A new adaptive subband structure with critical sampling

In this paper, a new adaptive subband structure with critical sampling of the subband signals, which yields exact modeling of FIR systems, is derived. An adaptation algorithm, which minimizes the sum of the subband squared-errors, is obtained for the updating of the coefficients of the new subband structure, resulting in significant convergence rate improvement for colored input signals when compared to the full-band LMS algorithm. A simplified version of the adaptation algorithm, with reduced computational complexity, is also presented. An efficient implementation of the proposed subband structure is described, with computational savings of the order of the number of subbands when compared to the full-band LMS. Computer simulations illustrate the convergence behavior of the proposed algorithms