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2004-06-01231200611006-9348200601-0294-05100037SYSTEMVIEWLMSMATLABLMS/TN914.42ASuppressionTechniquesagainstNarrow-BandInterferenceinDS/SSCommunicationsSystemWANGXing-shengCHENYanSchoolofInformationEngineeringBeijingTechnologyandBusinessUniv.Beijing100037ChinaABSTRACTThispaperfirstintroducesamodelofSpread-Spectrumcommunicationssystemthenappliesthesoft-wareSYSTEMVIEWtothesystemsimulationanditgetstorealizethatthesystemownsapowerfulanti-interferencepropertybyitself.Itcomparestheoutputsignalsofreceiverswithdifferentaddresscodesandindicatesthatthesystemcansuppressinterferencecausedbymultipleaccess.Becauseoflimitedbandwidthonlyrelyingonitsspread-spectrumgainisnotenoughthereforeitisessentialtoaddanadaptivefilterbeforedespreading.Thepapertesti-fiestheavailabilityofsuppressionagainstnarrow-bandinterferenceandanalyzestheLMSalgorithm.Atlastitsim-ulatesthewholecourseoffilteringwithMATLAB.TheconclusionisthatapplicationofadaptivefilterbasedonLMSalgorithmcandecreaseBitErrorRateneartozeroandsuppressamajorityofenergyofjammer.KEYWORDSDS/SSNarrow-bandinterferenceLMSBiterrorrateEnergysuppression1602PNBPSKDS/BPSK1SYSTEMVIEWBPSK224921DS/BPSK3PNPN2334Xˆixn=sn+jnun0σ2jnen=xn-Σmi=1wixn-i=sn-Σmi=1wisn-i+jn-Σmi=1wijn-ien=esn+ejnE|esn|2|esn|2=s2n-2snΣmi=1wisn-i+Σmi=1wisn-i2=s2n+Σmi=1j=i+1wiwjsn-isn-j+Σmi=1w2is2n-5924i-2snΣmi=1wisn-iE|esn|2=1+Σmi=1w2iσ25E|esn|2WsnjnWesn4LMSLMSLMSJw=|en|2Jw=E|en|24W=w1w2wmTXΔ=Xn-1Xn-1Xn-mTXˆnenen=Xn-Xˆn=Xn-XTΔWng=?Jw=6e2n6Wn=6e2n6w1n6e2n6w2n6e2n6wmn[]T=2en6en6Wn=-2enXΔwn+1=wn-12µgnLMSwn+1=wn+µenXΔ0µ1λmax2mSmaxλmaxmSmax5MATLAB400DFT±15.1LMS5DFT5.262π/2.9DFTLMS769267135%01µBERBER1.41420.0080.24502.00.0080.327502.44950.0080.36502.82840.0080.39503.16230.0080.39503.46410.0080.3950jammerenergy-suppressionratio8µ5.3LMS890esn9/6/LMS30%070%-80%90%/1.M.1993.2MarvinKSimone.t.SPREADSPECTRUMCommunica-tionsHandbookM.2002.3..792M.PrenticeHallPublishingHouseofElectronicsIndustry2003.4BernardSklar.DigitalCommunicationsFundamentalsandApplications.PHPTRM.PublishingHouseofElectronicsIn-dustry2002.5.5M.2001.6.M.2000.7.M.2000.8.MATLAB6.5M.2003.9.M.2003.1980-001963-～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～2696125k125K*3.43469/4K=107.34msLinearProfiling7C7VisualDSP++56161PPVaidyanathan.MultirateDigitalFiltersFilterBanksPoly-phaseNetworksandApplicationsATutorialC.Proc.ofIEEEJanuary199078155-93.2RAnsariandBLiu.MultirateSignalProcessingCh.14ofMitraSK.andKaiserJfEditorsHandbookforDigitalSignalProcessingM.NewYorkJoneWiley&Sons1993.3DRZahirniakDLSharpinTWFields.AHardware-efficientMultimateDigitalChannelizedReceiverArchitectureJ.IEEETransonAes1998341137-151.4.J.20013255-260.5.DSPJ.20033-454-62.6JamesTsui..M.2002.7.M.2001.8.DSPM.2002.1977-DSP1969-1943-892