On Delayless Architecture for the Normalized Subband Adaptive Filter

Delayless architecture for the recently proposed normalized subband adaptive filter (NSAF) is described and analyzed in this paper. The NSAF has a unique weight-control mechanism whereby error signals estimated in subbands are used to adapt a fullband filter. In the delayless architecture, we implement the subband weight adaptation in an auxiliary loop, and place only the fullband filter along the input signal path. By so doing, delay due to the filter banks is moved to the auxiliary loop out of the signal path, thereby making the algorithm attractive for applications where excessive signal path delay is intolerable. Simulation results demonstrate that the proposed delayless NSAF outperforms other delayless approaches in terms of convergence rate.