implementation issues in spectrum sensing for cognitive radios

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1、ImplementationIssuesinSpectrumSensingforCognitiveRadiosDanijelaCabric,ShridharMubaraqMishra,RobertW.BrodersenBerkeleyWirelessResearchCenter,UniversityofCalifornia,BerkeleyAbstract-Therearenewsystemimplementationchallengesinvolvedinthedesignofcognitiveradios,whichhaveboth

2、theabilitytosensethespectralenvironmentandtheflexibilitytoadapttransmissionparameterstomaximizesystemcapacitywhileco-existingwithlegacywirelessnetworks.Thecriticaldesignproblemistheneedtoprocessmulti-gigahertzwidebandwidthandreliablydetectpresenceofprimaryusers.Thisplace

3、ssevererequirementsonsensitivity,linearity,anddynamicrangeofthecircuitryintheRFfront-end.Toimproveradiosensitivityofthesensingfunctionthroughprocessinggainweinvestigatedthreedigitalsignalprocessingtechniques:matchedfiltering,energydetection,andcyclostationaryfeaturedetec

4、tion.Ouranalysisshowsthatcyclostationaryfeaturedetectionhasadvantagesduetoitsabilitytodifferentiatemodulatedsignals,interferenceandnoiseinlowsignaltonoiseratios.Inaddition,toFigure1.Measurementof0-6GHzspectrumutilizationatBWRCfurtherimprovethesensingreliability,theadvant

5、ageofaMACcreatingtimeandlocationdependentin“virtualunlicensedprotocolthatexploitscooperationamongmanycognitiveusersisbands”,i.e.bandsthataresharedwithprimaryusers.Uniqueinvestigated.tocognitiveradiooperationistherequirementthattheradioisabletosensetheenvironmentoverhuges

6、wathsofspectrumI.INTRODUCTIONandadapttoitsincetheradiodoesnothaveprimaryrightstoanypre-assignedfrequencies.ThisnewradiofunctionalityItiscommonlybelievedthatthereisaspectrumscarcityatwillinvolvethedesignofvariousanalog,digital,andnetworkfrequenciesthatcanbeeconomicallyuse

7、dforwirelessprocessingtechniquesinordertomeetchallengingradiocommunications.Thisconcernhasarisenfromtheintensesensitivityrequirementsandwidebandfrequencyagility.competitionforuseofspectraatfrequenciesbelow3GHz.Spectrumsensingisbestaddressedasacross-layerdesignTheFederalC

8、ommunicationsCommission’s(FCC)frequencyproblem.Cognitiveradiosensitivitycanbeimprovedbyallocationcharti