Subband adaptive filtering decimation constraints for oversampled nonuniform filterbanks

Abstract

To avoid significant inband aliasing, the decimation factors for a real filterbank must satisfy strict constraints. These decimation constraints decrease the real filterbank's computational efficiency by requiring higher subband data rates. To combat this, a set of modified pseudo-quadrature mirror filter equations are proposed which easily construct complex near-perfect reconstruction filterbanks that can be utilized to build both uniform and nonuniform filterbanks with no significant inband aliasing. With a properly designed real or complex filterbank, subband adaptive filters illustrate low m.s.e. after convergence. However, the computational complexity and convergence time associated with the complex filterbank is significantly less. Several numerical simulations are included to illustrate the conclusions.