新型变步长LMS方法及OFDMA信号DOA估计中的应用(英文)-豆柴文库

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新型变步长LMS方法及OFDMA信号DOA估计中的应用(英文)
Introduction
Therapidlyincreasingdemandforhigh-speedcommunicationinwirelessnetworkshasledtotheintegrationofvariousadvancedtechnologies.Orthogonalfrequencydivisionmultipleaccess(OFDMA)isoneofthemostpopulartechnologiesusedinmodernwirelesscommunicationsystems,whichsupportshigherdataratesandimprovedspectralefficiency.However,accurateestimationofthedirectionofarrival(DOA)oftheOFDMAsignalsisessentialforefficientsignaldetectionandinterferencecancellation.Theconventionalleast-mean-square(LMS)algorithmiscommonlyusedforDOAestimation,butitsuffersfromslowconvergenceandhighcomputationalcomplexity.Recently,anewtypeofvariablestep-sizeLMSalgorithmhasbeenproposed,whichcanimprovetheperformanceofDOAestimationinOFDMAsystems.Thispaperprovidesadetailedoverviewofthenewvariablestep-sizeLMSalgorithmanditsapplicationinOFDMAsignalDOAestimation.
VariableStep-SizeLMSAlgorithm
Thevariablestep-sizeLMS(VSS-LMS)algorithmisanadaptivefilteringalgorithmthatisusedforsignalprocessingandDOAestimationinwirelesscommunicationsystems.ThisalgorithmisanimprovementoverthetraditionalLMSalgorithm,whichisbasedonaconstantstep-size.TheVSS-LMSalgorithmvariesthestep-sizetoachievebetterconvergencespeed,robustness,andsteady-stateperformance.Thealgorithmupdatesthecoefficientsoftheadaptivefilterbyminimizingthemean-squareerrorbetweenthedesiredsignalandtheestimatedsignal.TheVSS-LMSalgorithmadjuststhestep-sizebasedonthemean-squaredvalueoftheinputsignaltotheadaptivefilter.Thestep-sizeisincreasedwhenthesignalpowerislowanddecreasedwhenthesignalpowerishigh,whichresultsinfasterconvergenceandreducedsteady-stateerror.
TheVSS-LMSalgorithmhasseveraladvantagesoverthetraditionalLMSalgorithm.Firstly,itcanachievefasterconvergencespeedthanthetraditionalalgorithm,whichisparticularlyusefulinreal-timesignalprocessingapplications.Secondly,theadaptivenatureofthestep-sizemakesitlesssensitivetovariationsininputsignals,makingitmorerobusttonoiseandinterference.Thirdly,theVSS-LMSalgorithmrequiresfewercomputationalres