2002_EURASIP_Rayleigh fading multi-antenna channels.pdf

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1、RayleighFadingMulti-AntennaChannelsAlexGrantInstituteforTelecommunicationsResearchUniversityofSouthAustraliaMawsonLakesBoulevardMawsonLakesSA5095Australiaalex.grant@unisa.edu.auSubmittedtoEURASIPSpecialIssueonSpace-TimeCodingMay29,2001AbstractInformationtheoreticp

2、ropertiesof°atfadingchannelswithmultipleantennasareinvestigated.Perfectchannelknowledgeatthereceiverisassumed.Expressionsformaximuminformationratesandoutageprobabilitiesarederived.Theadvan-tagesoftransmitterchannelknowledgearedeterminedandacriticalthresholdisfound

3、beyondwhichsuchchannelknowledgegainsverylittle.Asymptoticexpres-sionsfortheerrorexponentarefound.Forthecaseoftransmitdiversityclosedformexpressionsfortheerrorexponentandcuto®ratearegiven.Theuseoforthogonalmodulatingsignalsisshowntobeasymptoticallyoptimalintermsofi

4、nformationrate.Keywords:Space-TimeChannels,TransmitDiversity,InformationTheory,ErrorExponents11IntroductionWirelessaccesstodatanetworkssuchastheInternetisexpectedtobeanareaofrapidgrowthformobilecommunications.Highuserdensitieswillrequireveryhighspeedlowdelaylinksi

5、nordertosupportemergingInternetapplicationssuchasvoiceandvideo.Eveninthelowmobilityindoorenvironment,thedeleteriouse®ectsoffadingandtheneedforverylowtransmitpowercombinetocauseproblemsforradiotransmissions.Regardlessofadvancedcodingtechniquessuchasturbo-codes[1],c

6、hannelcapacityre-mainsanunmovablebarrier(withoutyetconsideringine±cienciesintroducedbyhigherlayernetworkoverheads).Withoutchangingthechannelitselfnotmuchcanbedone.Fortunately,increasingthenumberofantennasatboththebaseandmobilestationsac-complishesexactlythat,resul

7、tinginchannelswithhighercapacity.Suchsystemscantheoreticallyincreasecapacitybyuptoafactorequalingthenumberoftransmitandreceiveantennasinthearray[2{6].Spatialdiversityhasbeenproposedforsupportofveryhighratedatauserswithinthirdgenerationwide-bandCode-DivisionMultipl

8、eAccess(CDMA)systemssuchascdma2000[7].Usingmultipleantennas,thesesystemsachievegainsinlinkqualityandthereforecapacity.Classically,diversityhasbeenexploi