Smart Antenna (1)

Smart Antenna Rashmikanta Dash Regd.no:0601209202 ETC-A-52

OUTLINE Introduction What

is Smart Antenna ? Why Smart Antenna ? How Smart Antenna works ? ◦ ULA ◦ UCA Conclusion

Introduction Rapid

growth of wireless communication Multi-services requirement Effective usage of frequency band Classic antennas are omni-directional



smart antenna

What is Smart Antenna ? Concept

of SDMA system Arrange in a particular geometric form Use few methods to change EM wave pattern ◦ Switched beam system ◦ Adaptive antenna system

Switched beam system

。 select one of several beams to enhance received signals

Adaptive antenna system

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

null or reduce interference

。 collect correlated multipath power

Why Smart Antenna Higher

capacity (traffic/area) Better transmission quality and/or coverage

Standard Coverage

Extended Coverage

Why Smart Antenna  Reduction

of transmitter power  Reduction of delay spread  Accurate user position estimation

Fixed cell shape

Dynamic cell shape

Limiting effects of the wireless channel Multi-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 propagation  Multipath

components suffer different delays  This gives rise to ISI Smart Antenna  reject or stimulate multipath components by changing their radiation patterns  significantly reduce the requirements of equalization and/or increase CINR

LoS MP

Mobile

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

Smart Antenna Mobile 2 LoS MP

Interference

Mobile 1

How Smart Antenna works Uniform

Linear Array geometry Uniform Circular Array geometry

Uniform Linear Array geometry

rl = [ (l − 1)d 0]

T

aULA ( )  g ( )  1 e

 jkd cos

.....e

M

Base-band signal

 j ( L 1) kd cos

x(t ) = ∑ a(θ m ) sm (t ) m =1



T

Uniform Circular Array geometry

2π (l − 1)  rl = R cos L 

2π (l − 1)  sin  L

T

 2π ( l − 1)  2π ( l − 1) ϕ ( l , θ ) = kR  cos cosθ + sin sin θ   L L 

aUCA ( )  g ( )  e

 j (0, )

e

 j (1, )

..... e

 j ( L 1, ) T



M

x(t ) = ∑ a m (θ )s m (t ) m =1

s(t ) = [ s1 (t ).......sM (t )]

T

A(θ ) = [ a(θ 1....a(θ M )] ( L x M )

X(t ) = A(θ )s(t ) + n(t )

Conclusion Smart

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……………..