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Introduction to Smart Antenna. Advisor : Dr. Wen-Jye Huang Student : Chi-Ting Wu 2004.08.18 Wireless Communication LAB. OUTLINE. Introduction What is Smart Antenna ? Why Smart Antenna ? How Smart Antenna works ? ULA UCA Conclusion. Introduction. Rapid growth of wireless communication - PowerPoint PPT Presentation
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Introduction to Smart Introduction to Smart AntennaAntenna
AdvisorAdvisor :: Dr. Wen-Jye HuangDr. Wen-Jye Huang
StudentStudent :: Chi-Ting WuChi-Ting Wu
2004.08.182004.08.18
Wireless Communication LABWireless Communication LAB
OUTLINEOUTLINE
► IntroductionIntroduction►What is Smart Antenna ?What is Smart Antenna ?►Why Smart Antenna ?Why Smart Antenna ?►How Smart Antenna works ?How Smart Antenna works ?
ULAULA UCAUCA
►ConclusionConclusion
IntroductionIntroduction
► Rapid growth of wireless communicationRapid growth of wireless communication► Multi-services requirementMulti-services requirement► Effective usage of frequency bandEffective usage of frequency band► Classic antennas are omni-directionalClassic antennas are omni-directional
smart antennasmart antenna
What is Smart AntennaWhat is Smart Antenna
► Concept of SDMA systemConcept of SDMA system► Arrange in a particular geometric formArrange in a particular geometric form► Use few methods to change EM wave patternUse few methods to change EM wave pattern
Switched beam systemSwitched beam system Adaptive antenna systemAdaptive antenna system
Switched beam systemSwitched beam system
。 select one of several beams to enhance received signals
Adaptive antenna systemAdaptive 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 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 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► 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
►UUniformniform L Linearinear A Arrayrray geometry geometry►UUniformniform C Circularircular A Arrayrray geometry 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
ConclusionConclusion
► Smart Antenna offer new ways to combat and/or exploit the spatial channel
► Smart Antennas reduce co-channel Smart Antennas reduce co-channel interference, improve BER performance and interference, improve BER performance and hence capacityhence capacity