190 likes | 531 Views
Introduction to Smart Antenna. 指導老師:黃文傑 博士 姓 名: 吳 濟 廷 2003.11.07 無線通訊實驗室. 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
E N D
Introduction to Smart Antenna 指導老師:黃文傑 博士 姓 名: 吳 濟 廷 2003.11.07 無線通訊實驗室
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
Why Smart Antenna • Higher capacity (traffic/area) • Better transmission quality and/or 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
Smart Antenna LoS MP Mobile 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
Smart Antenna Interference LoS MP Mobile 2 Mobile 1 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
How Smart Antenna works • Wave propagation • Parametric data model • Uniform Linear Array geometry • Uniform Circular Array geometry
Wave propagation • From Maxwell’s equations • Homogeneous wave equation • f satisfy homogeneous wave equation
Parametric data model Base-band signal Array propagation vector
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