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ThePhysicalLayerChapter2RadioTransmission(a)IntheVLF,LF,andMFbands,radiowavesfollowthecurvatureoftheearth.(b)IntheHFband,theybounceofftheionosphere.PoliticsoftheElectromagneticSpectrumTheISMbandsintheUnitedStates.CommunicationSatellitesa)GeostationarySatellitesb)Medium-EarthOrbitSatellitesc)Low-EarthOrbitSatellitesd)SatellitesversusFiberCommunicationSatellitesCommunicationsatellitesandsomeoftheirproperties,includingaltitudeabovetheearth,round-tripdelaytimeandnumberofsatellitesneededforglobalcoverage.CommunicationSatellites(2)Theprincipalsatellitebands.CommunicationSatellites(3)VSATsusingahub.Low-EarthOrbitSatellitesIridium(a)TheIridiumsatellitesfromsixnecklacesaroundtheearth.(b)1628movingcellscovertheearth.Globalstar(a)Relayinginspace.(b)Relayingontheground.GSMGlobalSystemforMobileCommunicationsGSMuses124frequencychannels,eachofwhichusesaneight-slotTDMsystemGSM(2)AportionoftheGSMframingstructure.CDMA–CodeDivisionMultipleAccess(a)Binarychipsequencesforfourstations(b)Bipolarchipsequences(c)Sixexamplesoftransmissions(d)RecoveryofstationC’ssignalThird-GenerationMobilePhones:DigitalVoiceandDataBasicservicesanIMT-2000networkshouldprovidea)High-qualityvoicetransmissionb)Messaging(replacee-mail,fax,SMS,chat,etc.)c)Multimedia(music,videos,films,TV,etc.)d)Internetaccess(websurfing,w/multimedia.)CableTelevisiona)CommunityAntennaTelevisionb)InternetoverCablec)SpectrumAllocationd)CableModemse)ADSLversusCableCommunityAntennaTelevisionAnearlycabletelevisionsystem.InternetoverCableCabletelevisionInternetoverCable(2)Thefixedtelephonesystem.SpectrumAllocationFrequencyallocationinatypicalcableTVsystemusedforInternetaccessCableModemsTypicaldetailsoftheupstreamanddownstreamchannelsinNorthAmerica.