Polyphase based adaptive structure for adaptive filtering and tracking

An asymptotically alias-free parallel structure for adaptive filtering applications is considered. The structure promotes the polyphase implementation of a sampling frequency filter bank. Using accumulators in each band as post-filters, the scheme forms a zooming mechanism on alias-free points in the frequency domain. This implies that the bands would become asymptotically uncorrelated which allows independent adaptations in each subband. If sufficient number of bands are used and the input is rich enough, perfect identification of unknown FIR systems is achieved, both analytically and experimentally. The effectiveness of this method in identifying long impulse responses, especially under adverse input coloring and changing environment, makes this structure a viable alternative to available methods. With theoretically proven convergence behavior, this method outperforms the LMS and RLS type algorithms in many cases, some of which are presented in the paper