A Recursive Method for the Approximation of LTI Systems Using Subband Processing

Using the subband technique, an LTI system can be implemented by the composition of an analysis filterbank, followed by a transfer matrix (subband model) and a synthesis filterbank. The advantage of this approach is that it offers a good tradeoff between latency and computational complexity. In this paper we propose an optimization method for approximating an LTI system using the subband technique. The proposed method includes optimal allocation of parameters from different FIR entries of the subband model, while keeping constant the total number of parameters, for a better utilization of the available coefficients. The optimization is done in a weighted least-squares sense considering either linear or logarithmic amplitude scale. Simulation results demonstrate the advantages of the proposed method when compared with classical implementation approaches using pole-zero transfer functions or segmented FFT algorithms.