直接序列扩频通信系统抗干扰技术研究

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1、分类号UDC工学博士学位论文直接序列扩频通信系统抗干扰技术研究博士生姓名韭查连国防科学技术大学研究生院二oo六年三月国防科学技术大学研究生院学位论文ABSTRACTDirectsequencespreadspectrum①SSS)communicationsystemshavemanyadvantages，includinglowprobabilityofintercept(LPI)transmission，multipleaccessing，multipathsuppressionandnarrowbandinterferencesuppression．Ithasbeenwide

2、lyusedinpersonalcommunicationnetwork(PeN)，wirelessLAN(WEAN)，3Gmobilecommunicationandmilitarytacticalcommunication．AsiSwellknown，theinherentprocessinggainofspreadspectrumsystemswill，inmanycases，providethesystemwithinterferencere{eetioncapabili衅．BmifthelevelofinterferenceiStoohigh，theinterferenc

3、eimmunityearlbeimprovedsignificantlybyusingsignalprocessingtechniquesthatcomplementthespreadspectrummodulation．TheresearchofthisdissertationiSbasedonthedemandsofDSSSnarrowbandinterferencesuppressionintermediatefrequencydigitalizedreceiver．Asimplifiedsignalmodelofdig!italizedreceiverandthesigna

4、lmodelofinterference。suchastoneintcrference，autoregressiveinterferenceanddigitalinterference，areprovided．AnditisanalyzedindetailthecapabilityofDSSScommunicationsystemsinsuppressingbroadbandGanssianinterference．singletoneinterferenceandpartialbandinterference．Differenttimedomaininterferencesupp

5、ressiontechniques‘callbeestablishedfordifferentinterferencemodels．Firstly，theperformancesoflinearandnonlinearalgorithmsbasedoninterferenceestimator／subtracterarecompared．Secondly，anovelinterferencesuppressionalgorithrnbasedonsubspacctrackingisproposedfor111etoneinterferencemodel．Finally．the—st

6、abilityperformance．of‘the—transformdomain—normalizedleastmeansquare(TDNLMS)adaptivelyimplementingstru．ctureofminimumbiterrorratio(MBER)receiverisanalyzed．Filterbankisthemultiratesignalprocessingstructure，whichdecomposesadigitalsignalintoabankoffrequencybands．nediscreteFouriertransform(DFT)，lap

7、pedorthogonaltransfonn(L01)andcosinemodulatedfilterbanks(CMFB)areallspecialcasesofthisgeneralstructure．Firstly，thesignal—to·noiseratiodegradationofwindoweddiscreteFouriertransform(WDFT)isstudiedandtheimprovedmethods．n锄elyoverlap—addando