CDMA卫星移动通信系统中的盲干扰抑制新方法-豆柴文库

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CDMA卫星移动通信系统中的盲干扰抑制新方法
CDMA(CodeDivisionMultipleAccess)technologyiswidelyusedinsatellitemobilecommunicationsystems,andithastheadvantagesofanti-interferenceandhighsecurity.However,inpracticalsatellitecommunicationsystems,theexistenceofblindinterferencecanseriouslyaffecttheperformanceofCDMAsystems.Therefore,itisessentialtosuppressblindinterferenceinCDMAsatellitemobilecommunicationsystems.
Inthispaper,weproposeanewmethodforblindinterferencesuppressioninCDMAsatellitemobilecommunicationsystems.Theproposedmethodconsistsofthreesteps:blindinterferenceestimation,adaptivefiltering,andinterferencesuppression.Thedetailofeachstepisasfollows.
Step1:BlindInterferenceEstimation
Thefirststepistoestimatetheblindinterferencebasedonthereceivedsignals.Theblindinterferenceiscausedbymulti-pathpropagation,atmosphericturbulence,andotherfactors.Toestimatetheblindinterference,weusetheclassicalblindsourceseparationalgorithmcalledIndependentComponentAnalysis(ICA).ICAisastatisticaltechniquethatseparatesasetofmixedsignalsintoindependentsignals.Inthiscontext,weassumethatthereceivedsignalisalinearmixtureofthedesiredsignal,theblindinterference,andadditivenoise.WeapplyICAtothemixedsignalstoseparateouttheindependentcomponentsthatcorrespondtothedesiredsignalandtheblindinterference.Theestimatedblindinterferenceisthensubtractedfromthereceivedsignaltoremovetheblindinterference.
Step2:AdaptiveFiltering
Thesecondstepistoperformadaptivefilteringtofurthersuppresstheresidualinterferencethatisnotremovedbytheblindinterferenceestimation.Adaptivefilteringisapowerfulsignalprocessingtechniquethatcanefficientlyestimatethelinearfiltercoefficientsbasedonthereceivedsignals.Toperformadaptivefiltering,weusetheLeastMeanSquare(LMS)algorithmwhichisawell-knownadaptivealgorithm.NotethattheLMSalgorithmrequiresareferencesignal,whichisoftenassumedtobethedesiredsignal.However,insatellitemobilecommunicationsystems,thereferencesignalisnotavailable.Therefore,weproposetousetheestimatedblindinterferenceasthereferencesignalforadaptivefi