ChannelEstimationforWirelessOFDMsystems[1].pdf

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1、2NDQUARTER2007,VOLUME9,NO.2www.comsoc.org/pubs/surveysCHANNELESTIMATIONFORWIRELESSOFDMSYSTEMSMEHMETKEMALOZDEMIR,LOGUSBROADBANDWIRELESSSOLUTIONS,INC.ANDHUSEYINARSLAN,UNIVERSITYOFSOUTHFLORIDAABSTRACTOrthogonalfrequencydivisionmultiplexing(OFDM)isaspecialcaseofmulti-carriertransmissionanditcanac

2、commodatehighdataraterequire-mentofmultimediabasedwirelesssystems.SincechannelestimationisanintegralpartofOFDMsystems,itiscriticaltounderstandthebasisofchannelestimationtechniquesforOFDMsystemssothatthemostappro-priatemethodcanbeapplied.Inthisarticle,anextensiveoverviewofchan-nelestimationtec

3、hniquesemployedinOFDMsystemsarepresented.Inaddition,theadvantages,drawbacks,andrelationshipoftheseestimationtechniqueswitheachotherareanalyzedanddiscussed.Asthecombinationofmultipleinputmultipleoutput(MIMO)-OFDMsystemspromiseshigherdatarates,estimationtechniquesarefurtherinvestigatedfortheses

4、ystems.Althoughtheexistingproposedtechniquesdifferintermsofcomputationalcomplexityandtheirmeansquarederror(MSE)performance,ithasbeenobservedthatmanychannelestimationtechniquesareindeedasubsetofLMMSEchannelestimationtechnique.Hence,basedonagivensystem’sresourcesandspecifications,asuitablemetho

5、damongthepresentedtech-niquescanbeapplied.rivenbymultimediabasedapplications,anticipatedAsinmanyothercoherentdigitalwirelessreceivers,chan-futurewirelesssystemswillrequirehighdataratenelestimationisalsoanintegralpartofthereceiverdesignsDcapabletechnologies.NoveltechniquessuchasincoherentMIMO-

6、OFDMsystems[13].Inwirelesssystems,OFDMandMIMOstandaspromisingchoicesforfuturehightransmittedinformationreachestoreceiversafterpassingdataratesystems[1,2].througharadiochannel.Forconventionalcoherentreceivers,OFDMdividestheavailablespectrumintoanumberoftheeffectofthechannelonthetransmittedsign

7、almustbeoverlappingbutorthogonalnarrowbandsubchannels,andestimatedtorecoverthetransmittedinformation[14].Aslonghenceconvertsafrequencyselectivechannelintoanon-asthereceiveraccuratelyestimateshowthechannelmodifiesfrequencyselectivechannel[3].M