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ID:40600603
大小:3.87 MB
页数:9页
时间:2019-08-04
《Cognitive radios for spectrum sharing 》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、CognitiveRadiosforSpectrumSharingAnantSahai,ShridharMubaraqMishra,RahulTandra,andKristenAnnWoyachWirelesssystemsrequirespectrumtooperate,butinterferenceislikelyifradiosinphysicalproximitysimultaneouslyoperateonthesameband.Therefore,spectrumisapotentiallyscarceresource;acrosstheplanet
2、today,spectrumisregulatedsothatmostbandsareallocatedexclusivelytoasinglesystemlicensedtousethatbandinanygivenlocation.However,suchstaticspectrumallocationpoliciesleadtosignificantunderuseofspectrum[1].Thiscanbeviewedasakindofregulatoryoverheadthatispaidtogetreliableoperation.Withfrequ
3、ency-agileradiosbecomingcommerciallyfeasiblewithinthenext5-10years,CognitiveRadioisaboutmakingsuchradiossmartenoughtosharespectrumandreducetheregulatoryoverhead.Thisisanimpendingwirelessrevolutionthatdrawsuponmanysignal-processingareasincludingrobustdetection,sensornetworks,aswellast
4、hedesignofincentivesandwaveforms.Thisisashortcolumntouchingontheissues;furthertechnicaldetails/referencescanbefoundin[2].THEOPPORTUNITYINTHETELEVISIONBANDSRightnow,thereissignificantexcitementsurroundingthebroadcasttelevisionbands.TheFederalCommunicationsCommission(FCC)hasstartedconsi
5、deringdynamicapproachesforspectrumsharingandtheIEEEhaslaunchedthe802.22standardsprocesstouseTV-bandspectrumholesforenablingwide-areaInternetservice[3],[4].ThiscontextisillustratedinFigure1.ThebackgroundofFigure1isamapofthecontinentalUSAwiththeshadingrepresentingthepopulationdensity.T
6、hereddotsindicatethelocationsofallTVtransmitterswhilethepurpledotscorrespondtotransmittersforchannel40.ThegreenzoneontheleftzoomsinontheSanFranciscoBayAreatoshowthefootprintswheredifferentstationscanbereceivedwithanelectricfieldstrengthabove41.19dBufor50%ofthelocationsmorethan90%ofthe
7、time.Fromthispicture,itisclearthatspectrumholesareinevitable.Justasavasecanbefilledwithrocksandstillhaveplentyofroomforsand,thereisalwaysgoingtoberoomfornon-interferingradiotransmissionsintheintersticesbetweenchannelfootprints[5].Thelittledarkcirclerepresentstheinterferencefootprintfo
8、rchannel40(w
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