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基于导频的角域MIMO-OFDM信道估计的研究.docx

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基于导频的角域MIMO-OFDM信道估计的研究 Abstract: Multiple-inputmultiple-output(MIMO)systemsareakeytechnologyforwirelesscommunicationsystems.MIMOsystemscanusemultipleantennastoimprovetheperformanceofwirelesscommunicationandincreasethedatatransferrate.Orthogonalfrequencydivisionmultiplexing(OFDM)isusedinMIMOsystemstoreducetheinterferencecausedbymultipathfadingandimprovethequalityofthereceivedsignal.ChannelestimationisanimportantissueinMIMO-OFDMsystems.Inthispaper,weinvestigatethechannelestimationinaMIMO-OFDMsystembasedonpilotsignals. Introduction: MIMO-OFDMsystemshavebecomewidelyusedinwirelesscommunicationsystemsduetotheirhighefficiencyandhighdatatransferrate.InMIMO-OFDMsystems,multipleantennasareusedatthetransmitterandreceivertoenhancethesignalqualityandimprovethedatatransferrate.InOFDMsystems,thesignalsaretransmittedinparallelovermanysubcarriers,whichcanbeusedtotransmitmultipledatastreamssimultaneously. ChannelestimationisessentialinMIMO-OFDMsystemsbecausethechannelbetweenthetransmitterandreceiverchangesconstantlyduetomultipathfading,whichmeansthetransmittedsignalexperiencesdifferentdelaysandattenuationlevelsfrommultiplereflectionsofthesignal.AccuratechannelestimationiscrucialtoachievingreliablecommunicationinMIMO-OFDMsystems. Inthispaper,weinvestigatethechannelestimationinaMIMO-OFDMsystembasedonpilotsignals.Themainobjectiveofthispaperistoexploretheuseofpilotsignalsinchannelestimationandtocomparetheperformanceofdifferentpilotschemes. MIMO-OFDMChannelModel: TheMIMO-OFDMsystemcanbemodeledas: y=Hx+n whereyisthereceivedsignalvector,xisthetransmittedsignalvector,nistheadditivenoise,andHisthechannelmatrix. ThechannelmatrixHcanbedefinedas: H=[h1,1h1,2…h1,Nt h2,1h2,2…h2,Nt … hNr,1hNr,2…hNr,Nt] whereNtisthenumberoftransmitantennasandNristhenumberofreceiveantennas.hi,jrepresentsthechannelcoefficientbetweenthejthtransmitantennaandtheithreceiveantenna. ChannelEstimation: ChannelestimationistheprocessofestimatingthechannelmatrixHfromthereceivedsignalyandthetransmittedsignalx.InMIMO-OFDMsystems