The Journal of Korean Institute of Information Technology (한국정보기술학회논문지)

Korean Institute of Information Technology (한국정보기술학회)
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An Algorithm for Variable Step-Size Improving Steady-State Performance of Blind Equalization

블라인드 등화의 정상상태 성능개선을 위한 수렴상수 가변 알고리즘

  • 오길남 (광주대학교 광통신공학과)
  • Published : 2011.10.31
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Abstract

For blind equalization algorithms with excellent convergence characteristics, the steady-state performance is not the case. In this paper, for blind equalization, as a way to solve the problems of the methods commonly used to improve the steady-state performance, a scheme for variable step-size is proposed. In the proposed approach, as the equalizer converges to steady-state, the step-size is varied, and is decreased consistently as iteration proceeds in the steady-state. The proposed algorithm has improved the steady-state performance of the equalizer without compromising the initial convergence characteristics of the equalizer. The proposed method, applied to the algorithms with good blind convergence characteristics, is fit to improve the steady-state performance as well as making it easier to be combined with other algorithms by improving its steady-state performance. The proposed idea is applied to the constant modulus algorithm (CMA), then its performance improvement is confirmed under multipath propagation channel and higher-order QAM constellations.

블라인드 수렴 특성이 우수한 등화 알고리즘의 경우 정상상태 성능은 그렇지 못하다. 본 논문에서는 블라인드 등화에서 정상상태 성능을 개선하는데 흔히 사용되는 방법들의 문제점을 해결하기 위해 수렴상수를 가변하는 방법을 제안한다. 제안 방식에서는 등화기가 정상상태로 수렴함에 따라 수렴상수를 가변하였으며, 정상상태에서 등화가 진행될수록 수렴상수가 지속적으로 줄어들도록 하여 등화기의 초기 수렴 특성을 저해하지 않으면서 정상상태 성능을 개선하였다. 제안 방식은 블라인드 수렴 특성이 좋은 알고리즘에 적용하여 정상상태 성능을 개선하는데 적합할 뿐만 아니라, 정상상태 성능을 개선함으로써 다른 알고리즘과의 결합을 더욱 용이하게 한다. 제안 아이디어를 CMA에 적용하여 다중경로 전파 채널 하에서 고차 QAM에 대한 성능 개선 효과를 검증하였다.

Keywords

References

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