通信工程毕业设计的论文外文翻译一个新的协作频谱感知算法认知无线电络

毕业设计（论文）外文参考资料及译文译文题目：一个新的协作频谱感知算法认知无线电网络学生姓名：学号：专业：通信工程所在学院：龙蟠学院指导教师：田甜职称：讲师2011年12月1日说明：要求学生结合毕业设计（论文）课题参阅一篇以上的外文资料，并翻译至少一万印刷符（或译出3千汉字）以上的译文。译文原则上要求打印（如手写，一律用400字方格稿纸书写），连同学校提供的统一封面及英文原文装订，于毕业设计（论文）工作开始后2周内完成，作为成绩考核的一部分。ANewCooperativeSpectrumSensingAlgorithmforCognitiveRadioNetworksAbstract—spectrumsensingisacriticalphaseinbuildingacognitiveradionetwork.However,thebandwidthforreportingsecondaryusers’sensingresultswillbeinsufficient,whenthenumberofsecondaryuserisverylarge.Inthispaper,weproposeanewcooperativespectrumsensingalgorithmtoalleviatethebandwidthproblemofreportingchannel.Comparedwithconventionalmethod,onlythesecondaryuserswithreliableinformationareallowedtoreporttheirsensingresults.Whennouserwithreliableinformation,onlythesecondaryuserwithhighestreputationwillreportitssensingresult.Simulationresultsshowthatouralgorithmachievesbettersensingperformanceandtheaveragenumberofsensingbitsdecreasegreatly.Keywords—cognitiveradio;cooperativespectrumsensing;doublethreshold;reputationⅠ.INTRODUCTIONDuetotheincreasinglydevelopmentofwirelessapplications,moreandmorespectrumresourcesareneededtosupportnumerousemergingwirelessservice.However,recentmeasurementsbyFederalCommunicationCommission(FCC)haveshownthat70%oftheallocatedspectruminUSisnotutilized[1].Inordertoincreasetheefficiencyofspectrumutilization,cognitiveradiotechnologywasrecentlyproposed[2],[3].Arequirementofcognitiveradiosisthattheirtransmissionshouldnotcauseharmfulinterferencetoprimaryusers.Namely,thesecondaryuserscanusethelicensedspectrumaslongastheprimaryuserisabsent.However,whentheprimaryusercomesbackintooperation,thesecondaryusersshouldvacatethespectruminstantlytoavoidinterferencewiththeprimaryuser.Accordingly,spectrumsensingisacrucialphaseinbuildingacognitiveradiosystem.Oneofthegreatchallengesofimplementingspectrumsensingisthehiddenterminalproblemwhichcausedbythefadingofthechannelsandtheshadowingeffects.Inordertodealwiththehiddenterminalproblem,cooperativespectrumsensinghasbeenstudiedtoimprovethespectrumsensingperformance[4],[5].In[6],duetocontrolchannelforeachcognitiveradiotoreportitssensingresultisusuallybandwidthlimited,acensoringmethodwhichhastwothresholdsisgiventodecreasetheaveragenumberofsensingbitstothecommonreceiver.Bycensoringthecollectedlocalobservations,onlythesecondaryuserswithenoughinformationwillsendtheirlocaldecisionstothecommonreceiver.Inthispaper,wepresentanewdoublethresholdcooperativespectrumsensingmethodwithreputation.Inoursystem,everycognitiveuserwillfirstlyobtainanobservationindependentlyandonlytheuserswithreliableinformationsendtheirlocaldecisionstothecommonreceiverbasedondoublethresholds.Ifnouserisreliable,onlythecognitiveuserwiththehighestreputationisselectedtosensethespectrum.SimulationresultsshowthatthespectrumsensingperformanceunderAWGNchannelsisimprovedandthecommunicationtrafficisalsoreducedasopposedtotheconventionalmethod.Therestofthepaperisorganizedasfollows.InsectionⅡ,systemmodelisbrieflyintroduced.SensingperformanceisanalyzedinSectionⅢ.InSectionⅣ,wepresentthesimulationresultsofourcooperativespectrumsensingmethod.Finally,wedrawourconclusionsinSectionⅤ.II.SYSTEMMODELIncognitiveradiosystems,spectrumsensingisacriticalelementasitshouldbefirstlyperformedbeforeallowingsecondaryuserstoaccessavacantlicensedchannel.Cooperativespectrumsensinghasbeenwidelyusedtodetecttheprimaryuserwithahighagilityandaccuracy.Theessenceofspectrumsensingisabinaryhypothesis-testingproblem:0H:primaryuserisabsent;1H:primaryuserispresent.Forimplementationsimplicity,werestrictourselvestoenergydetectioninthespectrumsensing.Thelocalspectrumsensingistodecidebetweenthefollowingtwohypotheses:01(),,()()()(),ntHxthtstntH(1)Where)(txisthesignalreceivedbysecondaryuser,)(tsisprimaryuser’stransmittedsignal,)(tnisAWGN,and)(thisthetemporaryamplitudegainofthechannel.Accordingtoenergydetectiontheory[7],wehavethefollowingdistribution:122022),(,~HXHXmm(2)Whereistheenergyvaluecollectedbysecondaryuser,isinstantaneousSNRandfollowsexponentiallydistributionwiththemeanvalue_,misthetimebandwidthproductoftheenergydetector,22mrepresentsacentralchi-squaredistributionwith2mdegreesoffreedomand.)(22mrepresentsanon-centralchi-squaredistributionwithm2degreesoffreedomandanon-centralityparameter2.Inconventionalenergydetectionmethod,thelocaldecisionismadebycomparingtheobservationwithapre-fixedthresholdasFig.1(a).Whenthecollectedenergyexceedsthethreshold,decision0Hwillbemade.Otherwisedecision1Hwillbemade.Incontrast,thesystemmodelwhichhastwothresholdsofourinterestisshowninFig.1(b).Where“Decision0H”and“Decision1H”representtheabsenceandthepresenceoflicenseduser,respectively.“Nodecision”meansthattheobservationisnotreliableenoughandtheithcognitiveuserwillsendnothingtothecommonreceiver.Butwhenallthesecondaryusersdon’tsendtheirlocaldecisions,onlythecognitiveuserwiththehighestreputationisselectedtosensespectrumbasedonconventionalenergydetectionmethod,andsenditslocaldecisiontothecommonreceiver.Reputationisobtainedbasedontheaccuracyofcognitiveuser’ssensingresults.Thereputation