A Family of Selective-Tap Algorithms for Stereo Acoustic Echo Cancellation

Abstract

The use of adaptive lters employing tap-selection for stereophonic acoustic echo cancellation is investigated. We propose to employ subsampling of the tap-input vector, that is intrinsic to partial update schemes, to improve the conditioning of the tap-input autocorrelation matrix hence improving convergence. We investigate the effect of MMax tap-selection on the convergence rate for the single channel case by proposing a new measure which is then used as an optimization parameter in the development of our tapselection scheme in the two channel case. The resultant exclusive maximum tap-selection is then applied to two channel NLMS, AP and RLS algorithms. Although our main motivation is not the reduction of complexity of SAEC, the proposed tap-selection nevertheless brings signicant computation savings in additional to an improved rate of convergence over algorithms using only a nonlinear preprocessor.

Selective-Tap Adaptive Filtering With Performance Analysis for Identification of Time-Varying Systems

“…3, for , increases smoothly and consequently the degradation in steady-state performance is negligible. This property has been exploited in the exclusive-maximum (XM) tap selection, which has been deployed in SAEC algorithms to give good convergence performance such as presented in [13] and [14]. In addition, we have shown that under time-varying unknown system conditions, there exists for NLMS and MMax-NLMS, an optimal step-size given by (29) and (56), respectively, which jointly maximizes the performances in terms of low misalignment and high convergence rate.…”

“…It has been shown in [13] that the performance of MMax-NLMS degrades only gracefully with reducing compared to fully updated NLMS. For , the degradation in performance can be insignificant.…”

“…The exclusive-maximum (XM) tap selection criterion addresses the ill-conditioning of the SAEC problem by selecting taps for updating so as to maximize jointly the -norm of the selected taps over both channels subject to the exclusivity constraint that taps with the same index may not be selected in both channels. In [13] and [14], partial updating based on the XM tap selection criterion was shown to give good convergence performance for SAEC applications and has motivated the current analytical study of the convergence behavior of selective-tap algorithms.…”

Efficient multichannel acoustic echo cancellation using constrained tap selection schemes in the subband domain

“…The number of taps selected in the sub-filterĤ r (k, ) is finally determined by substituting (26) in (19).…”

“…The most common approach to tackle the misalignment problem is to decorrelate the tap-inputs, for which several techniques have been proposed in literature [3,15,17]. Tap selection schemes such as the exclusive-maximum (XM) [18][19][20] have also been proposed to specifically tackle the misalignment problem for stereo AEC applications. The XM scheme improves the conditioning of the tap-input covariance matrix via exclusive updates of the two adaptive filters, i.e., in each iteration the same filter tap index is never selected in both channels.…”