beamforming antennas(波束形成天线)

1、Beamforming Antennas for Wireless Communications Yikun Huang, Ph.D.ECE/CCBYNovember 24 2003OutlinePhased Array AntennasVector AntennasBeamforming antennas for WLANConclusionIntroductionBeamforming and its applicationsBeamforming antennas vs. omnidirectional antennas Direction of a

2、rrival (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

3、modeAn 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

4、 communicationsImagingUltrasonic; 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.

5、 Buckley, University of Michigan, “Beamforming: A Versatile approach to spatial filtering”,1988Applications of beamforming technologyPhased array RADARPhased array spike sorting0 .1 3 90 .5 4 4Ey 1 nt()1 .21 040t0 .0 5 60 .2 0 5Ey 2 nt()1 .21 040t0.0420.187Ey3nt()1.21040tSortedSpike of individual ne

6、urons.123416567891415131211100.1390.534Rn3t()1.21040t0.1830.539Rn5t()1.21040t0.1470.534Rn7t()1.21040t0.1470.534Rn9t()1.21040t0.1830.539Rn11t()1.21040t0.1390.534Rn13t()1.21040t0.140.534Rn1t()1.21040t0.1480.534Rn15t()1.21040tNeuronal spikes recorded by electrode arrayPhased array spike sorting systemC

7、enter for Computational Biology, MSUPatterns, beamwidth & Gain Isotropic dipoletop view(horizontal)side view(vertical)half-wave dipolebeamformer21/Half-power beam widthHalf-power beam widthHalf-power beam widthMain lobeside lobesnulls21/78Beamformers vs. omnidirectional antennas1)Beamformers hav

8、e much higher Gain than omnidirectional antennas: Increase coverage and reduce number of antennas!Gain:21NGGN0306090120150180210240270300330642069.961 107Field 6 0()Field 2 0()Field 1 0()Beamformers vs. omnidirectional antennas2) Beamformers can reject interference while omnidirectional antennas can

9、t: Improve SNR and system capacity! 3) Beamformers directionally send down link information to the users while omnidirectional antennas cant: save energy!userinterferenceuserinterferencenullBeamformers vs. omnidirectional antennasuserusernullmultipath4) Beamformers provide N-fold diversity Gain of o

10、mnidirectional antennas: increase system capacity(SDMA)5) Beamformers suppress delay spread:improve signal qualityDOA estimationkddkkksinsin2phase delay1234567NN-2N-1N-3 dkkdsinkPlane waveBeamformingphase shifters1234567NN-2N-1N-3 k 1,k2,k3,k4,k5,k6,k7,kN-3,kN-2,kN-1,kN,k)sin)(,kdNkkN1phased array (

11、fixed/adaptive) configurations-time domainBasic phased array configurationsNarrowbandsN(k)s2(k)s1(k).w*Nw*2w*1)(kybroadbandsN(k)s2(k)s1(k).)(kyw*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-1phased array (fixed/adaptive) configuration-frequency domainBasic phased array config

12、urationssN(k)s2(k)s1(k).-+IFFTMSEFFTw*Nw*2w*1)(ky)(tdFFTFFTFFTbroadband.Smart antenna systemsMilitary networks Cellularcommunicationnetworks Wireless local area networks switched array adaptive arrayswitched array adaptive arrayswitched array adaptive arrayWi-Fi Data rate:11Mbps3G Data rate:100kbpsS

13、witched array (predetermined)top view(horizontal)Smart antenna systemsinterferenceuser 12345678910111213141516user 1Interference 1top view(horizontal)user 2Smart antenna systems Interference 2Adaptive array Smart antenna 12100 In door range(Mixed Office) 11 Mbps: up to 300m5.5 Mbps: up to 400m 2 Mbp

14、s: up to 500m 1 Mbps: up to 600m Out 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 to 4.20km5.5 Mbps: up to 5.10km 2 Mbps: up to 6.00km 1 Mbps: up to 7.20kmActive user per switch100Examp

15、le: Vivato 2.4 GHz indoor & outdoor Wi-Fi Switches (EIRP=44dBm;Gain=25 dBi;3-beam)PolarizationcircularElinear=0EEellipse=45XYZ iE jieE sinEicos EE=90ESuperCART Compact array radiolocation technologyFlam&Russell,Inc.,1990U.S. Patent No., 5,300,885;1994Frequency range: 2 30 MHzSuper CART3-loop

16、V6V4V3V1V2V5YX LeZIV)0(0LeZIV)(iHz0IiEy0Ikb0.5b2-loopHESSteering vectoracosesinsincoscossinsincoscossinhheejzxzy00000004HiiE001222zyxeee1222zyxhhhBlind pointVector antennas vs. spatial array antennasVector antennas measure: , and power simultaneously, no phase shift device, or synchronization is nee

17、ded. Phased array antennas with omnidirectional 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 2211ffsinsin1234567 kk1234567 1

18、2P,h,h,h,e,e,ezyxzyxVector antenna: no ambiguities for DOA estimationVector antennas 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

19、=0.063m;L=(N-1)d: 0.188m-0.69m(N=412)f=800MHz, =0.375m; antenna size: 0.04m 0.19mPhased array: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

20、 with polarization diversity(c) dipole-loop(b) 2-loopTDD/TDMAPacket switchingAAP1AP2userHandoff between Aps was not standardized at the same time as 802.11bPacket switching: 3 beam systemtop view(horizontal)iiiPPPd11P. Sanchis, et al. 02iP1iP1iP1221121221ddddddiiiDOA ),/(/ ),/( ),/(/maxmaxmaxAn indo

21、or 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=60mSwitched array321BasementAn indoor WLAN designData rate1Mbps, 2Mbps, 5.5Mbps, 11MbpsAPs EIEP44dBmAPs antenna Gain GA25 dBiPC a

22、ntenna Gain GP0 dBiShadowing8dBAPs antenna receiving sensitivity Smin-95dBm ,-92dBm, ,-89dBm, -86dBmAPs Noise floor-178dBm/HzBody/orientation loss2dBSoft partition attenuate factor (p= number)p1.39 dBConcrete-wall attenuate factor(q= number)q2.38 dBAverage floor attenuation(floor number)14.0dB(1),19

23、.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 attenuation(floor number)14.0dB(1),19.0dB(2),23.0dB(3),26.0dB(4)Data of APs antenna is from An indoor WL

24、AN designMean pathloss with smin:PGSEIRPLminosdflsmwallowableLLLLLLPL Path loss model:)log()(0010rrPLrPLalPLrPL)(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 the 3rd floor: 3 concrete walls, 3 soft

25、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,00throughput obtained by each node

26、nnlogWBeam-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/2 Z0=25,L/2Series resonant patch arrayPhased patch arrayBeamforming antennas in ad hoc networksMedium Acce

27、ss 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 using beamforming

28、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 omnidirectional antennasChannel accessSource:Y Ko et al., 00ABCDERTSCTSDATAACKRTSCTSDATADATADATAACKABCDERTSCT