Smart Antenna (1)

Smart AntennaSmart AntennaRashmikanta DashRashmikanta DashRegd.no:0601209202Regd.no:0601209202ETC-A-52ETC-A-52

OUTLINEOUTLINEIntroductionWhat is Smart Antenna ?Why Smart Antenna ?How Smart Antenna works ?

◦ULA◦UCA

Conclusion

IntroductionIntroductionRapid growth of wireless

communicationMulti-services requirementEffective usage of frequency bandClassic antennas are omni-directional

smart antenna

What is Smart Antenna ?What is Smart Antenna ?

Concept of SDMA systemArrange in a particular geometric formUse few methods to change EM wave pattern

◦ Switched beam system◦ Adaptive antenna system

Switched beam systemSwitched beam system

。 select one of several beams to enhance received signals

Adaptive antenna Adaptive antenna systemsystem

。 adaptive beam system can adjust its antenna pattern to enhance the desired signal

。 null or reduce interference

。 collect correlated multipath power

Why Smart AntennaWhy Smart Antenna

Higher capacity (traffic/area)Better transmission quality and/or

coverage

Standard Coverage

Extended Coverage

Why Smart AntennaWhy Smart Antenna

Reduction of transmitter powerReduction of delay spreadAccurate user position estimation

Fixed cell shape Dynamic cell shape

Limiting effects of the wireless channelMulti-path propagation gives rise to

fading inter-symbol interference time variation of signals

Co-channel interference gives rise to increased noise level and hence greater

errors

Multi-path propagationMultipath components

suffer different delaysThis gives rise to ISI reject or stimulate

multipath components by changing their radiation patterns

significantly reduce the requirements of equalization and/or increase CINR

Mobile

Smart Antenna

LoS

MP

Co-channel interference

Interference from other directions than wanted user

suppress unwanted user by placing nulls in directions of unwanted signals

improved transmission quality and/or system capacity

Mobile 2

Smart Antenna

LoS

MPMobile 1

Interference

How Smart Antenna worksHow Smart Antenna works

Uniform Linear Array geometryUniform Circular Array geometry

UUniformniform L Linearinear A Arrayrray geometrygeometry

cos ( 1) cos( ) ( ) 1 .....Tjkd j L kd

ULAa g e e

( 1) 0T

lr l d

1

( ) ( ) ( )M

m mm

t s t

x aBase-band signal

UUniformniform C Circularircular A Arrayrray geometrygeometry

2 ( 1) 2 ( 1)cos sin

T

l

l lR

L L

r

(0, ) (1, ) ( 1, )( ) ( ) .....Tj j j L

UCAa g e e e

2 ( 1) 2 ( 1)( , ) cos cos sin sin

l ll kR

L L

1( ) ( )....... ( )T

Mt s t s ts

( ) ( ) ( ) ( )t t t X A s n

1( ) ( .... ( ) ( )M L x M A a a

1

( ) ( ) ( )M

m mm

t t

x a s

ConclusionConclusionSmart Antenna offer new ways to

combat and/or exploit the spatial channel

Smart Antennas reduce co-channel interference, improve BER performance and hence capacity

THANK YOU……………..THANK YOU……………..