The Journal of the Institute of Internet, Broadcasting and Communication (한국인터넷방송통신학회논문지)

The Institute of Internet, Broadcasting and Communication (한국인터넷방송통신학회)
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The Performance improvement of CMA Blind Adaptive equalizer using the Constellation Matching Method

Constellation Matching 기법을 이용한 CMA 블라인드 적응 등화기의 성능 개선

  • 임승각 (공주대학교 정보통신공학부) ;
  • 강대수 (공주대학교 정보통신공학부)
  • Received : 2010.01.20
  • Published : 2010.02.28
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Abstract

This paper relates with the improved CMA blind adaptive equalization algorithm which uses the constellation matching method that improve the inverse modelling efficiency of a communication channel compared to the present CMA blind adaptive equalizer. The amplitude distortion can be compensated in the present CMA blind adaptive equalizer which is used for the reduction of intersymbol interference by distortion that generate such as a band limited wireless mobile channel, but in the improved adaptive alogorithm operates with the minimize the amplitude phase distortion in the output of equalizer by applying the cost function that is composition of additional signal constellation matching error terms. In order to evaluation of the inverse modeling efficiency of improved algorithm, the residual intersymbol interference and recovered signal constellation were compared by computer simulation. As a result of comparion of computer simulation, the improved algorithm has a good stability in the residual intersymbol interference in the steady state, but it has a slow convergence rate in the adaptation state in initial state.

본 논문에서는 기존의 CMA 블라인드 적응 등화기의 통신 채널 역모델링 성능을 개선시킬 수 있는 Constellation Matching 기법을 적용한 개선된 CMA 블라인드 적응 알고리즘에 대한 것이다. 무선 이동 채널과 같은 대역 제한 채널에서 발생되는 찌그러짐에 의한 부호간 간섭 영향을 줄이기 위하여 사용되던 기존의 CMA 블라인드 적응 등화기에서는 진폭 찌그러짐을 보상하는 반면 개선된 적응 알고리즘에서는 부가적인 신호 constellation matching (CM) 오차항을 포함하는 비용 함수를 적용하여 등화기 출력에서 진폭과 위상 찌그러짐을 최소화하도록 동작한다. 개선 알고리즘의 역모델링의 성능을 평가하기위하여 컴퓨터 시뮬레이션을 통해 잔여 부호간 간섭양과 복원된 신호의 constellation 을 기존 방식과 비교하였다. 시뮬레이션 결과 제안된 방식이 기존 방식보다 정상 상태에서 안정된 잔여 부호간 간섭양을 얻을 수 있었지만 수렴 속도에서 초기의 적응 과정에서 늦어짐을 확인하였다.

Keywords

References

  1. Ta-Hsin Li, Kais Mbarek, "A Blind Equalizer for nonstationary Discrete-Valued Signals", IEEE Trans. on Signal Processing, pp.247-254, Vol.45, No.1, Jan. 1997 https://doi.org/10.1109/78.552224
  2. S. Barbarossa, A.Scaglione, "Blind equalization using cost functions matched to the signal constellation", Proc. 31st Asilomar Conf. Signal Syst. Comput., Packfic Grove, CA, Nov. 1997
  3. Lin He, G.Amin, C.Reed, C.Malkemes, "A Hybrid Adaptive Blind Equalization Algorithm for QAM Signals in Wireless Communications", IEEE Trans. on Signal Processing, pp.2058-2069, Vol.52, No.7, July 2004 https://doi.org/10.1109/TSP.2004.828913
  4. Y.Chen, Tho Le-Ngoc, B.Champagne, C.Xu, "Recursive Least Squares Constant Modulus Algorithms for Blind Adaptive Array", IEEE Trans. on Signal Processing, pp.1452-1456, Vol.52, No.5, May 2004 https://doi.org/10.1109/TSP.2004.826167
  5. V.Zarzoso, P.Comon, "Optimal Step-Size Constant Modulus Algorithm", IEEE Trans. on Comm., pp.10-13, Vol.56, No.1, Jan. 2008 https://doi.org/10.1109/TCOMM.2008.050484
  6. I.Fijalkow, A.Touzni, J.Treichler, "Fractionaalspaced equalization with CMA : Roburstness to channel noise and lack of disparity", IEEE Trans. on Signal Processing, Vol.45, pp.56-66, Jan. 1997 https://doi.org/10.1109/78.552205
  7. T.E.Biedka, W.H.Tranter, J.H.Reed, "Convergence analysis of the least squares constant modulus algorithm in interference cancellation applications", IEEE Trans. on Signal Processing, Vol.48, pp.491-501, Mar. 2000
  8. 이종현, 임승각, "OFDMA 기반 Wibro 중계국에서 루프 간섭 제거 및 적응 등화기를 이용한 성능 개선에 관한 연구", 제43권, TC편, 제11호, pp.1402-1409, 2006
  9. Lin He, Saleem A.Kassam, "Convergence analysis of bline equalization algorithms using constellation-matching", IEEE Trans. on Comm., Vol.56, No.11, Nov. 2008
  10. S.Haykin, Adaptive Filter Theory, 2nd Edition, Prentice Hall, 1991
  11. A.L.Sayed, Fundamentals of Adaptive Filtering, Wiley-Interscience, 2003