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ID:34079785
大小:2.69 MB
页数:74页
时间:2019-03-03
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1、哈尔滨工程大学硕士学位论文ResearchonSynchronizationforOFDMSystem姓名:FellouhSfiane[思凡]申请学位级别:硕士专业:信号与信息处理指导教师:Prof.MaHuiZhu[马惠珠]201103ResearchOilSvnchronizaIionfor0FDMSystem摘要相干解调经常应用于正交载波频分复用(OFDM)系统以达到更好的传输性能,但同时要求进行准确地同步。尽管如此,传统的添加前导训练序列的方法大幅地增加了对带宽的占用。在本文中,提出了一种并行的训练序列结构用于对OFDM系统进行同步,该方法将训练序列并行地加到
2、信号流上。本文中,我们将采用m序列作为训练序列对OFDM系统进行高效地频偏估计,在时域上将两段重复的m序列直接加到OFDM符号上,利用m序列优秀的自相关性完成系统的频率同步,与传统的方法相比有效性更高。理论分析与仿真实验结果一致,本文提出的方法可以用于OFDM系统的频率同步。本文还提出了一种新的训练序列,该序列可以应用于高功率信号传输中,称为零子载波叠加训练序列。最后,将两种训练序列应用于系统同步中,对其进行仿真比较。关键词:OFDM;并行训练序列结构;CAZAC/m序列;ML估计算法AbstractCoherentdemodulationisusuallyadopt
3、edinorthogonalfrequencydivisionmultiplexing(OFDM)systemtoachievebetterperformance.Itmeansaccuratesynchronizationaxeneeded.However,traditionalpreambletrainingsequencedecreasesubstantiallybandwidthutilization.Inthisthesis,asuperimposedtrainingschemeforsynchronizationisproposedforOFDMsyste
4、m,wheretrainingsequencearesuperimposedontodatastreamNotethatweaddedthem-sequenceandguardintervalinthetimedomainOFDMsignal.Inthisthesis,weproposeandanalyzeallefficientfrequencyoffsetsynchronizationmethodbasedonm—sequenceofOFDMsystem.Repeatedm-sequenceissuperimposeddirectlytoOFDMframesint
5、hetimedomain.Byutilizingtheautocorrelationcharacteristicsofm-sequence,efficientsynchronizationc锄beachievedwithoutimposingadditionalcomplexity.The仃equencyoffsetestimatorarederivedbasedonthemaximumlikelihoodcriterionboththeoreticalandsimulatedresultsarepresentedtoverifytheproposedfrequenc
6、ysynchronizationmethod.Alsoanewtrainingsequenceisproposedinthisthesiswecallitsuperimposedtrainingsequencewithzeroaddeditwasmadetoovercometheproblemofhi【ghpowerofthetransmittedsignal.SimulationwasmadetocomparebetweenthetwotrainingsequenceKeyword:OFDM;Superimposedtrainingsequence;CAZAC/ms
7、equence,MLalgorithm1.1IntroductionChapter1IntroductionThedemandforhighdatarateserviceshasbeenincreasingveryrapidlyandthereisnoslowdowninsight.Almosteveryexistingphysicalmediumcapableofsupportingbroadbanddatatransmissiontoourhomes,officesandschoolshasbeenorwillbeusedinthefuture.
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