Design of totally multiplier-less sharp transition width tree structured filter banks for non-uniform discrete multitone system

In this paper, a multiplier-less near perfect reconstruction tree structured non-uniform filter bank for discrete multitone (DMT) system is proposed. In DMT systems, filters with sharp transition width are required to reduce the inter-channel interference. When sharp transition width filter banks are to be implemented, the order of the filters will become very high. Frequency response masking technique is known to result in filters with sharp transition width with less complexity. To further reduce the complexity and power consumption, the filter bank is made totally multiplier-less by converting the continuous filter coefficients to finite precision coefficients in the canonic signed digit space. This may lead to performance degradation and calls for the use of suitable optimization techniques. Here, the search space consists of only integers. Hence, meta-heuristic algorithms are preferred as they can be tailor made to suit the problem under consideration. In this work, meta-heuristic algorithms such as, artificial bee colony, harmony search and gravitational search are deployed to improve the performance of the tree structured filter bank. Thus, the proposed method results in tree structured non-uniform filter banks which are simple, multiplier-less and have linear phase, sharp transition width, very low aliasing and reduced amplitude distortion.