SatelliteCommunications: LinkBugdetFranciscoJ.EscribanoOctober23,2014FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 1/56Tableofcontents1Motivation2ReceivedPower3Attenuation4NoiseAntennaReceiver5Carrier-to-NoisePowerRatio6Intermodulation7Interferences8ConclusionsUplinkDownlink9ReferencesFranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 2/56MotivationMotivationFranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 3/56MotivationSatellitelinkObjectiveofthesatellitelink:Deliverserviceswiththebestqualityandreliability, understrictcostconstraints.Designtarget:Accurately analyzethemainfactorsinvolved,suchassystemcharacter-isticsandpropagation model.Figure1: Systemmodel.FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 4/56MotivationImportantsidefactorsSidefactorstobetakenintoaccount:Satellitesizeandweight.Functionsdeveloped.Assignedfrequencies.TerrestrialStationsdimensions.Mediumaccesstechniques.Mainreferences: [1],[2],[3],[4],[5],[6],[7],[8].FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 5/56ReceivedPowerReceivedPowerFranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 6/56ReceivedPowerPower radiatedbyanantennaRadiatedpowerintensity.Power radiatedbytheantennapersolidangle.TotalradiatedpowerisPT.Ingeneral,U (, ) =dP(,)dWsr1.Ifthepowerisradiatedisotropically,U (, ) =PT4Wsr1.Figure2: Directional antennaradiationpattern.FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 7/56ReceivedPowerAntennagainThegainisdenedastheratiooftheactualradiatedintensitytotheintensityoftheisotropicequivalent.Gainasafunctionofthedirection,G (, ) =U(,)PT/4Maximalgain,GMAX=UMAXPT/4.Gainofanantena: G(dBi) = 10 log10 (GMAX).dBimeanswearetakingascomparisontheistropiccase.Figure3: Directional antennaradiationpattern.FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 8/56ReceivedPowerRadiationpatternThepowercapturedbyanantennadependsonitsradiationpattern.3dBbeamwidth,foraparabolicreector, 3dB 70 Do(degrees).isthewavelength,Dthediameteroftheparaboloid.Figure4: Beamwidth.Figure5: Gainversusangle.FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 9/56ReceivedPowerPower densityEquivalentIsotropicRadiatedPower (EIRP).EIRP(, )=PT G (, ).Power irradiatedperunitarea(powerdensityux).Figure6: Isotropicantenna. =PT4d2.Figure7: Directional antenna.(, ) =PT4d2 G (, ).disthedistancetotheantenna.(, ) =EIRP(,)4d2.FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 10/56ReceivedPowerReceivedpowerApertureareaARe= R2= D24.EectiveareaARe= ARe.: eciency (ratio of the eec-tively captured power to total incidentpower).Figure8: ParaboloidwithdiameterD.PR= ARe.GR=42 ARe= _D_2.Receivedpower:PR=EIRP4d2 ARe=EIRP4d2GR24=EIRPGR(4d)2.FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 11/56AttenuationAttenuationFranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 12/56AttenuationFreespacelossesMedium: homogeneous,istropicandnoobstacles.lfs=_4d_2,ddistancefromtheemitter.Lfs(dB) = 92.44 + 20 log f + 20 log d,f inGHz,dinKm.Figure9: Freespacelossesatdierentfrequencies.Thesearetheminimumpossiblelossesinalink.For a geostationary sat (d 35786 Kmover the Equator),theyarearound200dB.FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 13/56AttenuationPointinglossesNearthemaximal radiationdirection,foradeviationof 3dB,theantennagaincanbeapproximatedas:G(dB) GMAX12 _3dB_2.LptTx 12 _eTx3dBTx_2LptRx 12 _eRx3dBRx_2Figure10: Pointingmismatch.Whenconsidering the satellite antenna coverage, it is necessary toadjust3dBatthecoverageedge.FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 14/56AttenuationAtmosphericpropagation impairmentsPropagationimpairment Physical cause PrimeimportanceAttenation and sky noise in-creaseAtmosphericgases, clouds,rain Fequencies above around 10GHzSignal depolarization Rain,icecrystals Dual-polarization systems at CandKubands(dependsonsys-temconguration)Refraction, atmospheric multi-pathAtmosphericgasses CommunicationandtrackingatlowelevationanglesSignal scintillations Tropospheric and ionospheric re-fractivityuctuationsTropospheric at frequenciesabove 10 GHz and low ele-vation angles; ionospheric atfrequenciesbelow10GHzReectionmultipath,blockage Earthssurface, objetctsonsur-faceMobilesatelliteservicesPropagationdelays,variations Troposphere, ionosphere Precisetimingandlocationsys-tems; timedivisionmultipleac-cess(TDMA)systemsIntersysteminterference Ducting,scatter,diraction MainlyC band;rainscattermaybesignicantathigherfrequen-ciesTable1: PropagationconcernsforSatelliteCommunicationSystems.FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 15/56AttenuationAttenuationduetorainTheattenuationduetorainiscalculatedaccordingtoITU-R.PN618asARAIN(dB) = R LE.R(dB/Km)isthespecicattenuationduetorain.LE(Km)istheeectivelinklengthaccrosstherain.The specic attenuation depends onthe quantity of precipitations and onthefrequency.These data are based on statisticalestimations recordedthroughout thedierentgeographicalregions.Figure11: RainydayinSwitzerland.FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 16/56AttenuationR, LEcalculationsIRainheight(Km)asafunctionoflatitude:hR=_4 , 0 36o.Trajectoryaccrosstherain(Km)asafunctionoftheelevation:LS=hRhSsin(El)whenEl > 5o.Raininhomogeneityfactor:r0.01=9090+4LS cos(El).Theeectivelength(Km)results:LE= LS r0.01.Figure12: Rainyatmospheremodel.FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 17/56AttenuationR, LEcalculationsIIDetermine R0.01(mm/h), precipitations exceded 0.01% of the time dur-inganaverageyear.Thisisdonewiththehelpofrecordedprecipitationmaps.Figure13: RainproleinAmerica.Figure14: RainproleinAfroeurope.Figure15: RainproleinAsia.FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 18/56AttenuationR, LEcalculationsIIIOnceR0.01iscalculated, onepossibility is tocalculate Rwith the help of a so-callednomogram.Figure16: Nomogram.FranciscoJ.Escribano SatelliteCommunications: LinkBugdet October23,2014 19/56AttenuationR, LEcalculationsIVOtherpossibilitytocalculateRasreportedinITU-R.P838:R= k (R0.01)k=_4.21 105 f2.42, 2.9