New Variable Step-size LMS Algorithm with Low-Pass Filtering of Instantaneous Gradient Estimate

순시 기울기 벡터의 저주파 필터링을 사용한 새로운 가변 적응 인자 LMS 알고리즘

  • 박장식 (동의공업대학 영상정보과) ;
  • 문건락 ((주)금영 부설연구소 연구원) ;
  • 손경식 (부산대학교 전자공학과)
  • Published : 2001.06.01

Abstract

Adaptive filters are widely used for acoustic echo canceler, adaptive equalizer and adaptive noise canceler. Coefficients of adaptive filters are updated by NLMS algorithm. However, Coefficients are misaligned by ambient noises when they are adapted by NLMS algorithm. In this Paper, a method determined the adaptation constant by low-pass filtered instantaneous gradient vector of LMS algorithm using orthognality principles of optimal filter is proposed. At initial states, instantaneous gradient vector, that is the cross-correlation of input signals and estimation error signals, has large value because input signals are remained in estimation error signals. When an adaptive filter is conversed, the cross-correlation will be close to zero. It isn's affected by ambient noises because ambient noises are uncorrelated with input signals. Determining adaptation constant with the cross-correlation, adaptive filters can be robust to ambient noises and the convergence rate doesn't slower As results of computer simulations, it is shown that the performance of proposed algorithm is betted than that of conventional algorithms.

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