基于手机掉线“及”盲区的探究2

Thestudyaboutcell-phone’s“fallline”and“blindzone”

（手机“掉线”及“盲区”旳探究）PhysicalscienceandtechnologyinstituteYangtzeUniversity——物理0801班SpeakerZhuzhonghuPhysicalscienceandtechnologyinstituteYangtzeUniversityTitle1Title2Title3PrinciplesofsignaltransmissionThecausesofcell-phone’s“fallline”and“blindzone”ThestrategiesofimprovingthepropertyofCross-districtswitchContentsTitle4Summary1.1Introductiontotheprincipleofsignaltransmission

PhysicalscienceandtechnologyinstituteYangtzeUniversityThespreadofmobilephonesignalsareactuallytransmittedbyelectromagneticwave.1.2SignaltransmissionPhysicalscienceandtechnologyinstituteYangtzeUniversitySignaltransmissionSurfacespread（地表传播）Sighttransmission（视距传播）Waveguidetransmission（波导传播）Scattertransmission（散射传播）2Thecausesofcell-phone’s“fallline”and“blindzone”PhysicalscienceandtechnologyinstituteYangtzeUniversityFirst

Second

Third

Multipathfading（多径衰落）Interferencefactors（干扰原因）Shieldingeffect（屏蔽效应）ThefailureofCross-districtSwitch（越区切换失败）Fourth

2.4ThefailureofCross-districtSwitchPhysicalscienceandtechnologyinstituteYangtzeUniversityTheconceptThecategoryFailureAnalysisThefailureofCross-districtSwitch2.4.1TheconceptofCross-districtSwitchWhenthemobilestationfromonecell(ofabasestationorbasestationcoveragearea)toanotherarea,inordertomaintainuninterruptedcommunicationsformobileusersneedtochangethechannelreferredtoashandoff.PhysicalscienceandtechnologyinstituteYangtzeUniversity2.4.2Thecategoryofcross-districtswitch(1)Dividedbywhetherthecurrentservicestationissynchronous(同步)withtheservicestationafterswitching:

absolutelysynchronousswitching(完全同步切换）

pre-synchronousswitching（预同步切换）asynchronousswitching（异同步切换）pseudo-synchronousswitching（伪同步切换）PhysicalscienceandtechnologyinstituteYangtzeUniversity(2)Accordingtoareas：Internalswitch（内部切换）Externalswitch（外部切换）(3)AccordingtothecontrollingprocessandswitchesbetweendifferentMSC：Basicswitch（基本切换）Follow-upswitch（后续切换）PhysicalscienceandtechnologyinstituteYangtzeUniversity2.4.3FailureAnalysisPhysicalscienceandtechnologyinstituteYangtzeUniversityIfthenewserviceareaatthistimeisverybusy,ithasnoextrachannelallocationtousers.Atthistime,theswitchoftheserviceareawillfail.Eachbasestationhasitsownscope.Whenauserduringacallbeyondaserviceareatoanotherservicearea,theuserofthevoicechannelshavetobereplacedfromtheoriginalserviceareaover3.ImprovethehandoffperformanceofcommunicationstrategyReservedchannelprogram（保存信道方案）Queuingpriorityprogram（排队优先权方案）Halfspeedprogram（半速方案）PhysicalscienceandtechnologyinstituteYangtzeUniversity4.SummaryPhysicalscienceandtechnologyinstituteYangtzeUniversityThroughmypresentation,Ihopeyouhadlearntsomecommonsenses:Duringacall,youshouldbeinopenare