Selective-tap adaptive algorithms in the solution of the nonuniqueness problem for stereophonic acoustic echo cancellation

Abstract

Abstract-We investigate stereophonic acoustic echo cancellation in which solutions for the system can be nonunique and propose the use of selective-tap adaptive filters to address this problem. The main concept is to employ tap selection to optimize jointly for minimum interchannel coherence and maximum -norm of the subselected tap-input vectors. The exclusive maximum (XM) tap-selection approach is proposed and applied to normalized least-mean squares (NLMS) and recursive least-squares (RLS) algorithm. We propose an approach for solving the nonuniqueness problem employing XM tap selection in combination with a nonlinear preprocessor. Simulation results show a significant improvement in convergence rate compared with existing techniques.Index Terms-Adaptive filtering, selective-tap, stereophonic acoustic echo cancellation.

Affine projection and recursive least squares adaptive filters employing partial updates

“…The error signal is given by e n = d n −ĥ T n x n . It has been shown in [6] that the reduction in convergence rate due to tap-selection can be explained by introducing a measure M n , as the ratio of the energy of the M selected tap-inputs to the energy of all the tap-inputs in the tap-input vector such that…”

“…We rst note that direct application of MMax tap-selection will not serve to decorrelate the two tap-input vectors x 1,n and x 2,n because, since they are highly correlated, nearly identical tap-indices will be selected in both lters. We thus propose the use of an extended version of our tap-selection schemes to jointly maximize the MMax criterion whilst minimizing inter-channel coherence by imposing an exclusivity constraint [6]. The resulting exclusive maximum (XM) tap-selection algorithm employs M = 0.5L and achieves the reduction in interchannel coherence by selecting exclusive tap-inputs such that, at each iteration, selection of the same tap index in both channels is not permitted.…”

“…An efcient approximate sort [5] has been proposed which reduces this cost. Whereas for a single channel case, partial updating schemes are motivated by the reduction in computational complexity, these algorithms have recently been employed successfully in the area of stereophonic acoustic echo cancellation (SAEC) [6] to achieve interchannel decorrelation. It has been shown that for realistic applications, the high interchannel coherence between the two channels results in an ill-conditioned autocorrelation matrix of the tap-input vectors [7].…”

Survey of Sparse Adaptive Filters for Acoustic Echo Cancellation

“…These include Variable step size (VSS) algorithms, [2] [3] [4] partial update adaptive filtering techniques [5][6] and sub-band adaptive filtering (SAF) techniques. [7] These approaches aim to address the issues in echo cancellation including the performance with colored input signals and time varying echo paths and a computational complexity to name but a few.…”

A Class of Sparseness-Controlled Algorithms for Echo Cancellation

“…These include Fourier [3] and wavelet [4] based adaptive algorithms, variable step-size (VSS) algorithms [5]- [7], data reusing techniques [8], [9], partial update adaptive filtering techniques [10], [11] and subband adaptive filtering (SAF) schemes [12]. These approaches aim to address issues in echo cancellation including the performance with colored input signals, time-varying echo paths and computational complexity, to name but a few.…”