外文翻译--基于MIMO-OFDM系统的正交空时分组码【适用于毕业论文外文翻译】.doc

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1、外文资料（一）OnOrthogonalSpace-TimeBlockCodesforMIMO-OFDMSystemsSpace-timecodeinmobilecommunicationsystem,andorthogonaldesinginmultiple-antennasscnemearedicsussed.Bythemethods,dataisencodedusingaspace-timeblockcodeandissplitintoseveralstreamswhicharesimultaneouslytransmittedbyantennas.Soamaximum

2、-likelihooddecodingalgorithmcanbeusedatthereceivertoachievethemaximumdiversityorderIntroductionMostworkonwirelesscommunicationshadfocusedonhavinganantennaarrayatonlyoneendofthewirelesslink—usuallyatthereceiver.SeminalpapersbyGerardJ.FoschiniandMichaelJ.Gans[1],Foschini[2]andEmreTelatar[3]e

3、nlargedthescopeofwirelesscommunicationpossibilitiesbyshowingthatforthehighly-scatteringenvironmentsubstantialcapacitygainsareenabledwhenantennaarraysareusedatbothendsofalink.Analternativeapproachtoutilizingmultipleantennasreliesonhavingmultipletransmitantennasandonlyoptionallymultiplerecei

4、veantennas.ProposedbyVahidTarokh,NambiSeshadriandRobertCalderbank,thesespace–timecodes(STCs)achievesignificanterrorrateimprovementsoversingle-antennasystems.TheiroriginalschemewasbasedontrelliscodesbutthesimplerblockcodeswereutilizedbySiavashAlamouti,andlaterVahidTarokh,HamidJafarkhaniandR

5、obertCalderbanktodevelopspace–timeblock-codes(STBCs)[4].STCinvolvesthetransmissionofmultipleredundantcopiesofdatatocompensateforfadingandthermalnoiseinthehopethatsomeofthemmayarriveatthereceiverinabetterstatethanothers.InthecaseofSTBCinparticular,thedatastreamtobetransmittedisencodedinbloc

6、ks,whicharedistributedamongspacedantennasandacrosstime.Whileitisnecessarytohavemultipletransmitantennas,itisnotnecessarytohavemultiplereceiveantennas,althoughtodosoimprovesperformance.ThisprocessofreceivingdiversecopiesofthedataisknownasdiversityreceptionandiswhatwaslargelystudieduntilFosc

7、hini's1998paper.AnSTBCisusuallyrepresentedbyamatrix.Eachrowrepresentsatimeslotandeachcolumnrepresentsoneantenna'stransmissionsovertime.Here,sijisthemodulatedsymboltobetransmittedintimeslotifromantennaj.TherearetobeTtimeslotsandnTtransmitantennasaswellasnRrecei