An adaptive, multirate method for eliminating intersymbol interference in non-ideal channel.

Abstract

In this thesis, an adaptive method for eliminating intersymbol interference (ISI) using multirate techniques, is presented. This is inspired by the work of Chevillat and Ungerboeck on the design of finite impulse response (FIR) 'multirate zero ISI filters' for data transmission over a band limited ideal channel. Their analysis is extended to the case when the channel is non-ideal. It is shown that there are infinitely many multi rate filters (dependent of the upsampling/downsampling factor Mc) that can eliminate ISI. As an illustration, two simple adaptive algorithms for computing the zero ISI filters are presented and applied to discrete multitone transmission (DMT) and discrete wavelet multitone transmission (DWMT) systems. It is found that even the minimum length, multirate zero ISI filters compare favourably (in terms of reduced complexity and performance) with other techniques, such as the cyclic prefix method.