基于周期循环平稳检测算法的频谱感知技术研究

基于周期循环平稳检测算法的频谱感知技术研究1基于周期循环平稳检测算法的频谱感知技术研究摘要：认知无线电作为一种革命性智能频谱共享技术，可显著提高频谱的使用率，近年来受到了人们的广泛关注。组建实际认知无线电网络需要解决的核心问题是：如何准确地识别频谱空穴并检测授权用户出现。因此，作为解决这一问题的频谱感知技术是决定认知无线电能否实现的关键技术之一。本文重点研究了基于周期循环平稳检测的频谱感知技术，简单地阐述了频谱感知技术的发展，应用和现状，系统地介绍了实现频谱感知的几种算法并加以比较，详细地论述了周期循环平稳检测算法的原理及实现过程。然后对该算法结合理论和仿真图进行了性能分析。最后，通过仿真说明周期循环平稳检测在低信噪比的情况下仍具有良好的性能，而且能区分不同类型的调制信号。关键词：认知无线电，频谱感知，周期循环平稳检测算法Abstract:Asarevolutionarysmartspectrumsharingtechnology,CRcansignificantlyimprovethespectrumutilizationanddrawmoreandmoreattentionwithintheseyears.Thecoreproblemofconstructingtheactualcognitiveradionetworksishowtofindthespectrumholeandidentifythelicenseusers.Sospectrumsensing,asasolutiontothisproblemplaysavitalroleinCRrealization.Thispaperpresentsthecyclostationaryspectrumdensitydetectionmethodforestimationandspectralautocorrelationfunctiontechniquetoanalyzethespectrum,andshowsthedevelopment,applicationsandstateofspectrumsensing,roundlyintroducescurrentseveralmethodsforspectrumsensingandtherelationofthem,andparticularlyanalyzesbasicprincipleandimplementationofcyclostationarityspectrumdetection,andanalyzesthedominantcyclicfeatures.Moreover,asimulationalanalysissuggeststhatcyclostationaryspectrumdetectionisoptimalforsignaldetectionhavinglowsignal-to-noise(SNR)values.Inaddition,wecandistinguishmodulationsignalsindifferenttypesusingthemethod.Keywords:cognitiveradio,spectrumsensing,cyclostationarityspectrumdetection基于周期循环平稳检测算法的频谱感知技术研究2目录1绪论..............................................................................................................................................31.1研究背景及意义.................................................................................................................31.2研究现状............................................................................................................................61.2.1认知无线电的国内外研究现状..............................................................................61.2.2认知无线电中频谱感知技术的国内外研究现状..................................................81.3本文工作和内容组织......................................................................................................122基于信号周期平稳特性的频谱感知算法基本理论.................................................................132.1引言..................................................................................................................................132.2周期平稳相关概念及定义..............................................................................................132.2.1周期平稳信号.......................................................................................................132.2.2循环谱密度函数...................................................................................................152.2.3循环谱密度函数特点...........................................................................................162.3周期平稳特性的噪声抑制性能.......................................................................................162.4循环谱的估计..................................................................................................................172.4.1谱相关函数的计算................................................................................................172.4.2离散信号的循环谱估计.......................................................................................182.5周期循环检测法..............................................................................................................202.5.1理论分析...............................................................................................................202.5.2算法描述................................................................................................................202.6本章小结..........................................................................................................................213周期循环平稳检测算法性能分析及优势.................................................................................223.1性能分析..........................................................................................................................223.1.1不同窗函数对性能的影响...................................................................................223.1.2检测数据序列长度对性能的影响.......................................................................243.1.3滑动步长对性能的影响.......................................................................................253.1.4信道对性能的影响...............................................................................................273.2周期循环平稳检测算法的主要优势..............................................................................291.系统抗噪声能力强......................................................................................................292.区别不同类型的调制信号..........................................................................................333.3本章小结..........................................................................................................................384全文总结和未来工作展望.........................................................................................................39致谢......................................................................