The Journal of the Acoustical Society of Korea (한국음향학회지)

The Acoustical Society of Korea (한국음향학회)
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A Constant Modulus Algorithm (CMA) for Blind Acoustic Communication Channel Equalization with Improved Convergence Using Switching between Projected CMA and Algebraic Step Size CMA

직교 정사영 CMA와 대수학적 스텝 사이즈 CMA 간 스위칭 방법을 통해 개선된 수렴성을 갖는 CMA형 블라인드 음향 통신 채널 등화기 연구

  • 임준석 (세종대학교 전자정보통신공학과) ;
  • 편용국 (강원도립대학 정보통신공학과)
  • Received : 2015.06.05
  • Accepted : 2015.07.27
  • Published : 2015.09.30
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Abstract

CMA (Constant Modulus Algorithm) is one of the well-known algorithms in blind acoustic channel equalization. Generally, CMA converges slowly and the speed of convergence is dependent on a step-size in the CMA procedure. Many researches have tried to speed up the convergence speed by applying a variable step-size to CMA, e.g. the orthogonal projection CMA and algebraic optimal step-size CMA. In this paper, we summarize these two algorithms, and we propose a new CMA with improved convergence performance. The improvement comes from the switching between the orthogonal projection CMA and algebraic optimal step-size CMA. In simulation results, we show the performance improvement in the time invariant channels as well as in time varying channel.

음향 통신용 등화기 기술 중에서, 훈련 신호를 사용하지 않는 블라인드 채널 등화기의 일종인 Constant Modulus Algorithm(CMA)방식 등화기의 수렴 속도는 일반적인 훈련 신호를 사용하는 비블라인드 방법에 비해서 느린 경향이 있다. 이런 느린 수렴 속도를 향상 시키기 위한 방법으로는 직교 정사영 망각인자를 도입한 직교 정사영 CMA와 대수적인 방법으로 스텝 사이즈를 계산하는 대수학적 스텝 사이즈 CMA 등이 제안되어 있다. 이들 두 방법 모두 수렴 속도를 향상시키지만 경우에 따라서 성능이 기대에 못 미치는 결과가 발생하기도 한다. 본 논문에서는 직교 정사영 CMA와 대수학적 스텝 사이즈 CMA를 각각 요약 설명 하고, 이 각각을 스위칭을 이용하여 결합하는 방법을 제안한다. 그리고 시뮬레이션을 통해서 여러 시불변 채널과 시변 채널에 대해서 그 수렴 성능이 개선됨을 보인다.

Keywords

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