Suppression of adjacent-channel interference in digital radio by equalization

Abstract

In this paper, the ability of a linear or decisionfeedback equalizer to suppress adjacent-channel interference in digital radio is described. The emphasis is on values among transmitter bandwidth, receiver bandwidth, carrier spacing, diversity, and co-channel interference which provide the best opportunities for interference suppression. Through analysis of a generalized zero-forcing linear equalizer and calculations of equalizer minimum-mean-square performance, it is shown that a substantial amount of adjacent-channel interference can be suppressed. Furthermore, the ability to suppress the interference is enhanced by using equalizers with wide receiver bandwidths because they are able to exploit the cyclostationary properties of the adjacent-channel interference.