摘要PAGE\*MERGEFORMATIIAbstractPAGE\*MERGEFORMAT6摘要现如今无线通信的技术发展的越来越火热，但同时也会面临这样的问题：频谱的资源变得也来越少。以前处于静态的无线频谱管理的方式会让一些频谱常常处于一种空闲的状态。这些常常处于空闲的状态会限制频谱利用率。如果长时间这样，则会影响频谱的利用率，造成频谱资源的浪费。主要的目的是为了提高频谱的利用率，人们于是提出认知无线电的思想。在基于认知无线电的基础上发展正交频分复用可以降低总的发送功率，由串行的高功率变成多个并行的子载波低功率发送。首先，这篇文章介绍了认知无线电产生的背景和两个对认知无线电的概念的解释，认知无线电特点当中的认知能力更够感应外部环境的检测，分析频谱和对频谱的判定。其次，就OFDM的认知无线电频谱感知做出了一些研究，通过搭建感知的系统模型，研究其功能等特点。对于认知无线电OFDM系统资源分配算法，本节通过简单的介绍了Wong算法、最小容量最大化算法、RA算法、迭代注水算法等，需要找一种多用户资源分配算法当中的最优算法。本章节仿真采用的是典型的迭代注水算法，得出的结论是这个算法的主要是能够实现使功率最小或者速率的最大化。关键词：认知无线电；OFDM；多用户；注水算法AbstractAbstractAbstractNowthetechnologyofwirelesscommunicationisdevelopingmoreandmorehot,butatthesametime,italsowillfacetheproblem:theresourcesofthespectrumbecomemoreandless.Beforethestaticwirelessspectrummanagementapproachwillletsomespectrumisofteninanidlestate.Theseareoftenidleandlimitthespectrumutilization.Ifthisislong,itwillaffecttheutilizationofthespectrum,resultinginthewasteofspectrumresources.Themainpurposeistoimprovetheutilizationofthespectrum,peoplethenputforwardtheideaofcognitiveradio.Thedevelopmentoftheorthogonalfrequencydivisionmultiplexingbasedonthecognitiveradiocanreducethetotaltransmissionpower,andtransmitthehighpowerfromserialtomultipleparallelsubcarrierswithlowpower.First,thisarticleintroducedexplainedthebackgroundofcognitiveradioandtwoofcognitiveradioconcept,cognitiveradiocharacteristicsofcognitivecapacityenoughinductionoftheexternalenvironmentdetection,analysisofspectrumandthespectrumdetermination.Secondly,someresearchismadeonthecognitiveradiospectrumofOFDM,andthefeaturesofthecognitiveradiospectrumsensingsystemarestudied.ForcognitiveradioOFDMresourceallocationalgorithm,inthissection,throughsimpleintroducedWongalgorithm,minimumcapacitymaximizationalgorithm,RAalgorithm,iterativewaterfillingalgorithmandneedtofindamultiuserresourceallocationalgorithmfortheoptimalalgorithm.Thischapterusesatypicaliterativewaterinjectionalgorithm,andtheconclusionisthatthealgorithmcanachievethemaximumoftheminimumpowerorr