Prototype filter design for oversampled subband adaptive filtering structures

In this paper, the design of prototype filters for uniform DFT filter banks used in oversampled subband adaptive filtering structures is investigated. Two optimization procedures (a linear and a nonlinear) are proposed for the search of the optimal coefficients of the analysis and synthesis prototype filters. The nonlinear method is based on the minimization of an estimate of the steady-state mean-square error, while the linear approach uses the results of a convergence analysis to design the analysis prototype filter and then finds the synthesis prototype filter by a LMS-type algorithm. Computer simulation results are presented to illustrate the improvements in the convergence characteristics of the oversampled subband structure obtained with the proposed prototype design methods