Multi-plet two-channel perfect reconstruction filter banks

This paper proposes a new class of two-channel structural perfect reconstruction (PR) FIR filter banks (FB) called the multi-plet FB. It generalizes structural PR FB proposed by Phoong et al. (1995) and triplet FB by employing multiple lifting steps similar to the conventional lifting structure. Apart from the important structural PR property, the multi-plet FB can be systematically designed to meet a given specification on the passband/stopband ripples and transition bandwidth. A low order prototype PR FB with a much wider transition band is first designed in order to obtain prescribed passband and stopband ripples. A subfilter is then designed so that the prototype FB can be wrapped by means of frequency transformation to meet the desired transition bandwidth, while preserving the PR condition, passband/stopband ripples and lifting structure. The design procedure is very general and it can be applied to both linear-phase and low-delay multi-plet FB. Design examples show that the proposed approach is more flexible in controlling the frequency characteristics of the PR FB and has a lower design complexity than conventional methods.