtechnologythatoftenprovidedsome

voiceandverylimitedcircuitswitcheddataservices.FirstgenerationsystemsuseFrequency

DivisionMultipleAccess(FDMA)andoperateinthe450and800MHzfrequencyband.

Secondgenerationcellularsystems(2G),arebasedondigitalcommunicationstechnology.

Comparedtotheirpredecessors,2Gsystemshadimprovedspectralefficiency(increased

numberofuserspercell).Thiswaspossiblebecausedigitalvoicecouldbecompressedand

multiplexedmoreeffectively,thusallowingforfargreatermobilephonepenetration.Basedon

thetypeofmultiplexingused,2GsystemsarecategorizedaseitherTimeDivisionMultiplexing

Access(TDMA) basedsuchasGSMorCodeDivisionMultipleAccess(CDMA)basedsuchasIS95.

TheinitialformofGSMoperatedinthe900,1800and1900MHzfrequencyandusedTDMAas

itsmultiaccessschemeforcircuitbasedtransmissionofdigitizedvoice.Aninitialdatarateofup

to9.6kb/swaspossible.Theprimarydataservicesin2Gweretextmessaging(SMS)andcircuit

switcheddataservicessuchasemail.Theneedtoimprovetheexisting2Gusheredinafew

upgradesthatresultedinsomepacketswitchedfunctionalityandwasknownas2.5Gbased

cellulartechnology.GPRS,EDGEand1XRTTT.

Thirdgenerationtechnologies3G,setthestagefortheinternationalizationofcellular

standards. Priortothis,CDMAbasedsystemsweremainlydeployedinNorthAmericawhile

GSMsystemswerecommoninEurope.Radioaccessdevelopmenton3Gishandledin3GPP,

althoughtheinitialdevelopmentstartedbefore3GPPwasformed.Unlike2Gor2.5G,3Gallows

simultaneoususeofvoiceanddataservicesandoperatedatahigherdatarates.Additional

workon3Ghasbeendrivenbytheneedforacellularsystemthatwouldprovidereducedcost

perbit,Increasedserviceprovisioning,flexibilityofuseonexistingandnewfrequencybands,

simplifiedarchitectureandareasonableterminalpowerconsumption. Therehavebeen

substantialresearchactivitiesdedicatedtowardsimproving3G.The3GPPdocumentsare

dividedintoreleases,whereeachreleasehasasetofadded features,comparedtothe


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previousreleases.3GinEuropewasnamedUniversalMobileTelecommunicationsServices

(UMTS).

WidebandCDMA(WCDMA)wasselectedasthetechnologyforUMTSinthepairedspectrum

(FDD)andTDCDMA(TimeDivisionCDMA)intheunpairedspectrum(TDD).Itoffereda

downlinkspeedofabout384Kbsandanuplinkofabout128Kbps.3GsystemsbasedonTDSCDMAwaslaterdevelopedinChinaandmergedasadditionaloptionforTDDmode.Thefirst

majoradditionofradioaccessfeaturestoWCDMAwasinRelease5(HSDPA)andRelease6

(EnhancedUplink).Together,theyarereferredtoas(HighSpeedPacketAccess)HSPA.HSPA

providesamaxdownlinkspeedofabout 14Mbit/sanduplinkofabout5.7Mbit/s. HSPA+

increasedHSPAsdataratesresultinginadownlinkof56Mbit/sandanuplinkofupto22Mbit/s

inrelease7,usingthesameaccesstechnologyasrelease6butwithimprovedantenna

technologyandhigherordermodulation.

Release8offeredasignificantimprovementinperformanceovertheexisting3Gstandards.A

feasibilitystudyontheLongTermEvolution(LTE)wasproposedin2004aspartofrel8.LTE

representsanefficientpacketbasedradioaccessnetworkthatprovidesfullIPbased

functionalitywithlowlatencyandlowcost.LTEisseenasanevolutionoftheUMTS/3GPP3G

standardswithincreasedspeedsandgeneralimprovedperformance,althoughtherearemajor

stepchangesbetweenLTEandits3GPPpredecessors. Anumberofnewtechnologiesthatmake

uptheLTEsuiteswouldbeintroducedanddiscussedinsubsequentchaptersofthisreport.

Figure

1.1:

Cellular

history


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Fourthgenerationsystems(4G)isexpectedtomeetIMTAdvancedrequirements foran allIP

packetswitchednetworks,mobileultrabroadbandgigabitspeedaccessandmulticarrier

transmission.LTErev8doesnotmeetthestandardsfor4Gsystems,hencetheneedforLTE

Advancedasdescribedinrel9andbeyond.LTEAdvancedmeetstherequirementfor4G.LTE

AdvancediscompatiblewiththefirstreleaseofLTE(LTErel8)equipmentandcansharethe

samefrequencyband.TheITUhascoinedthetermIMTAdvancedtoidentifymobilesystems

whosecapabilitiesgobeyondthoseofIMT2000

Figure2.2:3gevolution


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Chapter2 BasicTransmissionSchemeinLTE

2.1 DownlinkTransmission

LTE downlink transmission scheme is based on Orthogonal Frequency Division Multiplexing

(OFDM).OFDMmakesuseofalargenumberofcloselypackedorthogonalsubcarriersthatare

transmitted inparallel.Eachsubcarrier ismodulated independentlyat lowsymbolrate.When

severalhundredsofthesesubcarriersarecombinedusingan IFFTprocess,theresult isadata

rate similar to conventional singlecarriermodulation in the samebandwidth.As longas the

orthogonalnaturesof the subcarriers aremaintained, subcarriersdonot interferewitheach

other.Carrierspacing in LTE is fixedat15KHz. TheOFDMsignalgeneration isshown in the

figure2.1below.

Source(s) 1:NQAM

Modulator

QAM symbol rate =N/Tusymbols/sec

Nsymbolstreams

1/Tusymbol/sec

IFFT

OFDMsymbols

1/Tusymbols/s

N:1Useful OFDMsymbols

Figure2.1:OFDMSignalBlockGenerator

OFDMprovidesahighdegreeofrobustnessagainstchannelfrequencyselectivityduetoits

relativelongsymboltimeandcyclicprefix.Thecyclicprefixensuresintersymbolinterference

(ISI)doesnotspillintothenextFFTperiod,byensuringthatthedelayspreadiscontainedwithin

thecyclicprefix.LTEdefinestwoformsofCyclicprefix;normalandextended. Cyclicprefix

contributestotheoverall length of the OFDM symbol and are discarded before the FFT

operation at the receiver. Anormalcyclicprefixofabout5sisusedinsmallcellenvironment,

whileextendedcyclicprefixofsize17scanbeusedinenvironmentwithextremetime

dispersionorinthecaseofSingleFrequencynetwork.

InSinglecarrier,equalizationisoftenusedtocorrectsignaldistortionthatoccursdueto

frequencyselectivenatureofthechannel.Theadditionalcomplexityassociatedwithusing

equalizationathighbandwidthabove5MHz,makessinglecarrierunattractiveforLTE. OFDM

providesadditionalbenefitstoLTEsuchastheabilitytoscheduleresourceinboththetimeand

frequencydomainusingresourceblockconceptofOrthogonalFrequencyDivisionMultiple

Access(OFDMA)asshowninfigure2.2and2.3.OFDMAallowssubsetsofthesubcarrierstobe

allocateddynamicallyamongthedifferentusersonthechannelasshownbelow.


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Figure2.2:schedulingconceptinOFDM

Thecoreofthetransmissionaccessschemeistousesharedchanneltransmission.Ascheduler

canvaryresourcesforeachtimeinstantandbywhichusersthesharedresourcesshouldbe

assigned.Thepossibilityforchanneldependentschedulinginthefrequencydomainisuseful

whenchannelsarevarying.Schedulingdecisionscanbetakenasoftenasonceevery1msand

thegranularityinthefrequencydomainis180kHz.Inthefrequencydomainthedownlink

subcarriersaregroupedintoresourceblocks,witheachresourceblockconsistingof12

consecutivesubcarriers(12*15KHz=180KHz).

Inaddition,toaccommodatedifferentspectralregulationsandavailability,LTEisdesignedto

supportvariablechannelbandwidthbyvaryingthenumberofsubcarriersusedfortransmission.

Thesubcarrierspacingisconstantregardlessofthetransmissionbandwidth.Toallowfor

operationindifferentlysizedspectrumallocations,thetransmissionbandwidthisinsteadvaried

byvaryingthenumberofOFDMsubcarriers.Subcarriersaregroupedas12consecutivepairs

knownasresourceblock.TheconceptofResourceBlockisexplainedinchapter3.

Channel bandwidthBWChannel[MHz]

1.4 3 5 10 15 20

No of Resource Block(180KHz)

6 15 25 50 75 100

Table 2.1 Transmission bandwidth configuration


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LTEcanalso bedeployed indifferentfrequencybands fromaslowas450MHzbandupto,at

least,2.6GHzwithsupportforbothFrequecyDivisionDuplex(FDD)andTimedivisionDuplex

(TDD).Thereisnospecified FFTsizeandsamplingfrequencyfortheLTEdownlink.The

samplingratefs=_fNFFTisoftena multipleorsubmultipleof3.84MHzwhichcorrespondsto

the chiprateinWCDMA.

Figure2.3:OFDMSignalrepresentedinFrequencyTimedomain

2.2.UplinkTransmission

TheuplinkaccessinLTEusesSingleCarrierFrequencyDivisionMultipleAccess(SC

FDMA).Comparedtothedownlink,thereissignificantlowerpoweravailabilityintheuplink.SC

FDMAwaschosenbecauseitcombinesthelowpeaktoaverageratio(PAR)techniquesofsingle

carriersystemswiththemultipathresistanceandflexibleallocationthatOFDMAoffers.SC

FDMAcanbeseenasanOFDMmodulationthatisprecededbyaDiscreteFourierTransform

(DFT)operation,hencetheyaresometimesreferredtoasDFTSOFDM.InSCFDMA,data

symbolsinthetimedomainareconvertedtothefrequencydomainusingdiscreteFourier

transform(DFT),inthefrequencydomaintheyaremappedtothedesiredlocationintheoverall

channelbandwidthbeforebeingconvertedbacktotimedomainusinganinverseFFT(IFFT)

.Cyclicprefixisthenaddedtothetimedomainsignal.

UplinkLTEisbasedonorthogonalseparationofusers.Itisthetaskoftheuplinkschedulerto

assignresourcesinbothtimeandfrequencydomaintodifferentusers.Mobiledevicesare

allowedtotransmitwithinacellduringagiventimeintervalbythescheduler.Onlyacontiguous

frequencyregioncanbeassignedtotheterminalsintheuplinkasaconsequenceoftheuseof

singlecarriertransmissionin LTEuplink.ThisisoftenreferredtoaslocalizedDFTSOFDM

transmission.Ablockdiagramshowingthetransmitterstructureandthedifferencebetween

OFDMandSCFDMAisdepictedinfigure2.4andfigure2.5respectively.

Sub-carriersFFT

Time

Symbols

5 MHz Bandwidth

Guard Intervals

Frequency


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DFTSub-carrierMapping

CPinsertion

Size-NTX Size-NFFT

Coded symbol rate= R

NTXsymbols

IFFT

Figure2.4:TransmitterstructureforSCFDMA.

Figure2.5:Differencesbetween SCFDMAandOFDM


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Chapter3 PhysicalLayerOverviewofLTE

AlthoughLTEdownlinkanduplinkusesadifferentmultipleaccessschemes,OFDMAandSC

FDMArespectively,theyshareacommonframestructure.Theframestructurerepresentsa

timedomainrepresentationoftheslotandsymbol.

Thesizeofvariousfieldsinthetimedomainisexpressedasanumberoftimeunit,

FFTsizeKHzT 2048150001s seconds.Thisischosenforbackwardcompatibilitywith

UMTS.(UMTSchiprate is3.84MHz oneeighthoftheassumedLTEsamplingfrequency).

Downlinkanduplinktransmissionsareorganizedintoradioframesofsize10ms(

ms10307200 sf TT ).Atype1framestructureisdefinedforFDD,whiletype2isdefinedfor

TDD.ForFDD,10subframesareavailablefordownlinktransmissionand10subframesare

availableforuplinktransmissionsineach10msinterval.Uplinkanddownlinktransmissionsare

separatedinthefrequencydomain.Eachradioframeis ms10307200 sf TT longandconsists

of20slotsstartingfrom 0to19,with length ms5.0T15360 sslot T .

Figure3.1:FDDFrameStructure

ForTDD,Eachradioframeoflength ms10307200 sf TT consistsoftwohalfframesoflength

ms5153600 s T each.Eachhalfframeconsistsoffivesubframesoflength ms107203 s T .For

eachsubframeinaradioframe,Ddenotesthesubframeisreservedfordownlink

transmissions,UdenotesthesubframeisreservedforuplinktransmissionsandSdenotesa

specialsubframewiththethreefieldsDwPTS,GPandUpPTS..ThelengthofDwPTSandUpPTS

variesanditssubjecttothetotallengthofDwPTS,GPandUpPTSbeingequalto ms107203 s T .


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Figure3.2:TDDFrame (for5msswitchpointperiodicity).

10msradioframerepresentsthelargestunitoftime.Thisisfurtherdividedintoasubframeof1

mswhichcontainstwo0.5msslots.AslotcontainssevenOFDMsymbolswhennormalcyclic

prefixisusedandsixOFDMsymbolswhenextendedcyclicprefixisused.WhennormalCPis

used,theCPlengthforthefirstOFDMsymbolineachslotisslightlylongerthanthatofthe

othersixtoaccommodateanintegernumberofOFDM.Thisimpliesthatasubframe(1ms)

consistsof14OFDMsymbols(inthecaseofnormalCP)and12OFDMsymbolinthecaseof

extendedCP.

Inthefrequencydomain,resourcesaregroupedintoresourceblocksmadeupof12consecutive

subcarriersperslot,thiscorrespondstoabandwidthof180Khz.TheResourceElementdepicts

thesmallestunitofresource,madeupofonesubcarrierforadurationofoneOFDMsymbol.A

Resourceblockisthusmadeupof84resourceelementswhennormalCPisusedor72resource

elementinthecaseofextendedCP.(12x7ofdm/slotand12x6ofdm/slotrespectively).Thisis

showninfigure3.3


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Figure3.3: OFDMresourceblockconcept


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3.1DownlinkPhysicalLayeroverview

InLTE,theenhancedbasestationthatprovidesphysicallayerfunctionalityisreferredtoas

evolvedNodeB(eNodeB).Thephysicallayerisprimarilyresponsiblefortranslatingdataintoa

reliablesignalbetweentheeNodeBandtheUserEquipment(UE).Thephysicallayeralso

interfaceswiththehigherlayers,specificallywiththeMAClayerviatransportchannels.DataisdeliveredtothephysicallayerintheformofTransportBlocksthatareofcertainsize.

ScramblingModulation

mapper

Layermapper

Precoding

Resource

elementmapper

OFDMsignal

generation

Resource

elementmapper

OFDMsignal

generationScrambling

Modulation

mapper

layersantenna

portscodewords

Figure

3.4:

Overview

of

downlink

physical

channel

processing.

Toreducetransmissionerrors,a24bitCyclicRedundancyCheck(CRC)andchannelcodingare

appendedtoeachblockofdata.TheCRCisusedatthereceivertodetecterrorsinthedecoded

transportblock.Inaddition,scramblingisappliedtoalldownlinkphysicalchannelstoreduce

interferencerejection.Thescramblingsequenceusesanorder31Goldcode,whichcanresultin

231sequencesthat arenotcyclicshiftsofeachother.QuadraticPermutationPolynomial(QPP)

basedTurbocodingisusedinLTEwithanoverallcoderate(R)of1/3.AQPPbasedreducesthe

complexityoftheTurboencoder/decoderbecausetheyaremaximumcontentionfree,which

impliesthattheyprovidemaximumflexibilityinsupportedparallelism.ForexampleifK=512,

supportedparallelismfactorswill include{1,2,4,8,16,32,64,128,256,512}.Trellis

terminationisusedfortheturbocoding.

LTEemploysabitlevelscramblingonalltransportchannels.Theblockofbitsundergoesan

exclusiveoroperationwithabitlevelscramblingsequence.Scramblinghelpsthereceiverto

fullyutilizetheprocessinggainbyreducinginterferenceatthereceiver.Differentscrambling

sequencesareusedindifferentneighboringcellthusrandomizinginterferingsignalsatthe

receiverafterdescrambling. MBSFNbasedtransmissionusescellcommonscrambling,the

samesequenceisusedinallparticipatingcells.

Themodulationmappertakesblockofscrambled binarydigits,0or1,asinputandoutputsa

complexvaluedmodulationsymbols,x=I+jQ.LTEsupportsthefollowingmodulationschemes;

QPSK,16QAMand64QAM.InthecaseofQPSK,twobitsarerepresentedby1symbol,whilein

16QAMand64QAMfourandsixbitsarerepresentedpersymbolrespectively.Notallchannels

supportsthethreemodulationscheme.Forexample,whiletheDownlinkSharedChannel(DL

SCH)supportsallthreemodulationschemes,BroadcastChannel(BCH)onlysupportsQPSK.


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Layermappingandprecoding arepartofantennamappingprocessandtheyrelatetoMultiple

InputMultipleOutput(MIMO)application.TheconceptofMIMOisusedinLTEandLTE

Advancedandisdiscussedinchapter5.Splittingantennamappingintotwosteps makesit

easiertodescribethedifferentMIMOschemesthatareusedinLTE.Thelayermappingprovides

demultiplexingofthemodulationsymbolsofeachcodewordintooneormultiplelayers.The

numberoflayersisalwaysasleastasmanyasthenumberoftransportblockstobetransmitted.

Precodingtakessymbolsfromeachlayerthatwasproducedfromlayermapping,andprocesses

themtogether.Theresultisthenmappedtodifferentsubcarriers(frequencydomain)and

antennaport(spatialdomain).

MIMOsystemsaredefinedintermsofthenumberoftransmitterandthenumberofreceivers.

Forexample,a4x2MIMOimpliesthereare4transmittersand2receivers.A2x2MIMOsystem

hasequalnumberoftransmitterandreceiver(2Transmitterand2Receivers)resultingina1:1

relationshipwithrespecttolayersandthetransmittingantennaport.However,a4X2hasa2:1

relationshipresultinginredundancyinoneorbothdatastreams.Layermappingspecifieshow

theextratransmitterantennasareused.Themappingconfigurationemployeddependsonthe

multiantennaschemethatisbeingused.

3.2UplinkPhysicalLayer overview

Asmentionedinsection2.2,uplinktransmissionisbasedonSCFDMA.CRCinsertion,Channel

codingandbitlevelscramblingaresimilartothedownlinkphysicallayerdescribedinsection

3.1.Uplinkscramblingishowevermobileterminalspecific,thusdifferentterminalsusedifferent

scramblingsequence.LTEUplinkalsosupports QPSK,16QAMand64QAMmodulationscheme.

Figure3.5:Overviewofuplinkphysicalchannelprocessing.


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Chapter4 PhysicalChannelsandSignals

Thephysicalchannelsintheuplinkanddownlinkoperatedifferentlyduetothedifferent

requirementsandconstraints.Thedownlinkphysicalchannelcorrespondstoasetofresource

elementscarryinginformationoriginatingfromhigherlayerssuchastheMAClayer.Dataona

transportchannelisorganizedintotransportblockswithinaTransmissionTimeInterval(TTI).EachtransportblockhasaTransportFormat(TF)thatspecifieshowthetransportblockistobe

transmittedovertheradiointerface.Suchspecificationincludes,themodulationscheme,block

size,ratecontrolandantennaemapping.

4.1DownlinkPhysicalChannels

Thefollowingdownlinkphysicalchannelsaredefined;

PhysicalBroadcastChannel,PBCH

PhysicalDownlinkSharedChannel,PDSCH

PhysicalMulticastChannel,PMCH

PhysicalDownlinkControlChannel,PDCCH

PhysicalControlFormatIndicatorChannel,PCFICH

PhysicalHybridARQIndicatorChannel,PHICH

ThefollowingphysicalsignalsareusedinLTEdownlink;

Primarysynchronizationsignal

Secondarysynchronizationsignal

Referencesignals

PhysicalBroadcastChannel(PBCH)

Thephysicalbroadcastchannelcarriescellspecificsysteminformationthatareusedto

configureandallowaccesstootherchannelsneededinthecell.Itistransmittedinthecenterof

thechannelandoccupies72subcarriers(equivalentto6RB).Inthetimedomain,thePBCHis

locatedinslot1ofthefirstfourOFDMsymbols.Theonlymodulationschemesupportedis

QPSK.

PhysicalDownlinkSharedChannel(PDSCH)

DownlinkdataistransmittedviathePDSCHchannel.ThechannelissharedamongmultipleUEs

inthetimedomain.LTEfeaturessuchasspatialmultiplexing,rateadaptationandchannel

dependentschedulingaresupportedinthischannel.UnlikePBCH,themodulationscheme

supportedareQPSK,16QAMand64QAM.


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PhysicalMulticastChannel(PMCH)

ThischannelisresponsiblefortransportingMulticastChannel(MCH).Italsosupports

QPSK,16QAMand64QAM.

PhysicalDownlinkControlChannel(PDCCH)

PDCCH carries the channelallocationand control information. It ismadeupofoneormore

consecutiveControlChannelElements (CCEs),whereacontrolchannelelement ismadeupof

nine resourceelementgroups.OnlyQPSKmodulation is supported in this channel.AControl

FormatIndicator(CFI)thatiscarriedbythePhysicalControlFormatIndicatorchannel(PCFICH)

indicatesthenumberofOFDMsymbolthatisallocatedforthePDCCH.

PhysicalControlFormatIndicatorChannel(PCFICH)

ThePhysicalControlFormatIndicatorchannel(PCFICH)isthephysicalchannelthatcarriesthe

CFIwhichdictatesthenumberofOFDMsymbolsusedfortransmissionofPDCCHina

subframe.ItislocatedatOFDMsymbol0ofeverysubframe.Inthefrequencydomain,thesub

carriersallocatedforPCFICHisdeterminedbyCellIDinformation.

PhysicalHybridARQIndicatorChannel,PHICH

AcknowledgementandNegative Acknowledgement(ACKandNAK) aresenttotheUEviathe

PHICH.

Figure4.1Transportchannelsmappedtophysicalchannelsinthedownlink


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4.2DownlinkPhysicalSignals

Onthedownlink,LTEdefinesthreephysicalsignals;

PrimarySynchronization

SecondarySynchronization

ReferenceSignals

Theprimaryandsecondarysynchronizationsignalsarespecificsequencesinsertedintothelast

twoOFDMsymbolsinthefirstslotofsubframeszeroandfive.Theyaremainlyusedforcell

searchprocedure.Inadditiontotheprimaryandsecondarysynchronizationsignals,thecell

searchprocedurealsoexploitsthereferencesignalsaspartofitsoperation.Inthetimedomain,

boththeprimaryandsecondarysignalsaretransmittedtwiceper10msradioframe.Inthe

frequencydomain,thesignalsalwaysoccupythecentral62subcarriersofthechannel.This

ensuresthecellsearchprocedureisthesameregardlessofthechannelbandwidth.TheUE

determinesthetimingandcenterfrequencyfromthePrimarysynchronizationsignal.

Theprimarysynchronizationsignalsinthesubcarriersaremodulatedusingafrequencydomain

ZadoffChusequence.AZadoffChusequenceisaConstantAmplitudeZeroAutocorrelation

(CAZAC)sequencewaveformwithexcellentautocorrelationpropertiesandlowcrosscorrelation

withothersequences.Whenappliedtoradiosignals,itresultsinanelectromagneticsignalof

constantamplitude.Thephaseofeachsubcarrierisdeterminedbytherootindexnumberina

sequencegeneratorwiththerootindexnumbercorrespondingtothecellidentity.Thereare

504uniquecellidentitiesandthepowerlevelineachsubcarriersarethesame.

Thesecondarysynchronizationsignalisusedtoidentifythecellidentitysubgroups.Its

frequencyrepresentationissimilartotheprimarysynchronizationdescribedabove.The

sequencegenerationfunctionutilizesaninterleavedconcatenationoftwolength31binary

sequence.The504uniqueidentitiesmentionedintheparagraphaboveisgroupedinto168

uniquecellidentitygroups(from0to167),witheachgroupcontainingthreeuniqueidentities.

Thelaterisachievedbycyclicshiftingeachsequence.Theprimarysynchronizationgivesthe

identityinformation.

Referencesignalsareusedtoreducethepossibilityofamplitude,phaseandtimingerrorsinthe

receivedsignals.Sucherrorsmighthavebeenintroducedbytheradiochannelandimpairments

fromthetransmitter.Thereferencesignalsdonotcarryanyuniqueinformationbutprovides

knownphaseandamplitudereferencethatcanbeusedtoreliabledecodesignalsthatwould

havebeenerroneouslydecodedinitsabsence. Inthetimedomain,thereferencesignalsare

generatedeverytwosymbolsperslotwhileinthefrequencydomain,theyareallocatedinevery

sixthsubcarriers.Inadditiontocellspecificreferencesignals,LTEdefinesMBSFNreference

signalsandUEspecificreferencesignals.


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4.3UplinkPhysicalChannel

Thefollowingphysicalchannelsareusedintheuplink;PhysicalUplinkSharedChannel(PUSCH),

PhysicalUplinkControlChannel(PUCCH)andthePhysicalRandomChannel(PRACH).

PUSCHisthechannelthatcarriesusertraffic.SimilartothePDSCH,themodulationscheme

supportedareQPSK,16QAMand64QAM.UplinkSharedChannel(ULSCH)andUplinkControl

information (UCI)arealsotransportedviathischannel.PUCCHcarriesuplinkcontrol

Informationsuchasschedulingrequests,periodicChannelQualityIndicator(CQI),and

acknowledgements.RandomaccesspreamblessenttoeNodeB isinitiatedvia thePRACH.It

shouldbenotedthataUEcannottransmitonbothPUCCHandPUSCHsimultaneously.This

impliesthatiftheUEneedstosenddatainthesamesubframeasthescheduledperiodicCQI

report,PUSCHwouldbeusedinsteadof PUCCH.

Figure4.2TransportchannelsmappedtophysicalchannelsintheUplink

UplinkPhysicalSignals

4.4UplinkPhysicalSignals

LTEdefinestwophysicalsignalsintheuplink,namelyDemodulationReferencesignal(DMRS)

andtheSoundingReferenceSignal(SRS).DMRSisusedforuplinkchannelestimationand

synchronization.ItfacilitatescoherentdemodulationbasedontheZadhoffChusequence,

whichprovidesitwithgoodtimedomainautocorrelationpropertiesandconstantamplitude.In

thefrequencydomain,itisthesamesizeastheassignedresource,whileinthetimedomain;it

istransmittedinthefourthSCFDMAsymbolofthePUSCHslot.SRSisalsobasedonthe

ZadhoffChusequenceanditsusedtofacilitatefrequencydependentscheduling.Subcarrier

allocationisdictatedbythebandwidthallocationconfiguredintheSRS.


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Chap

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rank

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IMOisappli

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23

Figure5.2Closedloopspatialmultiplexingusing NantennaandMlayers

TheclosedloopspatialmultiplexingrequirestheUEtofeedbacktherankindicator(RI),thePMI

andthechannelqualityindicatorCQIintheuplink.TheRIindicatesthenumberofspatiallayers

thattheUEscurrentchannelconditioncansupport.TheeNodeBmaydecidethetransmission

rank(M)basedontheRIreportedbytheUEorbasedonotherfactorssuchasavailablepower

transmission.The eNodeBsendsthescheduledUEtheintendedprecodingmatrix,thatwould

beusedaspartofthedownlinkcontrolinformationusingathreebitTransmitPrecodingMatrix

Indicator(TPMI)fieldfortwotransmitantennasandasixbitTPMIfieldforfourtransmit

antennas.Withoutcyclicdelaydiversity(CDD),precodingforspatialmultiplexingisdefinedby

)(

)(

)(

)(

)(

)1(

)0(

)1(

)0(

ix

ix

iW

iy

iy

P

Ydenotesthecomplexsymboltransmittedonthenthantenna,xdenotesthemodulation

symboltransmittedonthemthlayerandWdenotestheNXMprecodingmatrix.For

transmissionontwoantennaports, 1,0p ,theprecodingmatrix )(iW oftable5.1isused

whilefor transmissiononfourantennaports, 3,2,1,0p ,theprecodingmatrixtable5.2is

employed.


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24

Codebookindex

Number of layers

1 2

0

1

1

2

1

10

01

2

1

1

1

1

2

1

11

11

2

1

2

j

1

2

1

jj

11

2

1

3

j

1

2

1 -

Table 5.1: Codebook for transmission for Two antenna ports 1,0 .

Codebookindex

nu Number of layers

1 2 3 4

0 Tu 11110 }1{

0W 2}14{

0W 3}124{

0W 2}1234{

0W

1 Tjju 111 }1{

1W 2}12{

1W 3}123{

1W 2}1234{

1W

2 Tu 11112 }1{

2W 2}12{

2W 3}123{

2W 2}3214{

2W

3 Tjju 113 }1{

3W 2}12{

3W 3}123{

3W 2}3214{

3W

4 Tjjju 2)1(2)1(14 }1{4W 2}14{4W 3}124{4W 2}1234{4W 5 Tjjju 2)1(2)1(15

}1{5W 2

}14{5W 3

}124{5W 2

}1234{5W

6 Tjjju 2)1(2)1(16 }1{

6W 2}13{

6W 3}134{

6W 2}1324{

6W

7 Tjjju 2)1(2)1(17 }1{7W 2}13{7W 3}134{7W 2}1324{7W 8 Tu 11118

}1{8W 2

}12{8W 3

}124{8W 2

}1234{8W

9 Tjju 119 }1{

9W 2}14{

9W 3}134{

9W 2}1234{

9W

10 Tu 111110 }1{

10W 2}13{

10W 3}123{

10W 2}1324{

10W

11 Tjju 1111 }1{

11W 2}13{

11W 3}134{

11W 2}1324{

11W

12 Tu 111112 }1{

12W 2}12{

12W 3}123{

12W 2}1234{

12W

13 Tu 111113 }1{

13W 2}13{

13W 3}123{

13W 2}1324{

13W

14 Tu 111114 }1{

14W 2}13{

14W 3}123{

14W 2}3214{

14W

15 Tu 111115 }1{

15W 2}12{

15W 3}123{

15W 2}1234{

15W

Table 5.2 Codebook for transmission for Four antenna ports 3,2,1,0 .


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Theprecodingcodebooksshownabovearedesignedtohaveconstantmodulus,thusallphysical

transmitantennakeepthesametransmitpowerlevelregardlessoftheprecodingmatrix.This

ensurestheefficiencyofthepoweramplifier.Theprecodingmatrixesarenested,thatis,each

precodingmatrixinahigherranksubcodebookcanfindatleastoneprecodingmatrixinalower

rankprecodingmatrix.ThispropertyensuresproperperformanceincaseswhentheeNodeB

decidestousetransmissionrankthanwhatisindicatedintheRI.

Openloopspatialmultiplexingareused insituationwhenthefeedbackreceivedfromtheUEis

unreliable,forexamplewhentheUEismovingatafastspeedcausingchannelconditiontovary

fasterthanthefeedbackcanreport.Theopenloopisillustratedinthefigurebelowconsistingof

NantennasandMlayerswithNgreaterorequaltoM.

Figure 5.3: Open-loop spatial multiplexing with Nantennas and Mlayers.

UnlikeSUMIMO,MUMIMOschemeissupportedinboththedownlinkanduplinkLTE.Inthe

uplink,TwoormoreUEscanbescheduledtotransmitusingthesametimefrequency.Tomake

eachsignalunique,theeNodeBassignsorthogonalreferencesignalstotheschedulesUEs.A

ZadoffChusequenceisdefinedasthebasesequencefortheuplinkreferencesignals.

OrthogonalreferencesignalscanbecreatedfromthecyclicallyshiftedZadofffChusequence.

ThuseachUEcanbeassignedadifferentcyclicallyshiftedZadofffChusequence,resultingin

uniquereferencesignalforeachUE.Fordatatransmissionontheuplink,acyclicshiftvalueis

alwaysincludedinthecontrolsignalandneedstobereceivedbeforeaUEcanstarttransmitting

data.ThisistrueevenincaseswhereMUMIMOschemeisnotused.

Rank1transmissionistheonlymodesupported inthedownlinkwhenMUMIMOschemeis

used.Differentrank1precodingmatricesareusedwhenmultipleUEsareconfiguredtousethe

sametimefrequencyresource.PerUEpreconfiguredPowerlevelmightbehardtomaintainin

MUMIMO,hencetheneedtointroduceda1bitsignalingtoindicateiftheUEneedstoreduce

itspowerby half(3dB).

TransmitdiversityisanotherMIMOschemeusedinLTEandLTEAdvanced.Inthedownlink,the

diversityschemecanbeappliedtoallthephysicalchannels,notjustthePDSCH.TheUE

recognizesthenumberoftransmitantennabyblindlydecodingthePBCH.Spacefrequency


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blockcode(SFBC)isusedinthecaseoftwotransmitantenna.ForeasierUEimplementationand

toproviderobustnessagainstcorrelationbetweenchannelsfromdifferenttransmitantennas,a

combinationofSFBCandfrequencyswitchedtransmitdiversity(FSTD)isusedinthecaseoffour

transmitantenna.Thisisshowninfigure5.4and5.5below.

Figure5.4:SFBCwithtwotransmitantennasondownlink.

Figure5.5:SFBC+FSTDwithfourtransmitantennasondownlink


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Chapter6:Other LTEAdvancedTechnologies

6.1carrieraggregation

CarrieraggregationtechnologyisintroducedinLTEAdvanced tosupportveryhighdatarate

transmissionsovera wider frequencybandwidthsthanexistingLTEsupports.LTErel8as

showninTable2.1,supportsabandwidthrangingfrom1.4Mhzto20Mhz,whileLTEAdvanced

should supportabandwidthextensionupto around100MHz.Inorder tosupportawider

transmissionbandwidth whilepreservingbackwardcompatibilitywithLTERel8,Carrier

aggregationtechniquehasbeenintroduced.Itinvolvestheaggregationofmultiplebasic

frequencyblockscalledcomponentcarriers(CC)witheachCChavingamaximumof110

resourceblocks(RBs)(whichissupportedintheLTERel8).Otherradioparameterssuchasthe

subcarrierspacing,subframelengthandphysicalchannelparameters thatwasdiscussedin

previouschapters,remainsthesameacrossCCs.ThisistoensureallLTEandLTEAdvancedUEs

canworkinthesamenetwork.

Figure6.1carrieraggregationtechniques

TwotypesofCarrieraggregationtechniquesarebeingproposedforLTEAdvanced;Continuous

andNoncontinuous.Continuouscarrieraggregationinvolvesusingmultipleavailable


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componentcarrierthatareadjacenttoeachotherwhiletheNoncontinuousaggregation

techniquesinvolvesusingcomponentcarriersthatareseparatedalongthefrequencyband.

WhileContinuouscarrieraggregationwouldseemeasiertoaccomplished,mostservice

providersmightfindithard(ifnotimpossible)toobtaincontinuous100MHzfrequencyband

duetothescarcityinspectrumallocation.WithNoncontinuousCarrierAggregationtechnique,

dataistransmittedovermultipleseparatedcarriersacrossalargefrequencyrangewith

differentchannelcharacteristics.Noncontinuouscarrieraggregationschemecanbe

implementedeitheratthemediumaccesscontrol(MAC)orthePhysicallayer.Ifimplementedin

theMAClayer,transmissionparametersareconfiguredindependentlyforeachcomponent

carrier.Thisimpliesthateachcomponentcarriermaintainsitsowntransmissionconfiguration

parameters(suchasthemodulationscheme,codingrateandMIMOconfiguration)inthe

physicallayeraswellasintheMAClayer.Inthephysicallayeraggregationscheme,asingleMAC

entityisusedbyalltheaggregatedcomponentcarriers.BackwardcompatibilityforLTERel8 is

ensuredbyusingthesameconfigurationparametersandschemes.

Figure6.2 ExampleofLTEcarrieraggregationscheme

Tosupportasymmetricdatatrafficintheuplinkanddownlink,anumberofschemeshavebeen

proposedtoaidtheeNodeBinidentifyingtheexactcomponentcarriersthataUEhasselected

forthedownlink.Thefirstschemeproposestheconfigurationofaphysicalrandomaccess

channel(PRACH)oneachcomponentcarrierwithdifferentparameters.TheeNodeBcanextract

thenumberofcomponentcarriersthattheUEisusingfromRACHpreambleviaanuplink

componentcarrier.Thesecondschemeinvolvestheconfigurationon allthedownlink

componentcarrierswiththesamePRACHparameters.Allassociateddownlinkcomponent

receivesabroadcastviaaninitialrandomaccessresponsewithspecifictransmission


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configuration.TheeNodeBcanthenextractthecomponentcarriersthatarebeingusedbythe

UE.A thirdschemeissimplebutlessflexible.Itusesonlyonedownlinkcomponentcarrierto

bearthecontrolchannelsrelevanttotherandomaccessprocess.Withthisschemeinuse,the

eNodeBdoesnot havetodetectthedownlinkcomponentcarriersthatareinusebythe UE.

6.2 CoordinatedMultipointTransmission/Reception

CoordinatedMultipointTransmissionandReception(CoMP) isanothercandidatetechnology

being consideredforLTEAdvanced.CoMPinvolvestheuseofantennasfrommultiplecellsites

inacoordinatedfashion.Bycoordinatingtransmissionbetweenmultipleantennas,higher

systemcapacityandimprovedcelledgedataratecanbeachieved.Beamformingorprecoding

gainscanbeachieved by takingintoaccounttheinstantaneouschannelconditions.Thereare

twocategoriesforcoordinatingmultipleantennas;Dynamicschedulingcoordinationand Jointtransmission/reception.CoMPcanbeusedwithinacelloracrossmultiplecells.

Figure6.3:IntraandInterCoMPconcept

InIntrasiteCoMP,thecoordinationiswithinthecellandlesscomplex,whileinIntersiteCoMP

thecoordinationcanspanacross2ormorecells,thusitisconsideredmorecomplexwith

respecttotheformer.

ChannelestimationonthedownlinkcanbeobtainedusingUEspecificreferencesignalsorcell

specificreferencesignal.InthecaseofUEspecific,referencesignalissubjecttothesame


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transmittersideprecodingasthedata,beforetransmittingfrommultipleantenna.TheUEdoes

notneedtobeawareofthetransmissionpointsinvolved,hencethismethodcanbeusedin

existingLTErel8.Inaddition,standardizedcodebookordifferentdeploymentscenariosarenot

needed.

Figure6.4:demodulationbasedonUEspecificRS

Withcellspecificreferencesignals,theUEneedstotakeintoaccounttheweightsappliedatthe

differenttransmissionpoints.Thisimpliestheuseofstandardizedtransmissionweightsand

codebooks.Maximumratiocombinationandinterferencerejectioncombiningcanbeusedto

coherentlycombinesignalsintheuplink.Onthetransmitterside,theknowledgeofthechannel

isalsousedtodeterminetheCoMPprocessing.The UEcanreportthequalityofthenetwork

usingtheCQIwiththeaidofreferencesignals.

Figure6.5:demodulationbasedoncellspecificRS


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6.3 Relaying

Arelayutilizesmultihopcommunication toenhancethetargeteddatarateinLTEAdvanced.

Fromalinkbudgetperspective,reducingthedistancebetweenthetransmitterandreceivercan

increasethepowerrate.Severalrelaytechniqueshavebeendevelopedoverthepastdecades

suchastheanalogrepeater,thatusesacombinationofdirectionalantennasandpower

amplifierstorepeatthetransmitsignal.Thefirstcommercialwirelessnetworktoincorporate

multihopcommunicationwasIEEE802.16j.InLTEAdvanced,threerelaytechniquesarebeing

considered;onewayrelay,twowayrelay,andsharedrelay.

Onewayrelaymodelismadeupofonesingleantennarelaypersectorsservingonlyusersinits

sector.Communicationtakesplaceintwoorthogonalphases,thefirstphasebeingtheeNodeBs

transmissiontotherelay,whilethesecondphaseinvolvestherelaystransmissiontotheUE.A

decodeandforwardoperationisthenperformed.Onewayrelaycanenhancecapacitynearthe

celledgebutmightbelimitedbyinterference.

Figure6.6:Onewayrelaymodel

Twowayrelaymodelalsocalledbidirectionalrelayingismadeupofasingleamplifyand

forwardrelaypersectorandallowsimultaneousuplink/downlinkcommunication.Twoway

relaymodelavoidsthehalfduplexlossofonewayrelaybecausebothUEandeNodeBtransmit

totherelayatthesametimeinthefirsttimeslot.Therelaythenrebroadcastduringthe

secondslot,hencecommunicationstilltakesplaceintwoorthogonalphase.DownlinkanduplinkratecanbemaximizedwithTwowayrelaymodelduetothefullduplexadvantage.With

theaidofchannelstateinformationandknowledgeoftheirownmessages,theUEandeNodeB

areabletodecodeinformationfromanotherparty.Duetoamplifyandforwardnatureoftwo

wayrelaying,ithasapotentialtoamplifyinterference.


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Figure6.7:Twowayrelaymodel

SharedrelayusesapointtomultipointtechniquewhereseveraleNodeBcansharetherelay.

SimilartoOnewayrelay,itusesadecodeandforwardmechanism,howevermultipleantenna

relayareplacedattheintersectionofmultiplecells.Therelaythendecodesthesignalsfromthe

intersectingbasestations.Interferencecanbecanceledbyusingmultiplereceiveantennaswith

MIMOtechnologies.ExploitingtheMIMOMAC(multipleaccess)channeltodecodethree

signalscochannelandthenusingMIMObroadcastchanneltodeliverthreeinterferencefree

signals.Thiswouldresultinthe removalof muchofthedominantinterference.Byspatially

removinglocalinterference,sharedrelayensuresthehighestratewhencomparedtotheother

relaymethodsthatwaspreviouslydiscussed.

Figure6.8:Shared relaymodel

Figure6.9:Powercomparisonanalysiswithdifferentrelaytechniques


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Conclusion

ThereportlookedatthephysicallayerinLTEandsomecandidatetechnologyproposedinLTE

Advanced.BackwardcompatibilitywithLTErel8isanimportantpriorityindevelopingLTE

Advanced.Withregardstocarrieraggregation,thisimpliesthatUEsincapableofsupporting

LTEAdvancedmustbeabletodemodulateanddecodethedownlinkdatachannelfromoneof

thecomponentcarrierswithoutperformanceloss.Asdiscussedinsection6.1,therearetwo

methodsproposedforcarrieraggregation;continuousandnoncontinuous.Forcontinuous

spectrumallocation,theUEmightbeaffectedbyinterferencefromadjacentcomponent

carriers.Toavoidsuchcondition,Guardbandsmaybenecessarybetweenadjacentcomponent

carriers.Consequently,theneedforanintercarrierguardbandmayresultinlossin

transmissionbandwidth.Toaccountforthelossduetoguardbandandensurethe20MHz

transmissionbandwidthispreserved,theentiretransmissionbandwidthmightneedtobewider

than20MHz.


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References

1. 3GPP, TR 36.814, "Further Advancements for E-UTRA; Physical LayerAspects".

2. 3GPP, TR 36.913, "Requirements for Further Advancements for E-UTRA

(LTE-Advanced) (Release 8)".

3. LTE-Advanced Evolving LTE towards IMT-Advanced, Stefan Parkvall, Erik

Dahlman, Anders Furuskr, Ylva Jading, Magnus Olsson, Stefan Wnstedt,

Kambiz Zangi

4. HSPA to LTE-Advanced, Rysavy Research

5. Investigation on Optimum Radio Parameter Design in Layered OFDM for LTE-

Advanced, Kazuaki Takeda, Satoshi Nagata, Yoshihisa Kishiyama, Motohiro

Tanno, Kenichi Higuchi, and Mamoru Sawahashi

6. Device-to-Device Communication as an Underlay to LTE-Advanced Networks,

Klaus Doppler, Mika Rinne, Carl Wijting, Cssio B. Ribeiro, and Klaus Hugl, Nokia

Research Center

7. Long Term Evolution: Towards 4th Generation of Mobile Telephony and Beyond

Sao Tomai1, Grega Jaku2

8. Progress on LTE Advanced-the new 4G standard, Eiko Seidel

9. LTE The UMTS Long Term Evolution from Theory to Practice, Stefania

Sesia,Issam Toufik,Mathew Baker.

10. Overview of the 3GPP Long Term Evolution Physical Layer, Jim Zyren

11. 3G Evolution HSPA and LTE for Mobile Broadband, Erik Dahlman,StefanParkvall,Johan Skold and Per Beming.

12. UMTS Long Term Evolution (LTE) Technology Introduction: Application Note

1MA111, RHODE & SCHWARZ.

13. Technical Solutions for the 3G Long-Term Evolution Hannes Ekstrm et al.


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14. Carrier Aggregation for LTE-Advanced Mobile Communication Systems

Guangxiang Yuan et al

15. LTE-Advanced The solution for IMT-Advanced, Hideshi Murai, Maria

Edvardsson, Erik Dahlman

16. Illustration of MIMO channel matrix in a wireless communication system using

multiple transmitters (Tx) and receivers (Rx) , Benjamin Baumgrtner

17. LTE and the Evolution to 4G Wireless, Moray Rumney

A Technical Study of Long Term Evolution (LTE) and LTE-Advanced by Olufemi Amao

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