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Chapter2:TheCellularConcept-SystemDesignFundamentals2.1TheConcept:CellularNetworksgeometricshapesCellularcoveragerepresentationMacrocelllarge,coveringawidearerangeofseveralhundredkilometres(km)totenkmmostlydeployedinruralandsparselypopulatedareasMicrocellmediumcell,coverageareasmallerthaninmacrocellsrangeofseveralhundredmeterstoacoupleofmetresdeployedmostlyincrowdedareas,stadiums,shoppingmallsPicocellsmall,coveringaverysmallarearangeofseveraltensofmetreslowpowerantennas,indoorThreedifferentkindsofcellsBasestationtransmittersCcanbeusedasameasureofcapacityAmobilecommunicationsystemusesafrequencyreusefactorof1/7and416channelsavailable.If21channelsareallocatedascontrolchannels,computeitssystemcapacity.Assumeachannelsupports8usersChannelsavailableforallocation=416-21=395ChannelNumberofacell=395/7=57Numberofsimultaneoususerspercell=8x57=456Numberofsimultaneoususersinsystem=7x456=3192Methodoflocatingco-channelcellsChannelAssignmentStrategies:DynamicchannelassignmentMSCallocatesfrequencieswhenacallismadeProvideshighchannelutilizationTodothisitneedsreal-timeinformationonchanneloccupancytrafficdistributionradiosignalstrengthindication(RSSI)highcomputationalloadandincreasedstorageHandover(Handoff)HandoverProcessIllustrationofahandoffscenarioatcellboundaryThebasicconceptofhandoverstrategiesChoosingHandoverMarginsSettingHandoverThresholdsHandoffindifferentsystemInterferenceandSystemCapacity:7-cellreusepatternSixEffectiveInterferingCellsofCell1Co-channelreuseratioQ12-cellreusepattern19-cellreusepatternCo-channelreuseratiovs.frequencyreusepatternTradeoffPropagationmodelCo-channelinterferenceratioExample2Moreexactgeometryfortheco-channelinterferencesS/Iisapproximatedas2.5TrunkingandGradeofService(GOS)GradeofService(GOS)AboutErlangErlangBformulaTrunkedmobilenetworkprovidecellularserviceinthisarea.Systemhas394cellswith19channelseach.Findthenumberofusersthatcanbesupportedat2%blockingifeachuseraveragestwocallsperhouratanaveragecalldurationofthreeminutes.Computethet
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