现代无线通信系统电波传播第六章ppt课件.ppt

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1、PropagationinthePresenceofBuildingsonFlatTerrainContents6.1Modelingpropagationoverrowsofbuildings6.1aComponentsofthepathgain6.1bModelingPG2bydiffractionoftherooftopfields6.2ApproachestocomputingthereductionPG1oftherooftopfields6.2aPhysicalopticsapproachtocompotingfieldredution6.2bS

2、olutionsforuniformrowspacingandbuildingheight6.3Planewaveincidenceformacrocellpredictions6.3aSoutionintermsofBorsma'sfuntions6.3bUsingthesettledfieldtofindthepathloss6.4Cylindricalwavetincidenceformicrocellpredictions6.4aSolutionintermsofBorsma"sfuntions6.4bPathlossforlowbasestatio

3、nantennas6.4cPathlossformobile-to-mobilepropagation6.4dPropagationobliquetorowsofbuildings6.5Numericalevaluationoffieldsforvariablebuildingheightandrowspacing6.5aWindowingtoterminatetheintegration6.5bDiscretizationoftheintegration6.5cHeightdependenceofthesettledfield6.5dInfluenceof

4、roofshape6.6SummaryInthischapterweintegratethepropagation,reflection,anddiffractionconceptsofthepreviouschaptersinordertounderstandanpredictthepathlosscharacteristicsthathavebeenobservedoverlargeportionsofmetropolitanregions.BeijingChengdu6.1ModelingpropagationoverrowsofbuildingsTr

5、ansmissionlossthrougharowofhouseswillbe8to14dB.Theradiosignalexperiencesaverylargereducetioninstrengthcomparedtofree-spacepropagation.Propagationpathsinwhichthewavesgooverthebuildingsandarediffracteddowntothesubscribermayinvolvelessexcesspathloss.6.1aComponentsofthepathgainThinking

6、intoaccounttheforegoingdiscussion,thepathgainistheproductofthreefactors:(1)thefree-spacepathgainPG0(2)thereductionPG1inthefieldsarrivingatthebuildingnearthemobileduetodiffractionpastthepreviousrowsofbuildings(3)thereductionPG2inthefieldsastheydiffractdowntogroundlevelWhenexpressedi

7、ndecibels,thepathgainisThefree-spacepathgainforisotropicantennasis6.1bModelingPG2bydiffractionoftherooftopfieldsFourpossiblepathWeaddthepowersoftheindividualraysWetakethefieldsoverbothbuildingtobethoseofhorizontallypropagatingplanewavesofunitamplitudePG2forisotropicantennasisgivenb

8、y6.1bModelingPG2bydiffract