卷积码的设计与实现

湖南文理学院课程设计报告课程名称：通信系统课程设计院部：电气与信息工程学院专业班级：学生姓名：指导教师：完成时间：2011年12月29日报告成绩：评阅意见：评阅教师日期2目录目录............................................................................................................................................................2摘要............................................................................................................................................................3Abstract......................................................................................................................................................4一、引言....................................................................................................................................................51.1设计任务及基本要求.................................................................................................................51.2设计目的.....................................................................................................................................61.3设计所用仪器设备....................................................................................错误!未定义书签。二、基本概念............................................................................................................................................62.1卷积码的编码原理....................................................................................................................62.2卷积码编码描述........................................................................................................................62.3卷积码译码描述........................................................................................................................6三、卷积码的编译码原理........................................................................................................................63.1卷积码的图形描述.....................................................................................................................63.1.1树状图............................................................................................................................83.1.2网格图............................................................................................................................83.1.3状态图............................................................................................................................93.2卷积积码的编码算法........................................................................................................93.3卷积码的Viterbi译码...................................................................................................10四、卷积码的仿真及性能分析..............................................................................................................124.1SIMULINK仿真模块.................................................................................................................124.2卷积码的参数对误码率的影响..............................................................................................134.2.1码率对误码性能的影响..............................................................................................134.2.2约束长度对误码性能的影响......................................................................................154.2.3回溯长度对卷积码性能的影响..................................................................................164.3仿真分析..................................................................................................................................17总结..........................................................................................................................................................18参考文献：..............................................................................................................................................193摘要卷积码是深度空间通信系统和无线通信系统中常用的一种差错控制编码。在编码过程中,卷积码充分利用了各码字间的相关性。在与分组码同样的码率和设备复杂性的条件下,无论从理论上还是从实践上都证明,卷积码的性能都比分组码具有优势。而且卷积码在实现最佳译码方面也较分组码容易。因此卷积码广泛应用于卫星通信，CDMA数字移动通信等通信系统，是很有前途的一种编码方式。对其进行研究有很大的现实意义。为了解决传统的维特比译码器结构复杂、译码速度慢、消耗资源大的问题，提出一种新型的适用于FPGA特点，路径存储于译码输出并行工作，同步存储路径矢量和状态矢量的译码器设计方案。该设计方案通过在ISE.2i中仿真验证，译码结果正确，得到编码前的原始码元，速度显著提高，译码器复杂程度明显降低。并在实际的软件无线电通信系统中信道编解码部分得到应用，性能优良。关键词：卷积码；误码性能；原理4AbstractConvolutioncodeisdeepspacecommunicationsystemandwirelesscommunicationsystemnowadays.buttheerror-controllingcodes.Thecodingprocess,convolutioncodemakesfulluseofthecorrelationbetweeneachcodewords.Withthesamecodeblockcoderateandequipmentandthecomplexityofconditions,eitherintheoryorinpracticeprovedthattheperformanceofconvolutioncodethanblockcodehasadvantage.Andconvolutioncodeintherealizationoftheoptimaldecodingwithblockcodeeasier.Thereforeconvolutioncodeiswidelyappliedinsatellitecommunications,suchasCDMAdigitalmobilecommunicationsystem,isverypromisingaencoding.Conductstheresearchhasgreatpracticalsignificance.Inordertosolvethetraditionalvictorthandecoderstructureiscomplex,decodingspeedisslow,consumeresourcesbigproblems,andputforwardanewkindofapplicabletotheFPGAcharacteristics,thepathstoredindecodingoutputparallelwork,synchronousstoragepathvectorandstatevectordecoderdesignscheme.Thedesignthrough2iISE.Insimulationtest,decodingofresultsarecorrect,getbe