beam forming antennas

8/2/2019 Beam Forming Antennas

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Beamforming Antennas for

Wireless Communications

Yikun Huang, Ph.D.

ECE/CCB

[email protected]

November 24 2003


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Outline

Phased Array Antennas

Vector Antennas

Beamforming antennas for WLAN

Conclusion

Introduction

Beamforming and its applicationsBeamforming antennas vs. omnidirectional antennas

Direction of arrival (DOA) estimationBeamformingBasic configurations: fixed array and adaptive array

smart antenna systems:switched array and adaptive array

DOA and polarizationsuper CART3-loop and 2-loop vector antenna arrayDirection of arrival (DOA) estimationVector antenna vs. phased array antenna

Infrastructure modeAn indoor WLAN designAd hoc modeAd hoc WLAN for rural area


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Applications Description

RADAR Phased array RADAR; air traffic control; synthetic apertureRADAR

SONAR Source location and classification

Communications Smart antenna systems; Directional transmission andreception; sector broadcast in satellite communications

Imaging Ultrasonic; optical; tomographic

Geophysical Exploration Earth crust mapping; oil exploration

Astrophysical Exploration High resolution imaging of universe

Biomedical Neuronal spike discrimination; fetal heart monitoring;tissue hyperthermia; hearing aids

Source: B.D.Van Veen and K.M. Buckley, University of Michigan, Beamforming: A

Versatile approach to spatial filtering,1988

Applications of beamforming technology


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Phased array RADAR
http://www.nssl.noaa.gov/rrdd/par/parimages/images/PAR_Dome4.jpg


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Phased array spike sorting

0.139

0.544

E y1 n t( )

1 . 2 1 040 t

0.056

0.205

E y2 n t( )

1 . 2 1 04

0 t

0.042

0.187

Ey3n t( )

1 .2 1 04

0 t

Sorted

Spike of

individual

neurons.

1

2

3

4

1 6

5

6

7

8

9

1 4

1 5

1 3

1 2

1 1

1 0

0.139

0.534

R n 3 t( )

1.2 104

0 t

0.183

0.539

R n 5 t( )

1.2 104

0 t

0.147

0.534

R n 7 t( )

1.2 104

0 t

0.147

0.534

R n 9 t( )

1.2 104

0 t

0.183

0.539

R n 11 t( )

1.2 104

0 t

0.139

0.534

R n 13 t( )

1 .2 1 04

0 t

0.14

0.534

R n 1 t( )

1 . 2 1 04

0 t

0.148

0.534

Rn 1 5 t( )

1 . 2 1 04

0 t

Neuronal

spikesrecorded by

electrodearray

Phasedarrayspikeso

rtingsystem

Center for Computational Biology, MSU


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Patterns, beamwidth & Gain

Isotropic dipole

topview(horizontal)

sideview(vertical)

half-wave dipole beamformer

21/

Half-power

beam width

Half-powerbeam width

Half-powerbeam width

Main lobe

side lobes

nulls

21/78


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Beamformers vs. omnidirectional antennas

1) Beamformers have much higher Gain than omnidirectional antennas:Increase coverage and reduce number of antennas!

Gain:2

1

NG

GN

0

30

60

90

120

150

180

210

240

270

300

330

6

4

2

0

6

9.961 107

Field 6 0 ( )

Field 2 0 ( )

Field 1 0 ( )


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2) Beamformers can reject interference while omnidirectionalantennas cant: Improve SNRand system capacity!

3) Beamformers directionally send down link information to theusers while omnidirectional antennas cant: save energy!

user

interference

user

interferencenull


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user user

null

multipath

4) Beamformers provide N-fold diversity Gain of omnidirectional antennas:increase system capacity(SDMA)

5) Beamformers suppress delay spread:improve signal quality


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DOA estimation

kd

dkkk sinsin

2

phase delay

1 2 3 4 5 6 7 NN-2 N-1N-3

d

kk d sin

k

Plane wave


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Beamforming

phase shifters

1 2 3 4 5 6 7 NN-2 N-1N-3

k

1,,k 2,,k 3,,k 4,,k 5,,k 6,,k 7,,k N-3,,k N-2,,k N-1,,k N,,k

)sin)((

, kdN kkN 1


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phased array (fixed/adaptive) configurations-time domain

Basic phased array configurations

Narrowband

sN(k)

s2(k)

s1(k)

.

.

.

w*N

w*2

w*1

)(ky

broadband

sN(k)

s2(k)

s1(k)

.

.

.

)(ky

w*N,0 w*N,1 w*N,k-1.

.

.

Z-1 Z-1

w*2,0 w*2,1 w*2,k-1.

.

.

Z-1 Z-1

w*1,0 w*1,1 w*1,k-1.

.

.

Z-1 Z-1


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phased array (fixed/adaptive) configuration-frequency domain

Basic phased array configurations

sN(k)

s2(k)

s1(k)

.

.

.

-+

I

F

F

T

MSE

F

F

T

w*N

w*2

w*1

)(ky

)(tdF

FT

F

F

T

F

F

T

broadband

.

.

.


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Smart antenna systems

Military

networks

Cellularcommunication

networks

Wirelesslocal areanetworks

switched arrayadaptive array



Wi-Fi Data rate:11Mbps3G Data rate:100kbps


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Switched array (predetermined)

top view(horizontal)


interference

user

1

2

3

45

6

7

8

9

10

1112 13

14

15

16


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user 1

Interference 1top view(horizontal)

user 2


Interference 2

Adaptive array


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Smart antenna system

www.vivato.net

12

100

In door range(Mixed Office)

11 Mbps: up to 300m5.5 Mbps: up to 400m

2 Mbps: up to 500m1 Mbps: up to 600m

Out door range(outdoor to indoor)

11 Mbps: up to 1.00km

5.5 Mbps: up to 1.25km2 Mbps: up to 2.00km1 Mbps: up to 2.50km

Out door range(outdoor to outdoor)

11 Mbps: up to 4.20km5.5 Mbps: up to 5.10km

2 Mbps: up to 6.00km1 Mbps: up to 7.20km

Active user per switch 100

Example: Vivato 2.4 GHz indoor & outdoor Wi-Fi Switches

(EIRP=44dBm;Gain=25 dBi;3-beam)


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Polarization

circular

E

linear

=0

E

E

ellipse

=45

X

Y

Z

iE

ji eE sin

Eicos

E

E

=90

E


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SuperCARTCompact array radiolocation technology

Flam&Russell,Inc.,1990U.S. Patent No., 5,300,885;1994Frequency range: 2 30 MHz

Super CART


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3-loop

V6

V4

V3

V1 V2

V5

Y

XL

eZIV )0(0

L

eZIV )(

iHz 0

I

iEy 0

Ikb0.5

b


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2-loop

HE

S

Steering vector

a

cos

esin

sincoscossin

sin

coscossin

hh

e

e

j

z

x

z

y

0

0

00

00

0

4

H

ii E00

1222 zyx eee

1222 zyx hhh

Blind point


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Vector antennas vs. spatial array antennas

Vector antennas measure: ,,,,andpower simultaneously,no phase shift device, or synchronization is needed.

Phased array antennas with omnidirectional element measure:

,,andpower


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Source: Nehorai,A.,University of Illinois at Chicago


VA

SA

VA SA


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Phased array antennas: spatial ambiguities exist

2211ff sinsin

1 2 3 4 5 6 7

k

k

1 2 3 4 5 6 7

1

2

P ,,,,h,h,h,e,e,e zyxzyx Vector antenna: no ambiguities for DOA estimation


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Vector antennas Vs. phased array antennas

Disadvantages of vector antennas

Cheap?

Can use hardware and software of existingcommunicationsystems for performance?

f=2.4GHz, =0.125m; vector antenna size: 0.0125m ~ 0.063m

Phased array:d/2=0.063m;L=(N-1)d: 0.188m-0.69m(N=412)

f=800MHz, =0.375m; antenna size: 0.04m ~ 0.19m

Phased array:d/2=0.19m;L=(N-1)d: 0.56m-2.06m(N=412)

Low profile?


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source:M.R. Andrews et al., Nature, Vol. 409(6818), 18 Jan. 2001, pp 316-318.

Working in scattering environment


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(a) 2-dipole(monopole)

Low profile antennas with polarization diversity

(c) dipole-loop

(b) 2-loop


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TDD/TDMA

Packet switching

AAP1 AP2

user

Handoff between Apswas not standardized

at the same time as802.11b


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Packet switching: 3 beam system

top view(horizontal)

i

ii

P

PPd 11

P. Sanchis, et al. 02

iP

1iP

1iP

1221

12

1221

dddd

dd

i

i

i

DOA

),/(/),/(

),/(/

max

max

max


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An indoor WLAN design

A 4-story office building (including basement), high 30 m, wide 60m and long 100m. We planto install a Vivato switched array on the 3rd floor.

L=100m

h=30m

w=60m

Switched array

3

2

1

Basement


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Data rate 1Mbps, 2Mbps, 5.5Mbps, 11Mbps

APs EIEP 44dBm

APs antenna Gain GA 25 dBi

PC antenna Gain GP 0 dBi

Shadowing 8dB

APs antenna receiving sensitivity Smin -95dBm ,-92dBm, ,-89dBm, -86dBm

APs Noise floor -178dBm/Hz

Body/orientation loss 2dB

Soft partition attenuate factor (p= number) p1.39 dB

Concrete-wall attenuate factor(q= number) q2.38 dB

Average floor attenuation(floor number) 14.0dB(1),19.0dB(2),23.0dB(3),26.0dB(4)

Frequency 2.4GHz

Reference pathloss PL0 (LOS/NLS, r=1m) 45.9dB/ 50.3dB

Pathloss exponent (LOS/NLS, r=1m) 2.1/3.0

Pathloss standard deviation (LOS/NLS) 2.3dB/4.1dB

Average floor attenuation(floor number) 14.0dB(1),19.0dB(2),23.0dB(3),26.0dB(4)

Data of APs antenna is from www.vivato.net


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Mean pathloss with smin: PGSEIRPL min

osdflsmwallowable LLLLLLPL

Path loss model: )log()(

0

010

r

rPLrPL

alPLrPL )(

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 partitions

The 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 partitions


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Beamforming antennas in ad hoc networks

P.Gupta and P.R. Kumar,00

throughputo

btained

by

eachn

ode

nnlog

W~

Beam-formingantennas

?

newroutingprotocol

newchannelaccessscheme


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interference

target

Phased patchantenna

D.Lu and D.Rutledge,Caltech,02

Z0=50

Z0=50,L/2 Z0=25,L/2

Series resonant patch array

Phased patch array


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Medium Access Control Protocol(CSMA/CA)CSMA/CA:carrier sense multiple access/collision avoidance( for omnidirectional antennas)

(Scheduled/On-demand)Packet routing

Neighbor discovery

No standard MAC protocols for directional antenna

Ad hoc networks may achieve better performance in some casesusing beamforming antennas.

No obvious improvement for throughput using beamforming antennas

Neighbor discovery become more complex using beamforming antennas.

Beamforming antennas can significantly increasing node andnetwork lifetime in ad hoc networks.


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1) traditional exposed node

problem for omnidirectionalantennas

Channel access

Source:Y Ko et al., 00

A B C D E

RTS

CTSDATA

ACK

RTS

CTS

DATA

DATA

DATA

ACK

A B C D E

RTS

CTS CTS

DATA

DATA

ACK

RTS

CTS CTS

DATA

DATA

ACK

1) No coverage change. May save power.2) B may not know the location of C.

The nodes

areprohibit totransmit orreceivesignals

The nodeis free totransmit orreceivesignals

The node isblocked tocommunicate with C

2) Omnidirectional and

directional antennas solvethe exposed node problem


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Channel access

A B C D E

RTS

CTS

CTS

DATA

RTS

collision

deafcollision

A B C D E

RTS

CTS

DATA

DATA

RTS

3) beamforming antennas create new problems


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Neighbor discovery

AB

C

D

E

A

t

NtHello

AP Neighbors

A B,C

B A,C

C A,B,E

D E

E C,D


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Ad hoc WLAN for rural area


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Conclusion

Beamforming antenna systems improve wireless

network performance-increase system capacity

-improve signal quality

-suppress interference and noise

-save power

Beamforming antennas improve infrastructurenetworks performance. They may improve ad hocnetworks performance. New MAC protocol

standards are needed.Vector antennas may replace spatial arrays to

further improve beamforming performance

beam forming antennas

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