beamforming antennas(波束形成天線)

BeamformingAntennasfor

WirelessCommunications

YikunHuang,Ph.D.ECE/CCBYikun@November242003OutlinePhasedArrayAntennas

VectorAntennas

BeamformingantennasforWLAN

ConclusionIntroductionBeamforminganditsapplicationsBeamformingantennasvs.omnidirectionalantennasDirectionofarrival(DOA)estimationBeamformingBasicconfigurations:fixedarrayandadaptivearraysmartantennasystems:switchedarrayandadaptivearrayDOAandpolarizationsuperCART3-loopand2-loopvectorantennaarrayDirectionofarrival(DOA)estimationVectorantennavs.phasedarrayantennaInfrastructuremodeAnindoorWLANdesignAdhocmodeAdhocWLANforruralareaApplicationsDescriptionRADARPhasedarrayRADAR;airtrafficcontrol;syntheticapertureRADARSONARSourcelocationandclassificationCommunicationsSmartantennasystems;

Directionaltransmissionandreception;sectorbroadcastinsatellitecommunicationsImagingUltrasonic;optical;tomographicGeophysicalExplorationEarthcrustmapping;oilexplorationAstrophysicalExplorationHighresolutionimagingofuniverseBiomedicalNeuronalspikediscrimination;fetalheartmonitoring;tissuehyperthermia;hearingaidsSource:B.D.VanVeenandK.M.Buckley,UniversityofMichigan,“Beamforming:AVersatileapproachtospatialfiltering”,1988ApplicationsofbeamformingtechnologyPhasedarrayRADARPhasedarrayspikesortingSortedSpikeofindividualneurons.12341656789141513121110NeuronalspikesrecordedbyelectrodearrayPhasedarrayspikesortingsystemCenterforComputationalBiology,MSUPatterns,beamwidth&GainIsotropicdipoletopview(horizontal)sideview(vertical)half-wavedipolebeamformerHalf-powerbeamwidthHalf-powerbeamwidthHalf-powerbeamwidthMainlobesidelobesnulls78°Beamformersvs.omnidirectionalantennasBeamformershavemuchhigherGainthanomnidirectionalantennas:Increasecoverageandreducenumberofantennas!Gain:Beamformersvs.omnidirectionalantennas2)Beamformerscanrejectinterferencewhileomnidirectionalantennascan’t:ImproveSNRandsystemcapacity!3)Beamformersdirectionallysenddownlinkinformationtotheuserswhileomnidirectionalantennascan’t:saveenergy!userinterferenceuserinterferencenullBeamformersvs.omnidirectionalantennasuserusernullmultipath4)BeamformersprovideN-folddiversityGainofomnidirectionalantennas:increasesystemcapacity(SDMA)5)Beamformerssuppressdelayspread:improvesignalqualityDOAestimationphasedelay1234567NN-2N-1N-3…………dPlanewaveBeamformingphaseshifters1234567NN-2N-1N-3………………1,,k2,,k3,,k4,,k5,,k6,,k7,,kN-3,,kN-2,,kN-1,,kN,,kphasedarray(fixed/adaptive)configurations-timedomainBasicphasedarrayconfigurationsNarrowbandsN(k)s2(k)s1(k)...w*Nw*2w*1broadbandsN(k)s2(k)s1(k)...w*N,0w*N,1w*N,k-1...Z-1Z-1w*2,0w*2,1w*2,k-1...Z-1Z-1w*1,0w*1,1w*1,k-1...Z-1Z-1phasedarray(fixed/adaptive)configuration-frequencydomainBasicphasedarrayconfigurations………sN(k)s2(k)s1(k)...-+IFFTMSEFFTw*Nw*2w*1FFTFFTFFTbroadband...SmartantennasystemsMilitarynetworks

Cellularcommunicationnetworks

Wirelesslocalareanetworks

switchedarrayadaptivearrayswitchedarrayadaptivearrayswitchedarrayadaptivearrayWi-FiDatarate:11Mbps3GDatarate:100kbpsSwitchedarray(predetermined)topview(horizontal)Smartantennasystemsinterferenceuser12345678910111213141516user1Interference1topview(horizontal)user2SmartantennasystemsInterference2Adaptivearray

Smartantennasystem12100

Indoorrange(MixedOffice)

11Mbps:upto300m5.5Mbps:upto400m2Mbps:upto500m1Mbps:upto600m

Outdoorrange(outdoortoindoor)11Mbps:upto1.00km5.5Mbps:upto1.25km2Mbps:upto2.00km1Mbps:upto2.50kmOutdoorrange(outdoortooutdoor)11Mbps:upto4.20km5.5Mbps:upto5.10km2Mbps:upto6.00km1Mbps:upto7.20kmActiveuserperswitch100Example:Vivato2.4GHzindoor&outdoorWi-FiSwitches(EIRP=44dBm;Gain=25dBi;3-beam)PolarizationcircularElinear=0EEellipse=45XYZ

’EE=90ESuperCARTCompactarrayradiolocationtechnologyFlam&Russell,Inc.,1990U.S.PatentNo.,5,300,885;1994Frequencyrange:2–30MHzSuperCART3-loopV6V4V3V1V2V5YXkb0.5b2-loopHESSteeringvectorBlindpointVectorantennasvs.spatialarrayantennasVectorantennasmeasure:,,,,

and

powersimultaneously,nophaseshiftdevice,orsynchronizationisneeded.

Phasedarrayantennaswithomnidirectionalelementmeasure:,,

and

powerSource:Nehorai,A.,UniversityofIllinoisatChicagoVectorantennasvs.spatialarrayantennasVASAVASAVectorantennasvs.spatialarrayantennasPhasedarrayantennas:spatialambiguitiesexist1234567……1234567……Vectorantenna:noambiguitiesforDOAestimationVectorantennasVs.phasedarrayantennasDisadvantagesofvectorantennasCheap?

Canusehardwareandsoftwareofexisting

communicationsystemsforperformance?f=2.4GHz,=0.125m;vectorantennasize:0.0125m~0.063mPhasedarray:d/2=0.063m;L=(N-1)d:0.188m-0.69m(N=4…12)f=800MHz,=0.375m;antennasize:0.04m~0.19mPhasedarray:d/2=0.19m;L=(N-1)d:0.56m-2.06m(N=4…12)Lowprofile?

source:M.R.Andrewsetal.,Nature,Vol.409(6818),18Jan.2001,pp316-318.

Workinginscatteringenvironment2-dipole(monopole)Lowprofileantennaswithpolarizationdiversity(c)dipole-loop(b)2-loopTDD/TDMAPacketswitchingAAP1AP2userHandoffbetweenApswasnotstandardizedatthesametimeas802.11bPacketswitching:3beamsystemtopview(horizontal)P.Sanchis,etal.02AnindoorWLANdesignA4-storyofficebuilding(includingbasement),high30m,wide60mandlong100m.WeplantoinstallaVivatoswitchedarrayonthe3rdfloor.L=100mh=30mw=60mSwitchedarray321BasementAnindoorWLANdesignDatarate1Mbps,2Mbps,5.5Mbps,11MbpsAP’sEIEP44dBmAP’santennaGainGA25dBiPCantennaGainGP0dBiShadowing8dBAP’santennareceivingsensitivitySmin-95dBm,-92dBm,,-89dBm,-86dBmAP’sNoisefloor-178dBm/HzBody/orientationloss2dBSoftpartitionattenuatefactor(p=number)p1.39dBConcrete-wallattenuatefactor(q=number)q2.38dBAveragefloorattenuation(floornumber)14.0dB(1),19.0dB(2),23.0dB(3),26.0dB(4)Frequency2.4GHzReferencepathlossPL0(LOS/NLS,r=1m)45.9dB/50.3dBPathlossexponent(LOS/NLS,r=1m)2.1/3.0Pathlossstandarddeviation(LOS/NLS)2.3dB/4.1dBAveragefloorattenuation(floornumber)14.0dB(1),19.0dB(2),23.0dB(3),26.0dB(4)DataofAP’santennaisfromAnindoorWLANdesignMeanpathlosswithsmin:Pathlossmodel:Thecoveragerangesare:r=36m,29m,23mand18mfordaterateat1Mbps,2Mbps,5.5Mbpsand11Mbpsrespectively

Allowablepathloss:Case1:userisonthe3rdfloor:3concretewalls,3softpartitionsThecoveragerangesare:r=176m,140m,111mand88mfordaterateat1Mbps,2Mbps,5.5Mbpsand11Mbpsrespectively.Case2:userisinthebasement:3floors;2concretewalls,3softpartitionsBeamformingantennasinadhocnetworksP.GuptaandP.R.Kumar,00throughputobtainedbyeachnodeBeam-formingantennas?newroutingprotocolnewchannelaccessschemeBeamformingantennasinadhocnetworksinterferencetargetPhasedpatchantennaD.LuandD.Rutledge,Caltech,02Z0=50Z0=50,L/2Z0=25,L/2SeriesresonantpatcharrayPhasedpatcharrayBeamformingantennasinadhocnetworksMediumAccessControlProtocol(CSMA/CA)CSMA/CA:carriersensemultipleaccess/collisionavoidance(foromnidirectionalantennas)(Scheduled/On-demand)PacketroutingNeighbordiscoveryNostandardMACprotocolsfordirectionalantennaAdhocnetworksmayachievebetterperformanceinsomecasesusingbeamformingantennas.Noobviousimprovementforthroughputusingbeamformingantennas

Neighbordiscoverybecomemorecomplexusingbeamformingantennas.

Beamformingantennascansignificantlyincreasingnodeandnetworklifetimeinadhocnetworks.1)traditionalexposednodeproblemforomnidirectionalantennasChannelaccessSource:YKoetal.,00ABCDERTSCTSDATAACKRTSCTSDATADATADATAACKABCDERTSCTSCTSDATADATAACKRTSCTSCTSDATADATAACK1)Nocoveragechan