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Introduction to Smart Antenna

Introduction to Smart Antenna

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Introduction to Smart Antenna

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  1. Introduction to Smart Antenna Advisor:Dr. Wen-Jye Huang Student:Chi-Ting Wu 2004.08.18 Wireless Communication LAB

  2. OUTLINE • Introduction • What is Smart Antenna ? • Why Smart Antenna ? • How Smart Antenna works ? • ULA • UCA • Conclusion

  3. Introduction • Rapid growth of wireless communication • Multi-services requirement • Effective usage of frequency band • Classic antennas are omni-directional smart antenna

  4. 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

  5. Switched beam system 。select one of several beams to enhance received signals

  6. Adaptive antenna system 。adaptive beam system can adjust its antenna pattern to enhance the desired signal 。null or reduce interference 。collect correlated multipath power

  7. Why Smart Antenna • Higher capacity (traffic/area) • Better transmission quality and/or coverage

  8. Why Smart Antenna • Reduction of transmitter power • Reduction of delay spread • Accurate user position estimation Fixed cell shape Dynamic cell shape

  9. 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

  10. 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

  11. 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

  12. How Smart Antenna works • Uniform Linear Array geometry • Uniform Circular Array geometry

  13. Uniform Linear Array geometry

  14. Base-band signal

  15. Uniform Circular Array geometry

  16. 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