beamingantennas(波束形成天线)课件

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1、Beamforming Antennas for Wireless CommunicationsYikun Huang,Ph.D.ECE/CCBYikuncns.montana.eduNovember 24 2003OutlinePhased Array Antennas Vector Antennas Beamforming antennas for WLANConclusionIntroductionBeamforming and its applicationsBeamforming antennas vs.omnidirectional antennas Direction of ar

2、rival(DOA)estimationBeamformingBasic configurations:fixed array and adaptive arraysmart antenna systems:switched array and adaptive arrayDOA and polarizationsuper CART3-loop and 2-loop vector antenna arrayDirection of arrival(DOA)estimationVector antenna vs.phased array antennaInfrastructure modeAn

3、indoor WLAN designAd hoc modeAd hoc WLAN for rural areaApplicationsDescriptionRADARPhased array RADAR;air traffic control;synthetic aperture RADARSONARSource location and classificationCommunicationsSmart antenna systems;Directional transmission and reception;sector broadcast in satellite communicat

4、ionsImagingUltrasonic;optical;tomographicGeophysical ExplorationEarth crust mapping;oil explorationAstrophysical ExplorationHigh resolution imaging of universeBiomedicalNeuronal spike discrimination;fetal heart monitoring;tissue hyperthermia;hearing aidsSource:B.D.Van Veen and K.M.Buckley,University

5、 of Michigan,“Beamforming:A Versatile approach to spatial filtering”,1988Applications of beamforming technologyPhased array RADARPhased array spike sortingSortedSpike of individual neurons.12341656789141513121110Neuronal spikes recorded by electrode arrayPhased array spike sorting systemCenter for C

6、omputational Biology,MSUPatterns,beamwidth&Gain Isotropic dipoletop view(horizontal)side view(vertical)half-wave dipolebeamformerHalf-power beam widthHalf-power beam widthHalf-power beam widthMainlobesidelobesnulls78Beamformers vs.omnidirectional antennas1)Beamformers have much higher Gain than omni

7、directional antennas:Increase coverage and reduce number of antennas!Gain:Beamformers vs.omnidirectional antennas2)Beamformers can reject interference while omnidirectional antennas cant:Improve SNR and system capacity!3)Beamformers directionally send down link information to the users while omnidir

8、ectional antennas cant:save energy!userinterferenceuserinterferencenullBeamformers vs.omnidirectional antennasuserusernullmultipath4)Beamformers provide N-fold diversity Gain of omnidirectional antennas:increase system capacity(SDMA)5)Beamformers suppress delay spread:improve signal qualityDOA estim

9、ationphase delay1234567NN-2N-1N-3dPlane waveBeamformingphase shifters1234567NN-2N-1N-31,k2,k3,k4,k5,k6,k7,kN-3,kN-2,kN-1,kN,kphased array(fixed/adaptive)configurations-time domainBasic phased array configurationsNarrowbandsN(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,

10、0w*2,1w*2,k-1.Z-1Z-1w*1,0w*1,1w*1,k-1.Z-1Z-1phased array(fixed/adaptive)configuration-frequency domainBasic phased array configurationssN(k)s2(k)s1(k).-+IFFTMSEFFTw*Nw*2w*1FFTFFTFFTbroadband.Smart antenna systemsMilitary networksCellularcommunicationnetworks Wireless local area networksswitched arra

11、y adaptive arrayswitched array adaptive arrayswitched array adaptive arrayWi-Fi Data rate:11Mbps3G Data rate:100kbpsSwitched array(predetermined)top view(horizontal)Smart antenna systemsinterferenceuser 12345678910111213141516user 1Interference 1top view(horizontal)user 2Smart antenna systems Interf

12、erence 2Adaptive array Smart antenna 12100In door range(Mixed Office)11 Mbps:up to 300m5.5 Mbps:up to 400m 2 Mbps:up to 500m 1 Mbps:up to 600mOut door range(outdoor to indoor)11 Mbps:up to 1.00km5.5 Mbps:up to 1.25km 2 Mbps:up to 2.00km 1 Mbps:up to 2.50kmOut door range(outdoor to outdoor)11 Mbps:up

13、 to 4.20km5.5 Mbps:up to 5.10km 2 Mbps:up to 6.00km 1 Mbps:up to 7.20kmActive user per switch100Example:Vivato 2.4 GHz indoor&outdoor Wi-Fi Switches(EIRP=44dBm;Gain=25 dBi;3-beam)PolarizationcircularElinear=0EEellipse=45XYZ EE=90ESuperCART Compact array radiolocation technologyFlam&Russell,Inc.,1990

14、U.S.Patent No.,5,300,885;1994Frequency range:2 30 MHzSuper CART3-loopV6V4V3V1V2V5YX kb0.5b2-loopHESSteering vectorBlind pointVector antennas vs.spatial array antennasVector antennas measure:,and power simultaneously,no phase shift device,or synchronization is needed.Phased array antennas with omnidi

15、rectional element measure:,and powerSource:Nehorai,A.,University of Illinois at ChicagoVector antennas vs.spatial array antennasVASAVASAVector antennas vs.spatial array antennasPhased array antennas:spatial ambiguities exist 12345671234567Vector antenna:no ambiguities for DOA estimationVector antenn

16、as Vs.phased array antennasDisadvantages of vector antennasCheap?Can use hardware and software of existing communication systems for performance?f=2.4GHz,=0.125m;vector antenna size:0.0125m 0.063mPhased array:d/2=0.063m;L=(N-1)d:0.188m-0.69m(N=412)f=800MHz,=0.375m;antenna size:0.04m 0.19mPhased arra

17、y:d/2=0.19m;L=(N-1)d:0.56m-2.06m(N=412)Low profile?source:M.R.Andrews et al.,Nature,Vol.409(6818),18 Jan.2001,pp 316-318.Working in scattering environment(a)2-dipole(monopole)Low profile antennas with polarization diversity(c)dipole-loop(b)2-loopTDD/TDMAPacket switchingAAP1AP2userHandoff between Aps

18、 was not standardized at the same time as 802.11bPacket switching:3 beam systemtop view(horizontal)P.Sanchis,et al.02An indoor WLAN designA 4-story office building(including basement),high 30 m,wide 60m and long 100m.We plan to install a Vivato switched array on the 3rd floor.L=100mh=30mw=60mSwitche

19、d array321BasementAn indoor WLAN designData rate1Mbps,2Mbps,5.5Mbps,11MbpsAPs EIEP44dBmAPs antenna Gain GA25 dBiPC antenna Gain GP0 dBiShadowing8dBAPs antenna receiving sensitivity Smin-95dBm,-92dBm,-89dBm,-86dBmAPs Noise floor-178dBm/HzBody/orientation loss2dBSoft partition attenuate factor(p=numbe

20、r)p1.39 dBConcrete-wall attenuate factor(q=number)q2.38 dBAverage floor attenuation(floor number)14.0dB(1),19.0dB(2),23.0dB(3),26.0dB(4)Frequency2.4GHzReference pathloss PL0(LOS/NLS,r=1m)45.9dB/50.3dBPathloss exponent (LOS/NLS,r=1m)2.1/3.0Pathloss standard deviation (LOS/NLS)2.3dB/4.1dBAverage floor

21、 attenuation(floor number)14.0dB(1),19.0dB(2),23.0dB(3),26.0dB(4)Data of APs antenna is from An indoor WLAN designMean pathloss with smin:Path loss model:The coverage ranges are:r=36m,29m,23m and 18m for date rate at 1Mbps,2Mbps,5.5Mbps and 11Mbps respectively Allowable pathloss:Case 1:user is on th

22、e 3rd floor:3 concrete walls,3 soft partitionsThe coverage ranges are:r=176m,140m,111m and 88m for date rate at 1Mbps,2Mbps,5.5Mbps and 11Mbps respectively.Case 2:user is in the basement:3 floors;2 concrete walls,3 soft partitionsBeamforming antennas in ad hoc networksP.Gupta and P.R.Kumar,00through

23、put obtained by each nodeBeam-forming antennas?new routing protocol new channel access schemeBeamforming antennas in ad hoc networksinterferencetargetPhased patch antennaD.Lu and D.Rutledge,Caltech,02Z0=50Z0=50,L/2Z0=25,L/2Series resonant patch arrayPhased patch arrayBeamforming antennas in ad hoc n

24、etworksMedium Access Control Protocol(CSMA/CA)CSMA/CA:carrier sense multiple access/collision avoidance(for omnidirectional antennas)(Scheduled/On-demand)Packet routingNeighbor discovery No standard MAC protocols for directional antenna Ad hoc networks may achieve better performance in some cases us

25、ing beamforming antennas.No obvious improvement for throughput using beamforming antennas Neighbor discovery become more complex using beamforming antennas.Beamforming antennas can significantly increasing node and network lifetime in ad hoc networks.1)traditional exposed node problem for omnidirect

26、ional antennasChannel accessSource:Y Ko et al.,00ABCDERTSCTSDATAACKRTSCTSDATADATADATAACKABCDERTSCTSCTSDATADATAACKRTSCTSCTSDATADATAACK1)No coverage change.May save power.2)B may not know the location of C.The nodes are prohibit to transmit or receive signalsThe node is free to transmit or receive sig

27、nalsThe node is blocked to communicate with C2)Omnidirectional and directional antennas solve the exposed node problemChannel accessABCDERTSCTSCTSDATARTScollisiondeafcollisionABCDERTSCTSDATADATARTS3)beamforming antennas create new problemsNeighbor discoveryABCDEAtNt“Hello”APNeighborsAB,CBA,CCA,B,EDE

28、EC,DAd hoc WLAN for rural areaConclusionBeamforming antenna systems improve wireless network performance -increase system capacity-improve signal quality -suppress interference and noise -save powerBeamforming antennas improve infrastructure networks performance.They may improve ad hoc networks performance.New MAC protocol standards are needed.Vector antennas may replace spatial arrays to further improve beamforming performance