Journal of the Institute of Electronics Engineers of Korea TC (대한전자공학회논문지TC)

The Institute of Electronics and Information Engineers (대한전자공학회)
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Adaptive Feedback Interference Cancellation Using Correlations for WCDMA Wireless Repeaters

WCDMA용 무선중계기에서 상관도를 이용한 적응적 궤환 간섭 제거

  • Moon, Woo-Sik (School of Electronic Engineering, Soongsil University) ;
  • Im, Sung-Bin (School of Electronic Engineering, Soongsil University) ;
  • Kim, Chong-Hoon (School of Electronic Engineering, Soongsil University)
  • 문우식 (숭실대학교 정보통신전자공학부) ;
  • 임성빈 (숭실대학교 정보통신전자공학부) ;
  • 김종훈 (숭실대학교 정보통신전자공학부)
  • Published : 2007.07.25
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Abstract

As the mobile communication service is widely used and the demand for wireless repeaters is rapidly increasing because of the easiness of extending service areas. But a wireless repeater has a problem that the output of the transmit antenna is partially fed back to the receive antenna, which results in feedback interference. In this paper, we propose a new varable step-size LMS algorithm which utilizes correlation between reference and error signals to adjust the step sizes, for cancelling the feedback interference signals in the WCDMA repeater under time-varying multi-path channels. The proposed algorithm was evaluated through computer simualation by being applied to the feedback canceling filter of the WCDMA repeater. The simulation results demonstrated that the proposed one is superior to the conventional ones in terms of the cancelation perormance.

최근 이동통신 서비스가 광범위하게 사용되고 서비스 영역의 용이한 확대로 인하여 무선중계기에 대한 수요가 급격히 증가하고 있다. 그러나 무선중계기에는 중계된 전송 신호의 일부가 궤환되어 다시 수신안테나에 수신되는 궤환 간섭 신호가 발생한다. 궤환 간섭 신호의 제거에 이용하는 LMS (Least Mean Square) 알고리즘은 연산량이 적어 실시간으로 적용할 수 있지만, 필터 계수를 갱신에 일정한 스텝 사이즈(step size)를 사용하여 시변 채널과 같은 상황에서 성능이 저하된다. 이런 문제를 해결하기 위하여 본 논문에서는 궤환 간섭 제거기의 참조 입력 (reference input)과 에러 신호 사이에서 상관도를 구하여, 스텝 사이즈를 조정하는 새로운 가변 스텝 사이즈 LMS 알고리즘을 제안한다. 제안된 알고리즘을 WCDMA 무선 중계기에서 궤환 간섭 신호를 제거하는 필터에 적용하여 모의실험을 하였고, 기존의 간섭 제거 알고리즘과 비교하여 성능이 우수함을 확인할 수 있었다.

Keywords

References

  1. Lu Youhong and M. Morris Joel, 'GABOR EXPANSION for Adaptive Echo Cancellation,' IEEE Siganal Processing Magazine, Vol. 16, Issue 2, pp. 68-80, Mar. 1999 https://doi.org/10.1109/79.752052
  2. Chi-Chou Kao, 'Design of echo cancellation and noise elimination for speech enhancement,' IEEE Transactions on Consumer Electronics, Vol. 49, Issue 4, pp. 1468-1473, Nov. 2003 https://doi.org/10.1109/TCE.2003.1261255
  3. A. K. Kohli and D. K. Mehra, 'Trackin of time-varying channels using two-step LMS-type adaptive algorithm,' IEEE Transactions on Signal Processing, Vol. 54, Issue 7, pp. 2606-2615, July 2006 https://doi.org/10.1109/TSP.2006.874779
  4. W. G. Jeon and Y. S. Cho, 'An equalization technique for OFDM and MC-CDMA in a multipath fading channels,' in Proc. of IEEE Conf. on Acoustics, Speech and Signal Processing, pp. 2529-2532, Munich, Germany, May 1997
  5. Y. K. Won, R.-H. Park, J. H. Park and B.-U. Lee, 'Variable LMS algorithms using the time constant concept,' IEEE Transactions on Consumer Electronics, Vol. 40, Issue 3, pp.655-661, Aug. 1994 https://doi.org/10.1109/30.320854
  6. M. R. Asharif and T. Hayashi, 'Correlation LMS for Double- Echo Cancelling,' Proceeding of the IASTED International Conference, Modelling and Simulation(MS'99), Philadelphia, PA(Cherry Hill New Jersey) USA, pp. 249-253, May 1999
  7. M. R. Asharif, T. Hayashi, K. Yamashita, 'Correlation LMS algorithm and its application to double-talk echo cancelling,' IEEE Electronics Letters, Vol. 35, Issue 3, pp. 194-195, Feb. 1999 https://doi.org/10.1049/el:19990151