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《ABSTRACT Title of dissertation ENABLING DYNAMIC SPECTRUM ALLOCATION》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。
1、ABSTRACTTitleofdissertation:ENABLINGDYNAMICSPECTRUMALLOCATIONINCOGNITIVERADIONETWORKSYuanYuan,DoctorofPhilosophy,2007Dissertationdirectedby:AssociateProfessorWilliamA.Arbaugh,DepartmentofComputerScienceProfessorAgrawalaAshok,DepartmentofComputerScienceThelastdecade
2、haswitnessedtheproliferationofinnovativewirelesstechnologies,suchasWi-Fi,wirelessmeshnetworks,operatinginunlicensedbands.Duetotheincreas-ingpopularityandthewidedeploymentsofthesetechnologies,theunlicensedbandsbecomeovercrowded.Thewirelessdevicesoperatingintheseband
3、sinterferewitheachotherandhurttheoverallperformance.Tosupportfastgrowthsofwirelesstechnologies,morespectrumsarerequired.However,asmost“prime”spectrumhasbeenallocated,thereisnospectrumavailabletoexpandtheseinnovativewirelessservices.Despitethegeneralperceptionthatth
4、ereisanactualspectralshortage,therecentmeasurementre-sultsreleasedbytheFCC(FederalCommunicationsCommission)showthatonaverageonly5%ofthespectrumfrom30MHzto30GHzisusedintheUS.Thisindicatesthattheinefficientspectrumusageistherootcauseofthespectralshortageproblem.Theref
5、ore,thisdissertationisfocusedonimprovingspectrumutilizationandefficiencyintacklingthespectralshortageproblemtosupportever-growinguserdemandsforwirelessappli-cations.Thisdissertationproposesanovelconceptofdynamicspectrumallocation,whichadaptivelydividesavailablespect
6、rumintonon-overlappingfrequencysegmentsofdif-ferentbandwidthconsideringthenumberofpotentiallyinterferingtransmissionsandthedistributionoftrafficloadinalocalenvironment.Thegoalsare(1)tomaximizespectrumefficiencybyincreasingparalleltransmissionsandreducingco-channelint
7、erferences,and(2)toimprovefairnessacrossanetworkbybalancingspectrumassignments.Sinceex-istingradiosystemsofferverylimitedflexibility,cognitiveradios,whichcansenseandadapttoradioenvironments,areexploitedtosupportsuchadynamicconcept.Weexploretwodirectionstoimprovespec
8、trumefficiencybyadoptingtheproposeddynamicallocationconcept.First,webuildacognitivewirelesssystemcalledKNOWStoexploitunoccupiedfrequenciesinthelic
