DS-CDMA系统中基于GSC算法的盲空时多用户检测-豆柴文库

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DS-CDMA系统中基于GSC算法的盲空时多用户检测
1.Introduction
Direct-sequencecode-divisionmultipleaccess(DS-CDMA)isawidelyusedmultipleaccesstechnologyinwirelesscommunicationsystems.OneofthemainchallengesinDS-CDMAsystemsismulti-userdetection(MUD),whichisusedtoseparatesignalsfrommultipleusersreceivedbyasingleantenna.BlindMUDisatechniqueusedwhenthechannelinformationisunknown.Generalizedsidelobecanceller(GSC)isoneofthepopularalgorithmsforblindMUDinDS-CDMAsystems.Thispaperprovidesanin-depthanalysisoftheGSCalgorithm-basedblindMUDforDS-CDMAsystems.
2.Background
InDS-CDMAsystems,multipleuserssharethesamefrequencybandbyutilizingdifferentspreadingcodes.ThereceiverreceivesthesuperimposedsignalsfrommultipleusersandseparatesthembyusingMUDtechniques.InconventionalMUD,thechannelinformationisknown.However,inpracticalsystems,thechannelinformationisoftenunknown,andtheblindMUDisused.BlindMUDcanbecategorizedintotwotypes:non-data-aidedanddata-aided.Non-data-aidedblindMUDdoesnotrequireanyknowledgeofthetransmitteddata.Ontheotherhand,data-aidedblindMUDusesthetransmitteddataforchannelestimation.
TheGSCalgorithmisapopularmethodfornon-data-aidedblindMUDinDS-CDMAsystems.TheGSCalgorithmcanbeusedtocanceltheinterferencebyusingafiltercalledtheweightvector.Theweightvectorisadaptivelyupdatedusingtheinterferenceestimationobtainedfromthesignalsreceivedfromotherusers.TheGSCalgorithmcancanceltheinterferencecausedbythesidelobesofthespreadingcodesandothersourcessuchasnoiseandmultipath.
3.GeneralizedSidelobeCanceller(GSC)
TheGSCalgorithmusesaconfigurationthatincludesamainfilterandanadaptivefilter.Themainfilterisdesignedtoextractthedesiredsignalwhilesuppressingtheinterference,andtheadaptivefilterestimatestheinterferenceandsubtractsitfromthereceivedsignal.
Themainfilterisafixedfilterdesignedtohavebetterchannelselectivitythanthespreadingcodesusedbythemultipleusers.Themainfilterisdesignedsothatitsresponsetothedesiredsignalismaximized,anditsresponsetotheinterferenceisminimized.Themainfilterisusedtoextractthedesiredsignalfromtherec