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XXXXXXXXX毕业设计（论文）-I-DS-CDMA移动通信系统的仿真设计与实现摘要随着移动通信的迅猛发展，扩频通信技术在移动通信领域的应用已经步入了一个新的阶段，扩频通信不仅在军事通信方面发挥着不可取代的优势，而且广泛渗透到民用通信的各个方面。而作为扩频通信技术之一的直接序列扩频是在扩频通信中应用最多，技术最成熟的一种频谱扩展方式，是目前应用最广泛的扩频系统。本课题是对直接序列扩频通信系统的仿真设计与实现的研究，通过对系统模型的建立，仿真参数的设计以及系统波形的分析来分析系统的各项性能指标。直接序列扩频通信系统的关键问题是扩频码和地址码的选择及系统的同步，论文采用的扩频编码信号(PN码)由发射机产生，并同载有实际信息的信号同时发送；为了达到伪码的同步，接收端采用同样的伪随机序列进行相关处理，然后采用科斯塔斯环法实现载波同步和伪码的同步。并且在最后对设计仿真结果中的时域波形，系统的频谱图，系统的误码率以及抗干扰性能都做了分析，从而体会并了解到DS-CDMA系统的优势。最终在对各种噪声干扰中，对仿真结果与理论值进行比较，可以得出本系统的仿真设计基本符合要求，并且可以深刻地体会到直接序列扩频通信系统具有良好的抗干扰性能，在未来的移动通信中具有决定性的应用前景。关键词：DS-CDMA；扩频；Systemview仿真；码分多址；伪随机序列；系统同步DS-CDMA移动通信系统仿真设计与实现-II-SimulationDesignandImplementationoftheDS-CDMAMobileCommunicationSystemAbstractWiththerapiddevelopmentofmobilecommunications,thetechnologyofspreadspectrumcommunicationhasenteredanewphaseinthefieldofmobilecommunicationsapplication,itnotonlyplaysanirreplaceableadvantagesinmilitarycommunications,butalsopenetratesintoawiderangeofciviliancommunicationsThedirectsequencespreadspectrumasoneofSpread-spectrumcommunicationawayofspreadspectrumwhichisappliedmostandtrustyintechnology,whichisappliedmostwidely.Thisissuefocusonthestudyofdesignandimplementationofthesimulationdirectsequencespreadspectrumcommunicationsystems,Accordingtothesettingofsystemmodeldesignofsimulationparametersandanalysisofsystemwaveformitwillanalyseallkindsofindexofthesystem.Thekeyofdirectsequencespreadspectrumcommunicationsystemisthechoiceofthecodeofspreadingcodesandaddressesandsystemsynchronization.spreadspectrumencodingsignal(PNcode)whichisusedinthispaperisgeneratedbythetransmitter,andsentwiththesignalwhichcontainactualinformationsimultaneity;inordertoachievesynchronizationofpseudo-code,thereceiverprocessthestatuswiththesamepseudo-randomsequence,andthenusingCostasLoopCarrierSynchronizationMethodforSynchronousandpseudo-codeandthetime-domainwaveform,Thesystem'sfrequencyspectrum,thesystem'sbiterrorrateanti-interferenceperformanceandtheanti-interferenceperformanceofdesignandsimulationresultsareanalyzedfinally,IknowtheadvantagesoftheDS-CDMAsystem.Wecouldgetthatthedesignofthesystemsimulationofthebasicqualificationrequirementsaremet,andrealizethedirectsequencespreadspectrumcommunicationsystemhasagoodanti-interferenceperformancewhensimulationresultsarecomparedwiththetheoreticalvalueinallkindsofnoiseKeywords:spreadspectrumcommunication；Systemviewsimulation；pseudo-randomsequence；thesystemsynchronization；codedivisionmultipleaccessXXXXXXXXX毕业设计（论文）-III-目录第1章绪论..............................................................................................................................11.1扩频产生的背景及意义..............................................................................................11.2扩频的发展与应用......................................................................................................11.3各章内容安排..............................................................................................................2第2章直接扩频通信系统的原理..........................................................................................32.1直接扩频通信系统的组成原理..................................................................................32.1.1理论基础............................................................................................................32.1.2扩频原理............................................................................................................42.2性能分析......................................................................................................................52.2.1抗干扰性能........................................................................................................62.2.2信噪比和误码率................................................................................................72.2.3多址功能............................................................................................................92.3直接扩频通信系统关键技术研究............................................................................102.3.1伪随机序列......................................................................................................102.3.2编码与解码......................................................................................................112.3.3调制与解调......................................................................................................122.3.4扩频信号的解扩..............................................................................................142.3.5系统同步原理..................................................................................................152.4本章小结....................................................................................................................17第3章DS-CDMA系统仿真设计与实现............................................................................193.1Systemview动态软件简介........................................................................................193.2仿真系统的设计........................................................................................................193.3系统的参数计算与设定.................................................................