Inherent decorrelating and least perturbation properties of the normalized subband adaptive filter

This correspondence describes and analyzes a class of subband adaptive filters (SAFs) that stems from various approaches of applying subband and multirate techniques in adaptive filtering. This class of SAFs, called the normalized SAF (NSAF), has a unique weight-control mechanism, whereby subband error signals are used to adapt a fullband tap-weight vector. In this correspondence, we elaborate on the inherent decorrelating properties of the NSAF, which manifest themselves in different forms as integral elements of the weight-control mechanism. We also show that the NSAF possesses some least perturbation properties that are also found in the normalized least-mean-square (NLMS) and affine projection (AP) algorithms.