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基于广义ABBA空时分组码的OFDM系统.docx

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基于广义ABBA空时分组码的OFDM系统 Abstract OrthogonalFrequencyDivisionMultiplexing(OFDM)isapopularmodulationtechniqueusedinmanywirelesscommunicationsystemsduetoitsabilitytocombatfrequency-selectivefadingandachievehighdatarates.ThispaperpresentsanovelapproachtoenhancetheperformanceofOFDMsystemsbyusingageneralizationofABBAspace-timeblockcodes(STBCs).Theproposedscheme,namedgeneralizedABBASTBCOFDM,combinestheadvantagesofbothSTBCsandOFDMtoimprovethesystem'sreliabilityandspectralefficiency. Introduction OFDMisamulti-carriermodulationtechniquethatdividestheentirebandwidthintomultiplesubcarriers,eachcarryingarelativelylowdatarate.ThisallowsOFDMtocombatfrequency-selectivefadingeffectively,makingitsuitableforwirelesscommunicationsystemsoperatinginenvironmentswithmultipathpropagation.However,theuseofmultiplesubcarriersalsoleadstoahighpeak-to-averagepowerratio(PAPR),whichcanimpactthepowerefficiencyofthesystem. ToovercomethelimitationsofOFDM,variouscodingtechniqueshavebeenproposedtoimproveitsperformance.Onepopularcodingtechniqueisspace-timeblockcoding(STBC),whichprovidesdiversitygainandimprovesthesystem'sreliabilityagainstfadingchannels.ABBASTBCisaspecificclassofSTBCthatexhibitsfulldiversity,meaningthatitcanachievethemaximumpossiblediversitygaininfadingchannels.However,traditionalABBASTBCisdesignedforsingle-inputsingle-output(SISO)systems,anditsapplicationtoOFDMsystemsisnontrivial. ProposedGeneralizationofABBASTBCOFDM TheproposedgeneralizedABBASTBCOFDMschemeextendstheapplicationofABBASTBCtoOFDMsystemsbyleveragingtheinherentstructureofOFDM.IntraditionalABBASTBC,thecodingmatrixisdesignedforSISOsystems,andthetransmittersendsacopyofeachsymboloneachtransmitantenna.InOFDMsystems,eachsymbolisdividedintomultiplesubcarriers,anddifferentsymbolsaretransmittedondifferentsubcarriers.Therefore,thecodingmatrixneedstobemodifiedtoaccommodatethesubcarrierstructureofOFDM. ThegeneralizedABBASTBCOFDMschemefirstconstructsacodingmatrixthatmaintainsthefulldiversitygainpropertyandextendsitusingthesubcarriersofOFDM.T