Fullband error adaptation of subband adaptive filters

Abstract

For many years now, subband and frequency-domain adaptive filtering techniques have been proposed for the identification of high-order FIR systems. Standard fullband algorithms are less attractive as the implementation cost is higher and their convergence behaviour is typically worse. Subband processing has many desirable properties. However, when used to implement adaptive filters, various side effects occur which reduce the performance. On the other hand, frequency-domain adaptive filters, such as the PBFDAF, do not suffer from these problems despite being (nearly) equivalent to subband adaptive filters, be it with poor filter banks. An alternative fullband error based adaptation scheme for subband adaptive systems is proposed. It is shown that the weight updating mechanism of the so-called unconstrained PBFDAF is closely related to the proposed fullband error adaptation algorithm.