Complexity reduction of partial update oversampled subband adaptive algorithms by selective pruning of polyphase components

Partial update algorithms such as sequential LMS have been proposed to reduce computation cost. To further decrease the computation cost for low-resource real-time echo cancellation by oversampled subband adaptive filters (OS-SAFs), we propose a new hybrid partial update algorithm. This algorithm, based on a polyphase perspective, selectively prunes (zeros out) polyphase components of the adaptive filter. When employed on OS-SAFs, the proposed algorithm achieves significant complexity reduction. This algorithm is applied to sequential versions of LMS and pseudo-affine projection algorithms employed to adapt OS-SAFs. Presented performance evaluations prove that considerable computation cost reduction (typically more than four times) is feasible with practically insignificant degradations in the steady-state performance of the OS-SAF system. Moreover, the algorithm does not affect initial convergence properties.