摘要近些年，我国无线技术得到了快速的发展，并且被广泛的应用在各个领域中，取得了一定的成绩，OFDM技术是非常重用的一种无线通信技术。其主要原因是因为OFDM技术的误码性能低，频谱利用率高，架设成本低等。被数字视频广播(DigitalVideoBroadcasting,DVB)、非对称数字用户线(AsymmetricalDigitalSubscriberLine,ADSL)等无线通信设备所采用。OFDM能够有效的对于多载波的传输的一种方式，能够有效的对于信息信号进行高效率的传播，减少了信息信号之间的干扰。并且能够将高速数据进行分流，加快了数据传播的时效性，被广泛的应用在无线通信中。在OFDM系统中，为了达到良好的传输效果，OFDM系统的发射功率需要达到一定的要求，因此在发射端末端需要增加功率放大器。然而，OFDM信号的较高峰值平均功率比(PeaktoAveragePowerRatio,PAPR)问题限制了其功率的放大，由于功率放大器具有非线性特性，过高的输入峰值会导致信号失真，影响系统性能。因此，尽可能的降低OFDM系统的PAPR以及合理地设计线性放大器也就成为OFDM系统的重点技术。本文基于Saleh模型对行波管放大器进行建模，并使用部分传输序列(PartialTransmitSequence,PTS)来降低OFDM系统的PAPR，观察了信号经过行波管放大器后各项指标的变化。研究PAPR减小以及行波管放大器的非线性对OFDM系统的影响，对部分传输序列算法进行了调整，并在优化算法的基础上研究了OFDM系统的性能。关键词：正交频分复用；峰值平均功率比；行波管放大器建模；部分传输序列ABSTRACTInrecentyears,China'swirelesstechnologyhasbeenrapidlydeveloped,andhasbeenwidelyusedinvariousfields,withcertainachievements.OFDMtechnologyisaveryreusablewirelesscommunicationtechnology.ThemainreasonisthatOFDMtechnologyhaslowerrorcodeperformance,highspectrumutilizationandlowerectioncost.ByDigitalVideobroadcast(DigitalVideoBroadcastinghad,DVB),asymmetricDigitalSubscriberLine(AsymmetricalDigitalSubscriberLine,ADSL)andotherwirelesscommunicationequipment.OFDMisaneffectivewayformulti-carriertransmission,whichcaneffectivelyspreadinformationsignalsefficientlyandreducetheinterferencebetweeninformationsignals.Moreover,itcandistributehigh-speeddataandacceleratethetimelinessofdatatransmission,whichiswidelyusedinwirelesscommunication.InanOFDMsystem,inordertoachievegoodtransmissioneffect,thetransmittingpoweroftheOFDMsystemneedstomeetcertainrequirements,soitisnecessarytoaddpoweramplifiersattheendofthetransmittingend.However,thehighPeaktoAveragePowerRatio(PAPR)ofOFDMsignalslimitsitsPoweramplification.DuetothenonlinearcharacteristicsofPoweramplifiers,toohighinputPeakwillleadtosignaldistortionandaffectthesystemperformance.Therefore,reducingthePAPRofOFDMsystemasmuchaspossibleanddesigningthelinearamplifierreasonablyhavebecomethekeytechnologiesofOFDMsystem.Inthispaper,thePartialtransmissionSequence(PTS)isusedtoreducethePAPRofOFDMsystem,andthechangesofvariousindexesafterthesignalpassesthroughtheTWTamplifierareobserved.TheinfluenceofPAPRreductionandthenonlinearityoftravelling-wavetubeamplifieronOFDMsystemisstudied.Sometransmissionsequencealgorithmsareadjusted,andtheperformanceofOFDMsystemisstudiedonthebasisofoptimizationalgorithm.Keywords:OFDM;PAPR;AmplifierMathematicalModel;PTS目录第一章绪论..........................................................................................................................11.1课题的背景与研究意义.............................................................................................11.2OFDM峰均比问题和功率放大器建模....................................................................21.2.1OFDM峰均比问题.........................................................
