A new method of channel shortening with applications to discrete multi-tone (DMT) systems

Abstract

A new procedure is proposed for solving the problem of channel shortening (a.k.a. the TEQ problem) for discrete multi tone (DMT) systems. Channel shortening is accomplished by using an multi-input-single-output (MISO) adaptive filter bank at the receiver. Each input represents a "logical path" from the transmitter to the receiver The "paths" are derived either via oversampling, or by using multiple analog to digital converters (A/Ds) with different sampling delays, or from A/Ds connected to different receive antennas (as may be the case in a wireless system). It is shown that for a finite order linear time invariant channel, it is always possible (provided certain conditions are met) to find a FIR filter bank combiner such that the effective length of the channel is no more than the cyclic prefix.