Sparse Channel Estimation for Multicarrier

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1、IEEETRANSACTIONSONSIGNALPROCESSING(ACCEPTED)1SparseChannelEstimationforMulticarrierUnderwaterAcousticCommunication:FromSubspaceMethodstoCompressedSensingChristianR.Berger,Member,IEEE,ShengliZhou,Member,IEEE,JamesC.Preisig,Member,IEEE,andPeterWillett,

2、Fellow,IEEEAbstract—Inthispaper,weinvestigatevariouschannelesti-platformandsea-surfacemotion[5].Thelongchannelde-matorsthatexploitchannelsparsityinthetimeand/orDopplerlayspreadleadstosignificantinter-symbol-interference(ISI)domainforamulticarrierunder

3、wateracousticsystem.Weuseainsingle-carriertransmissions[6].Thereceivercomplexitypath-basedchannelmodel,wherethechannelisdescribedbyaforchannelequalizationbecomesamajorburdenwhenthelimitednumberofpaths,eachcharacterizedbyadelay,Dopplerscale,andattenua

4、tionfactor,andderivetheexactinter-carrier-symbolrateincreases.Multicarrierapproacheslikeorthogonalinterference(ICI)pattern.ForchannelsthathavelimitedDopplerfrequencydivisionmultiplexing(OFDM)canequalizethespreadweshowthatsubspacealgorithmsfromthearra

5、yprocess-channelatlowcomplexity,buttheaforementionedDoppleringliterature,namelyRoot-MUSICandESPRIT,canbeappliedeffectsdestroytheorthogonalityofthesub-carriersandleadforchannelestimation.ForchannelswithDopplerspread,wetointer-carrier-interference(ICI)

6、.adoptacompressedsensingapproach,informofOrthogonalMatchingPursuit(OMP)andBasisPursuit(BP)algorithms,andThecombinationoflargedelayspreadandsignificantutilizeovercompletedictionarieswithanincreasedpathdelayDopplereffectsqualifyUWAchannelsasdoubly(time-

7、andresolution.Numericalsimulationandexperimentaldataofanfrequency-)spreadchannels.OneknownapproachtothisclassOFDMblock-by-blockreceiverareusedtoevaluatetheproposedofchannelsistheuseofabasisexpansionmodel(BEM)algorithmsincomparisontotheconventionallea

8、st-squares(LS)toreflectthetime-varyingnatureoftheUWAchannel,seechannelestimator.WeobservethatsubspacemethodscantoleratesmalltomoderateDopplereffects,andoutperformtheLSe.g.,[7]–[9].Eventhoughthetime-varyingnatureofchannelsapproachwhenthechannelisindeed