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1、第39卷第3期东南大学学报(自然科学版)Vol39No32009年5月JOURNALOFSOUTHEASTUNIVERSITY(NaturalScienceEdition)May2009doi:10.3969/.jissn.1001-0505.2009.03.001基于FRESH滤波器的DSSS系统窄带干扰抑制技术1,211魏安全沈连丰宋铁成(1东南大学移动通信国家重点实验室,南京210096)2(解放军理工大学通信工程学院,南京210007)摘要:为了减小基于时域线性预测干扰估计的DSSS系统窄带干扰抑制技术对有用信号产生的损伤,根据
2、干扰环境下接收信号的循环平稳特性,提出了一种利用频移滤波器对干扰进行估计并将干扰抵消的DSSS系统窄带干扰抑制方法.该方法在对干扰进行估计时,既利用了干扰的时域相关性,又利用了干扰的频域相关性.理论分析和仿真结果表明,在强干扰环境下,接收信号的循环平稳性主要由强干扰决定.与传统时域线性预测方法相比,该方法对干扰估计的时平均均方误差更小,能够更精确地估计和消除频谱相关的干扰,减轻对有用信号的损伤,进一步降低系统的误比特率,因而具有更加优良的干扰抑制性能,特别在干扰较强或干扰频带较宽时,优势更加明显.关键词:循环平稳;频移滤波器;直接序列扩频;干扰抑制中图分类号:
3、TN9117文献标志码:A文章编号:1001-0505(2009)03041907NBIsuppressiontechniqueofDSSSsystemsbasedonFRESHfilter1,211WeiAnquanShenLianfengSongTiecheng(1NationalMobileCommunicationsResearchLaboratory,SoutheastUniversity,Nanjing210096,China)(2InstituteofCommunicationsEngineering,PLAUniversity
4、ofScienceandTechnology,Nanjing210007,China)Abstract:Tomitigatetheimpairmenttothedesiredsignalcausedbytheconventionalnarrowbandinterference(NBI)suppressiontechniquebasedoninterferenceestimationsbylinearpredictionsintimedomainindirectsequencespreadspectrum(DSSS)systems,anapproachofsu
5、ppressingNBIinDSSSsystemsusingafrequencyshift(FRESH)filtertoestimatetheNBIisproposedbasedonthecyclostationarycharacteristicsofthereceivedsignalintheenvironmentoftheinterference,whichcanusethecorrelationoftheinterferencenotonlyintimedomainbutalsoinfrequencydomainfortheinterferencees
6、timation.Theresultsfromtheoreticalanalysisandsimulationsindicatethatthecyclostationarycharacteristicsofthestronginterferenceinthereceivedsignalisexhibitedmainlyintheenvironmentofthestronginterference.Comparedwiththetraditionaltechniquesbasedonlinearpredictionsintimedomain,smallert
7、imeaveragemeansquareerrorscanbeachieved,thespectrumcorrelatedinterferencecanbeestimatedandeliminatedmoreexactly,andtheimpairmenttothedesiredsignalismitigated.Thebiterrorrateofthesystemisreducedfurther,sobetterinterferencesuppressionperformancecanbeachieved.Theadvantageismoreevid
8、entespeciallywhenth
