频分复用(OFDM)系统的原理.doc

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1、Onwirelesscommunication,thehighrateandhighqualityofcommunicationservicearerequiredtooffer,andOFDMhastheadvantageofthehighbandwidthefficiencyandstronganti-multipathability,soOFDMreceiveswidespreadattentioninrecentyears.OFDMisactuallyonekindofmulti-carriermodulation.andthemainideaofOF

2、DMisChannelwillbedividedintoseveralsubchannelsorthogonal,andthenturnHigh-speeddatasignalsintoparallellow-speeddata-flow,modulationineachofthesubchannelsontransmission.ThedesignistheuseofMATLABdesignastructured,modular,graphicalsimulationsoftware.ToprovidesimulationplatformforOFDMtec

3、hnology.OFDMisrequiredtocompletethesimulationmodeling.Themajorsignalmapping,modulation,andothersub-module.SignalmappingmodulewhichisbasedonthecorrespondingmodulationencodingeachbitTableGroupintoaplural.Afterstringandtheconversionofbinarydata,Roadmaponeachdividedintotwogroupsabit,Bym

4、aptheQAMconstellationintoplural.Byusinglook-uptablemethodQAMconstellationismapped.QAMconstellationisdrawn.AndmodulationordemodulationmodulecanbeusedtoachieveIFFTorFFT.OFDMsystemsareusedmorecoherentdemodulation.Whenreceiverdataisdemodulation,Channelestimationneedtocorrectbythefrequen

5、cyselectivefadingandsub-carrierfrequencyoffsettherandomphaseshiftandthemagnitudeofthedecline.Otherwise,thebiterrorrateperformanceisverydifficulttoachievepracticalrequirements.ChannelestimationisusedLMSchannelestimationalgorithm.FinallyadditivewhiteGaussiannoisechannelsofsignal-to-no

6、iseratio(SNR)-biterrorcurvesisdrawn.KEYWORDSwirelesscommunication,multicarriermodulation,OFDM,ChannelEstimation目录摘要IABSTRACTII第一章绪论11.1正交频分复用（OFDM）的来源11.2正交频分复用（OFDM）的研究背景11.2.1无线通信的发展11.2.2第4代（4G）无线通信系统21.3正交频分复用（OFDM）的意义21.3.1正交频分复用（OFDM）的优点21.3.2正交频分复用（OFDM）的不足之处41.4多载波技术的发展4第二章频

7、分复用（OFDM）系统的原理62.1多载波调制基础62.2频分复用（OFDM）系统的技术原理62.2.1OFDM的基本原理72.2.2信号映射(mapping)72.2.3OFDM系统的数学模型112.2.4用DFT实现OFDM的调制与解调142.2.5FFT/IFFT142.2.6保护间隔和循环前缀152.2.7交织172.2.8OFDM的同步技术172.2.9OFDM系统的重要参数设计18第三章OFDM系统的仿真设计203.1OFDM的MATLAB仿真203.1.1MATLAB语言简介203.1.2正交频分复用（OFDM）仿真系统说明213.1.3仿真程序

8、说明233.1.4调试过程和结果分析3