The Journal of Korean Institute of Communications and Information Sciences (한국통신학회논문지)

The Korean Institute of Commucations and Information Sciences (한국통신학회)
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Impact of Multipath Fading on the Performance of the DDLMS Based Spatio Temporal Smart Antenna

다중경로페이딩이 DDLMS 기반 스마트 안테나의 성능에 미치는 영향

  • 홍영진 (동명대학교 전기전자공학과)
  • Published : 2009.09.30
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Abstract

The performance variations of a spatio temporal smart antenna which is equipped at the basestation of CDMA cellular communication network due to the parametric change of multipath fading environment are studied in this paper. The smart antenna of interest employs space diversity based adaptive array structure in conjunction with rake receiver that has fingers the number of which is the same as that of multipath links. The beamforming is achieved via LMS(Least Mean Square) algorithm in which a reference signal is generated using decision directed formula. It has been shown by computer simulation that the performance of our smart antenna of interest depends significantly upon not only the degree of desired signal's DOA(Direction of Arrival)spread but the number of fingers of the rake receiver. The relative insensitivity of the smart antenna's performance on desired signal's delay spread has also been observed. Computer simulation has shown that the increase of the number of fingers brings in a nonlinear enhancement of the performance of our smart antenna. The renewal of weight vector in the beamforming procedure is taken place at post PN despread stage.

본 논문에서는 코드분할다중접속(CDMA)시스템의 기지국에 설치할 수 있는 시공간 배열 스마트안테나의 성능이 다중경로 환경의 다양한 파라미터의 변화에 어떻게 반응하는지 살펴보았다. 이 논문에서 사용된 스마트안테나는 공간분산구조로 적응배열안테나를, 시간분산구조로 다중경로의 숫자에 따른 finger 의 레이크 수신기로 구성되었으며 빔형성 방법으로 Decision Directed LMS 방법을 사용한다. 스마트안테나는 다중경로 신호의 입사각분산의 정도와 다중경로(finger)의 숫자에 민감하게 반응하는 한편 지연분산의 정도와는 거의 반응하지 않음이 컴퓨터 모의실험으로 증명되었다. 레이크 수신기의 핑거 숫자의 증가가 스마트안테나의 성능을 비선행적으로 개선시키는 효과를 수반함 역시 모의실험으로 보여졌다. 본 논문의 빔형성 과정에서 가중치벡터의 갱신은 PN상관기가 수신신호를 역확산시킨 후에 이루어진다.

Keywords

References

  1. A. M. Viterbi and A. J. Viterbi, 'Erlang capacity of a power controlled CDMA system,' IEEE J. Select. Areas Commun., vol. 11, no. 6, pp. 892-900, Aug. 1993 https://doi.org/10.1109/49.232298
  2. E. Dahlman, P. Beming, J. Knutsson, F. Ovesjo, M. Persson, and C. Roobol, 'WCDMA - The radio interface for future mobile multimedia communications,' IEEE Trans. Veh. Technol., vol. 47, pp. 1105-1118, Nov. 1998 https://doi.org/10.1109/25.728481
  3. M. Zeng, A. Annamalai, and V. Bhargava, 'Recent advances in cellular wireless communications,' IEEE Commun. Mag. (Special Issue on Wideband CDMA), vol. 36, pp. 128- 138, Sep. 1999
  4. D. Kim and D. Sung, "Capacity estimation for an SIR-based power controlled CDMA system supporting on-off traffic," IEEE Trans. Veh. Technol., vol. 50, no. 3, pp. 1094-1101, July 2000 https://doi.org/10.1109/25.875216
  5. A. Naguib, 'Adaptive antennas for CDMA wireless networks,' Ph.D. dissertation, Stanford Univ., 1996
  6. S. Choi and D. Yun, 'Design of an adaptive antenna array for tracking the source of maximum power and its application to CDMA mobile communications,' IEEE Trans. Antennas Propagat. vol. 45, pp. 1393-1404, Sep.1997 https://doi.org/10.1109/8.623129
  7. J. Winters, 'Smart antennas for wireless systems,' IEEE Personal Commun. Mag., pp. 23-27, Feb. 1998
  8. 홍영진, 'CDMA 상향채널용 CGM-LMS 접목적응빔형성 알고리듬에 관한 연구,' 한국통신학회논문지 vol. 32, no. 9, pp. 895-904, Sep. 2007
  9. J. Liberti and T. Rappaport, 'Reverse channel performance improvements in CDMA cellular communication systems employing adaptive antennas,' IEEE Proc. Globecom, vol. VI, pp. 42-47, 1993
  10. C. Gardner and J. Orr, 'Fading effects on the performance of a spread spectrum multipleaccess communication system,' IEEE Trans. Commun., vol. COM-27, pp. 143-149, Jan. 1979 https://doi.org/10.1109/TCOM.1979.1094256
  11. G. Turin, 'The effects of multipath and fading on the performance of direct-sequence CDMA systems,' IEEE J. Select. Areas Commun., vol. SAC-2, no. 4, pp. 597-603, July 1984 https://doi.org/10.1109/JSAC.1984.1146087
  12. T. Ottosson and M. Skoglund, 'Joint source channel and multiuser decoding for Rayleigh fading CDMA channels,' IEEE Trans. Commun., vol. 48 no. 1, pp. 13-16, Jan. 2000 https://doi.org/10.1109/26.818867
  13. A. Higashi and T. Matsumoto, 'Combined adaptive RAKE diversity(ARD) and coding for DPSK DS/CDMA mobile radio,' IEEE J. Select. Areas Commun., vol. 11, pp. 1076-1084, Sep. 1993 https://doi.org/10.1109/49.233220
  14. A. Naguib and A. Paulraj, 'Performance of CDMA cellular networks with base-station antenna arrays,' Proc. International Zurich seminar on digital communications, pp. 87-100, Mar. 1994
  15. S. Durrani, and M. Bialkowski, 'The performance of a smart antenna system in multipath fading environment for CDMA,' Proc. Fourth Australian Communications Theory Workshop Melbourne, pp. 10-10, Feb. 2003
  16. F.Ueng, J. Chen, and S. Cheng, 'Smart antennas for multiuser DS/CDMA communications in multipath fading channels,' Proc. ISSSAT2004, pp. 400-404, Aug. 2004
  17. C. Ng, and et. al., 'Directional diversity of smart antenna in LAS CDMA systems,' Wireless Personal Communications, vol. 46 no. 3, pp. 305-316, Aug. 2008 https://doi.org/10.1007/s11277-007-9435-4