简介:由于MIMO雷达发射相互正交的波形,因此正交波形设计是MIMO雷达实现的关键问题。针对MIMO雷达发射波形正交的特点,介绍了正交频分复用线性调频波形(OFDM—LFM)的设计原理。提出了一种正交频分线性调频波形产生的实现方案,该方案通过并行发射多路频分的线性调频信号形成OFDM—LFM波形。设计了一种由主控计算机、波形控制模块和数字中频合成模块构成的OFDM—LFM波形产生器。给出了基于AD9910数字斜坡调制方式产生单通道线性调频信号的方法和0sK功能产生多通道线性调频脉冲信号的方法,并对单通道线性调频信号线性度进行了分析。最后给出了其中两通道LFM信号频谱和一通道线性调频脉冲信号的时域波形的测试结果,验证了方案的正确性和可行性。
简介:MIM0雷达是一种全新体制的雷达技术,在其接收端利用发射端全向发射正交信号的原理,通过匹配滤波技术恢复每个发射信号分量,确保信号之间保持良好的正交性是MIMO雷达实现的关键。首先给出了相参MIM0雷达的信号模型;然后分析了正交频分线性调频信号的互模糊函数,并对互相关峰值电平出现的位置和幅度进行了分析,推导出了MIM0雷达相邻发射信号之间频率间隔所需满足的条件和相参MIM0雷达匹配滤波技术的数学模型;最后通过仿真实验证明了理论分析的正确性,而且仿真实验还表明:在正确设计MIM0雷达发射信号的条件下,噪声电平对匹配滤波技术的影响远大于自相关旁瓣电平和互相关峰值。
简介:Large-scaleMIMO(multiple-inputmultiple-output)systemswithnumerouslow-powerantennascanprovidebetterperformanceintermsofspectrumefficiency,powersavingandlinkreliabilitythanconventionalMIMO.Forlarge-scaleMIMO,thereareseveraltechnicalissuesthatneedtobepracticallyaddressed(e.g.,pilotpatterndesignandlow-powertransmissiondesign)andtheoreticallyaddressed(e.g.,capacitybound,channelestimation,andpowerallocationstrategies).Inthispaper,weanalyzethesumrateupperboundoflarge-scaleMIMO,investigateitskeytechnologiesincludingchannelestimation,downlinkprecoding,anduplinkdetection.Wealsopresentsomeperspectivesconcerningnewchannelmodelingapproaches,advanceduserschedulingalgorithms,etc.
简介:Theresearchandapplicationofwirelesslocalareanetworks(WLAN)technologyareinastageofrapiddevelopment.Ithasbeenoneofresearchfocusesofthewirelesscommunicationsfield.Throughtheuseofenhancedsingle-user(SU)/multi-user(MU)multipleinputmultipleoutput(MIMO)-orthogonalfrequencydivisionmultiplexing(OFDM)technology,thenextgenerationWLANIEEE802.11acdramaticallyincreasesthethroughput.AnimprovedMIMO-OFDMschemebasedonmodulationdiversityisproposedforthenextgenerationWLAN.Itusestwo-dimensionalmodulationdiversitytothecurrentIEEE802.11actransmissionscheme.Throughthespace-time-frequencycomponentinterleaverandtherotationalmodulation,theproposedschemeexhibitshighspectralefficiencyandlowerrorrateinfadingchannels.ThesimulationresultsshowthattheproposedschemesignificantlyoutperformstheSU/MUMIMO-OFDMschemeinthecurrentIEEE802.11acstandard,whichisupto5dB.
简介:Thispaperdiscussestheproblemofdirectionofdeparture(DOD)anddirectionofarrival(DOA)estimationforabistaticmultipleinputmultipleoutput(MIMO)radar,andproposesanimprovedreduced-dimensionCaponalgorithmtherein.Comparedwiththereduced-dimensionCaponalgorithmwhichrequirespairmatchingbetweenthetwo-dimensionalangleestimation,theproposedalgorithmcanobtainautomaticallypairedDODandDOAestimationwithoutdebasingtheperformanceofangleestimationinbistaticMIMOradar.Furthermore,theproposedalgorithmhasalowercomplexitythanthereduced-dimensionCaponalgorithm,anditissuitablefornon-uniformlineararrays.ThecomplexityoftheproposedalgorithmisanalyzedandtheCramer-Raobound(CRB)isalsoderived.Simulationresultsverifytheusefulnessoftheproposedalgorithm.
简介:与增加的精力消费,精力效率(EE)作为光谱效率(SE)为无线通讯网络被看作了一个重要度量标准。在这份报纸,为downlink多用户的EE优化问题多重输入多重产量(MU-MIMO)有巨大的天线的系统被调查。根据凸的优化理论,在那里存在完成最佳的EE的唯一的全球性最佳的电源分配,并且仅仅与隧道状态信息有关的最佳的EE靠近形式被导出经分解。然后,两个都,有不同复杂性的近似、精确的电源分配算法被建议完成最佳的EE。近似算法获得的最佳的EE与一致到在可控制的错误限制以内由精确算法完成了那的模拟结果表演,和这些建议算法比存在相等的电源分配算法更好表现。有在底的天线的数字的最佳的EE和相应SE增加驻扎无线通讯网络,它为下一代是有希望的。
简介:Themodeswitchingbetweenspatialmultiplexing(SM)andspace-timeblockcode(STBC)diversityisinvestigatedforthemultiple-inputmultiple-output(MIMO)automaticrepeatrequest(ARQ)system.Fiveimportantpracticalfactorsareconsideredintheproposedswitchingscheme:transmitcorrelation,ARQtechnique,packetlossprobability(PLP)constraint,discreteratetransmission(DRT)andchannelcoding.Underthespatiallycorrelatedchannel,thedistributionsofthepostsignal-to-interference-plusnoiseratio(SINR)fortheSMmodeandtheSTBCmodeareobtainedbyusingGammaapproximations.Thenthispaperderivestheclosed-formexpressionsofthePLPandthethroughputfordifferentmodeswhentheARQtechniqueisemployed,basedonwhichthemodeswitchingalgorithmisproposedtoimprovethespectralefficency.Inthesimulation,thecorrectionoftheexpressionsisfirstverified.Then,thesignificantgainobservedbytheproposedalgorithmispresented.Sincetheswitchingpointisthekeyparametertoimplementthemodeswitching,thispaperalsoshowshowtheswitchingpointisaffectedbythepracticalfactorsconsidered.
简介:研究了基于空间信道模型(SCM)的空域相关矩阵,搭建了MIMO通信信道仿真平台,同时考虑时延扩散、多普勒效应、波达方向及角度扩散等多种信道参数,通过蒙特卡罗方法计算了MI-MO系统的信道容量、空时相关性、衰落特性及功率延迟分布特性。指出了在信道的去极化作用下,无线通信系统的多径衰落可以采用极化分集和天线分集等技术进行克服,平均入射角对系统性能起着关键的作用。
简介:Abi-caponbeamforming(BCB)algorithmformulti-inputmulti-output(MIMO)radarisdevelopedonthebasisofcorrelationdomain.Byvectorizingtheechomatrixanditstranspose,theconventionalcaponcostfunctionistransformedintobi-caponquadraticfunctions.Bycalculatingtwolowerdimensionalweightvectorswithsub-matricesofthecorrelationmatrix,BCBcansignificantlydecreasethecomputationalcomplexityandtherequirementoftrainingsamples.Inthepresenceofshortdatarecords,BCBcanachievebetterinterferencesuppressionperformancethanfullyadaptivecaponalgorithm.Simulationresultsarepresentedtodemonstratetheeffectivenessoftheproposedmethod.
简介:Tomaximizethethroughputoffrequency-selectivemulticastchannel,theminimum-phaseFiniteImpulseResponse(FIR)precoderdesignisinvestigatedinthispaper.Thisproblemcanbesolvedintwosteps.Firstly,wefocusondesigninganonminimum-phaseFIRprecoderunderthecriterionofmaximizingthethroughput,anddeveloptwoefficientalgorithmsfortheFIRprecoderdesignfromperspectivesoffrequencydomainandtimedomain.Inthesecondstep,basedonthetheoryofspectralfactorization,thenonminimum-phaseFIRprecoderistransformedintothecorrespondingminimum-phaseFIRprecoderbyaclassiciterativealgorithmwithoutaffectingthethroughput.Numericalresultsindicatethattheachievablerateoftheproposeddesignhasremarkableimprovementoverthatofexistingschemes,moreover,thegroupdelayintroducedbytheFIRprecoderisminimized.