高速移动环境下的MISO多普勒频移估计分析

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1、AbstractAbstractInrecentyears,withtherapiddevelopmentofwirelesscommunicationtechnology,OrthogonalFrequencyDivisionMultiplexing(OFDM)technologyhasbeenadoptedbymanywirelesscommunicationstandards.OFDMtechnologyhasattractedsomuchattention,thatisbecauseithasremarkableadvantages,suchashigherspectrumeffic

2、iency,effectivelyagainstmultipathfadingandsoon.AlthoughOFDMhassomanyadvantages,theOFDMsystemisverysensitivetofrequencyoffset,especiallyinhigh-mobilityenvironment.HighmobilitybetweenthetransmitterandreceivercangeneratehighDopplerfrequencyshiftwhichwilldestroytheorthogonalitybetweensubcarriersofOFDMs

3、ystems,causeinter-carrierinterference(ICI)andreducetheperformanceofOFDMsystem.Therefore,thestudyofDopplerfrequencyshiftinhigh-speedmobileenvironmenthasimportanttheoreticalandpracticalvaluetoimprovetheperformanceofthecommunicationsystem.ThisarticlefocusesonMISO-OFDMDopplershiftestimationandDopplersh

4、iftcompensationalgorithmsinhigh-speedmobileenvironment.Themainresearchworksandcontributionsarelistedasfollows:i)Dopplerfrequencyshiftestimationalgorithmbasedoncyclicprefixinhigh-speedmobileenvironment.WeassumethattheOFDMsystemshasreachedsynchronizationandsignaltonoiseratio(SNR)isknownatthereceiver,

5、WeusecyclicprefixwhichisthetailpartoftheOFDMsymbolsasguardinterval,Theautocorrelationfunctionofcyclicprefixcanbecalculated,andaccordingtotherelationshipbetweentheautocorrelationfunctionofcyclicprefixandzero-orderBesselfunctionofthefirstkind,wecanestimatethemaximumDopplerfrequencyshift.Thereisacerta

6、indeviationbetweenestimatedDopplerfrequencyshiftandtheactualDopplerfrequencyshift,andthenthepolynomialfittingmethodcancorrectestimatederrortogetmoreaccurateDopplerfrequencyshift.SimulationresultsdemonstratetheaccuracyofDopplershiftestimation.ii)Dopplerfrequencyshiftcompensationalgorithmbasedonthedi

7、rectionofarriver(DOA)estimatedwithEigenspaceinhigh-speedmobileenvironment,weconsidertheaeronauticalcommunications.Firstlyweanalyzeaeronauticalcommunicationsystemmodelandprocessthereceivedsignal,theDOAsofdif