Subband acoustic echo cancellation using a thin lattice structure

In this paper a novel subband acoustic echo canceller (AEC) is proposed. The proposed scheme consists in K non-overlapping main subbands and K auxiliary subbands implemented using DFT filter bank approach. The auxiliary subbands are introduced in order to provide frequency coverage in the non-overlapping region between the neighboring main subbands. Central to computational efficiency of the proposed scheme is the decimation of the auxiliary bands by a factor of 2 relative to the main bands. A gradient lattice structure, known as thin lattice with predictor part of considerably smaller size than its ladder (filtering) part, is utilized to adapt the taps of subband adaptive filter in the main and auxiliary bands. Simulation results for K=9 number of bands attest to superior tracking and echo attenuation of the proposed structure.