简介:CapacityofMIMOLAS-CDMAsystemsundermulti-pathfadingchannelswithtwodifferentcorrelatingmodelswerestudiedinthepaper.Influencesofthetwomodelsparametersoncapacitywereanalyzed.Thenumericalresultspresentthat:accordingtotheVariousScatteringEnvironmentscorrelatingmodel,whentheinner-elementsdistanceofantennasarrayislargethan0.5λ,correlationalmostdoesnottakefromthesystemcapacity;fortheSalz-Wintercorrelatingmodel,thespreadangleatreceiveristheotherkeyfactor,italsoinfluencethesystemcapacitygreatly.
简介:Thisarticleproposesatime/frequencysynchronizationalgorithminthemultipleinputmultipleoutput(MIMO)systems,inwhichtheperfectcompletegeneralizedcomplementaryorthogonallooselysynchronouscodegroupsareusedasthesynchronizationsequence.Thesynchronizationalgorithmisdividedintofourstages:1)synchronizationintimedomainbysignalautocorrelation;2)synchronizationinfrequencydomainbyfastFouriertransform(FFT);3)multipathdissociationusingcoherentdetectionandfinetimesynchronization;4)finefrequencyoffsetestimationbyphaserotation.Aspertheperfectcompletegeneralizedcomplementaryorthogonallooselysynchronouscodegroups,thecross-correlationandout-of-phaseauto-correlationforanyrelativeshiftbetweenanytwocodesisalwayszero.Thisidealpropertymakesthetime/frequencysynchronizationalgorithmsimpleandefficient.Thesimulationresultsshowthateveninthemultipathfastfadingchannelwithlowsignalnoiseratio(SNR),theMIMOsystemcangetsynchronizedbothinthetimedomainandfrequencydomainwithhighstabilityandreliability.
简介:新涡轮反复的接收装置结构为uplink被建议多重输入的多重产量的直角的频率分割多重存取(MIMO-OFDMA)系统。轮流出现空间的概括期望最大化(半自动地面防空系统)算法自然地在反复的接收装置的框架被嵌入用涡轮察觉者产量执行同步和察觉。在每次重复,期望步打算移开多重存取另外的异步的用户引起的干扰(MAI),和最大化步被利用估计要求的参数(即,预定偏移量,搬运人频率偏移量,隧道状态信息,等等)顺序为每个用户。模拟结果证明建议算法能仔细接近理想的接收装置的表演,当处理复杂性比常规察觉者相当低时。
简介:Multi-cellmulti-usermultiple-inputmultiple-output(MC-MU-MIMO)isapromisingtechniquetoeliminateinter-userinterferenceandinter-cellcochannelinterferenceinwirelesstelecommunicationsystems.AsthelargenumberofusersinthesystemandthelimitednumberofsimultaneouslysupportableuserswithMC-MU-MIMO,itisnecessarytoselectasubsetofuserstomaximizethetotalthroughput.However,thefullycentralizeduserselectionalgorithmsusedinsinglecellsystem,whichwillincurhighcomplexityandbackhaulloadinmulti-cellcooperativeprocessing(MCP)systems,arenotsuitabletoMC-MU-MIMOsystems.ThisarticlepresentsatwocascadeduserselectionmethodforMCPsystemswithmulti-cellblockdiagonalization.Inthispaper,alocaloptimalsubsetofusers,whichcanmaximizethelocalsumcapacity,isfirstchosenbythegreedymethodineverycooperativebasestationinparallel.Then,allthecooperativebasestationsreporttheirlocaloptimaluserstothecentralunit(CU).Finally,theglobaloptimalusers,whichcanmaximizetheglobalsumcapacityofMCPsystems,areselectedfromtheaggregatedlocaloptimalusersattheCU.Thesimulationresultsshowthattheproposedmethodperformscloselytotheoptimalandcentralizedalgorithm.Meanwhile,thecomplexityandbackhaulloadarereduceddramatically.
简介:Tomaximizethethroughputoffrequency-selectivemulticastchannel,theminimum-phaseFiniteImpulseResponse(FIR)precoderdesignisinvestigatedinthispaper.Thisproblemcanbesolvedintwosteps.Firstly,wefocusondesigninganonminimum-phaseFIRprecoderunderthecriterionofmaximizingthethroughput,anddeveloptwoefficientalgorithmsfortheFIRprecoderdesignfromperspectivesoffrequencydomainandtimedomain.Inthesecondstep,basedonthetheoryofspectralfactorization,thenonminimum-phaseFIRprecoderistransformedintothecorrespondingminimum-phaseFIRprecoderbyaclassiciterativealgorithmwithoutaffectingthethroughput.Numericalresultsindicatethattheachievablerateoftheproposeddesignhasremarkableimprovementoverthatofexistingschemes,moreover,thegroupdelayintroducedbytheFIRprecoderisminimized.
简介:Inthisarticle,resultsobtainedfromwidebandmultiple-inputmultiple-outputchannelmeasurementsat4.9GHzarepresented.Measurementswereperformedinanindoorhotspotscenariowithbothline-of-sightandnon-line-of-sightpropagationconditions.Verticalpolarizeduniformlineararrays(ULAs)withdifferentantennaspacingandorientationwereutilizedforinvestigatingtheimpactofantennaconfigurationsonthesystemperformance.Basedonmeasuredchannelimpulseresponses,thespatialcorrelationofULAisanalyzedandcomparedwiththetheoreticalvaluescalculatedfromthepowerazimuthspectrum.Followingthat,theeigenvaluestatisticsandcapacitywithrespecttoantennaspacingandorientationaregivenandcompared.Thediversity-multiplexingtradeoff(DMT)ofmeasuredchannelsatoperationalsignal-to-noiseratio(SNR)isalsopresented.ThereasonwhytheDMTofmeasuredchannelsismuchlowerthanthatofi.i.d.Rayleighchannelsisspecified.
简介:摘要:大规模多输入多输出(MIMO)天线阵列作为第五代(5G)及更高级别移动通信系统的关键技术之一,是当前时代研究的主要课题,这需要在实际实施中克服重大挑战。在本文中,我们分别讨论了5G背景下大规模MIMIO技术的发展方向、面临的挑战以及重点应用领域。
简介:摘要:本文是研制开发了一种应用于5G通信中的MIMO天线用板间连接器。实现DC-6GHz内射频信号传输。是在常规板间连接器的基础上,通过结构设计降低了产品的互调影响,实现了板与板之间连接器的低互调、高性能。主要应用于5G通信中的天线模块,具有附加值高,性能优越等特点,其优越的互调指标具有传统的板间连接器无法比拟的技术优势。
简介:《蝙蝠和雷达》是一篇知识性和逻辑性较强的儿童科学文艺作品。教学时,根据科学文艺作品的特点及本文的叙述特点,可用以下几种方法组织教学。一、运用"题读法"了解课文大意学习迁移规律表明:学生已经学得的东西在新情境中会产生有利的影响。教学时在学生充分预习课文的基础上,教师可先让学生回忆刚学过的《列宁和卫兵》,课题和课文内容的关系,然后比较《蝙蝠和雷达》,使学生大致了解本文是写蝙蝠和雷达这两种东西,雷达的研制是从蝙蝠身上得到的启示。二、运用"提问法"突出文章的重难点教学时单刀直入地提出:课文里提出两个什么问题?(为什么编蝠无论怎样飞也不会撞上什么东西?飞机在夜里能安全飞行是怎样从蝙蝠身上得到启示的?)其次,引导学生理解文章是怎样研究问题的(由试验得出蝙蝠是凭借嘴和耳朵探路飞行的)。再次,引导学生理解文章是怎祥解决问题的(雷达是
简介:摘 要:本文主要介绍了某型号气象雷达开机后出现“雷达通电后不工作,无自检画面”的故障现象,出现故障现象后,操作人员对雷达多次进行通电、断电操作,雷达均不能正常工作,切换到自检模式,综显系统无自检画面显示。