Simple design of oversampled uniform DFT filter banks with applications tosubband acoustic echo cancellation

Subband adaptive filtering, which is the basis of modern acoustic echo canc ellation (AEC) systems, is an important application of filter banks in whic h critical sampling cannot be used in general because of decimation aliasin g effects. This leads to the use of oversampling schemes in the filter bank design wherein the perfect-reconstruction (PR) or near PR property is stil l required. In this work, a simple design technique for uniform DFT filter bank with near PR property is presented for the purpose of subband adaptive filtering. The prototype filter in the proposed filter banks is derived si mply by performing an interpolation of a two-channel QMF filter, which can be obtained easily by computation or table look-up. An efficient implementa tion of the filter banks based on a weighted-overlap-add structure is descr ibed that allows flexibility in oversampling. The filter bank design techni que presented in this paper is of particular interest in engineering applic ations, as demonstrated by design examples and experimental results in a re al-time subband AEC application. (C) 2000 Elsevier Science B.V. All rights reserved.