无线移动互联网：原理、技术与应用 教学课件 作者 崔勇 CH1 Wireless and Mobile Internet Fundamentals.ppt

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1、WirelessandMobileNetworksFundamentalsCS80240333Instructor:CUIYong1OutlineIntroductionWirelessandmobiletechnologyCharacteristicandchallengesProtocolandorganizationforstandardizationCourseArrangementRadiointerfacetechnologyMobileAdhocnetworkWirelessSensorNetworkWirelessMesh

2、NetworkMobileIPWirelessTCP2OutlineIntroductionWirelessandmobiletechnologyCharacteristicandchallengesProtocolandorganizationforstandardizationCourseArrangementRadiointerfacetechnologyMobileAdhocnetworkWirelessSensorNetworkWirelessMeshNetworkMobileIPWirelessTCP3Wirelessandm

3、obiletechnologyTwoimportant(butdifferent)challengesWireless:communicationoverwirelesslinkMobility:handlingthemobileuserwhochangespointofattachmenttonetwork4WirelessCommunicationTransmittingvoiceanddatausingelectromagneticwavesinopenspaceElectromagneticwavesTravelatspeedof

4、light(c=3x108m/s)Hasafrequency(f)andwavelength(l)c=fxlHigherfrequencymeanshigherenergyphotonsThehighertheenergyphotonthemorepenetratingistheradiationLongwave:100-1000m(30-300kHz)v.s.Shortwave:20-200m(150-1500kHz)5RadioPropagationMechanismsThephysicalmechanismsthatgovernra

5、diopropagationarecomplexanddiverse,butgenerallyattributedtothefollowingthreefactors:ReflectionDiffractionScattering6RadioPropagationMechanismsReflectionOccurswhenwavesimpingesuponanobstructionthatismuchlargerinsizecomparedtothewavelengthofthesignalExample:reflectionsfrome

6、arthandbuildingsThesereflectionsmayinterferewiththeoriginalsignalconstructivelyordestructively7RadioPropagationMechanismsBuildingBlocksRR:ReflectiontransmitterreceiverStreet8RadioPropagationMechanismsDiffractionOccurswhentheradiopathbetweensenderandreceiverisobstructedbya

7、nimpenetrablebodyandbyasurfacewithsharpirregularities(edges)Explainshowradiosignalscantravelurbanandruralenvironmentswithoutaline-of-sightpath9RadioPropagationMechanismsBuildingBlocksDRR:ReflectionD:DiffractiontransmitterreceiverStreet10RadioPropagationMechanismsScatterin

8、gOccurswhentheradiochannelcontainsobjectswhosesizesareontheorderofthewavelengthorlessofthepropag