Citation

Abstract

Communication channels where bandwidth efficiency is a prime concern suffer from interference (crosstalk), the principal performance-limiting impairment in many communications systems. Interference arises where communications systems lie in close proximity and it has two forms: co-channel interference and adjacent-channel interference. In twisted-pair subscriber loops, interference is in the form of co-channel interference. In radio channels, as in satellite, microwave, indoor wireless and digital cellular systems, it is in the form of co-channel and adjacent-channel interference. In these systems where the communication is digital, the baud rate clocks are similar, the systems use similar modulation techniques such as PAM, QAM or PSK, and there are only a few dominant or phase-aligned interferers, then the power of the interference can vary with period equal to the baud period, hence the term cyclostationary interference.

In this report, the linear equalizer receiver is analysed under the criterion of minimizing the mean square error in the presence multiple cyclostationary interferers and additive white noise. Furthermore this situation is compared to the case where the mean power spectrum of the interference is the same, but stationary. In order to provide more understanding of the analysis, a pedagogical example is presented. Some preliminary analysis for the zero-forcing and decision-feedback equalizer is also presented. Finally in the context of a subscriber loop system application the performance of the linear equalizer in the presence of cyclostationary interference and stationary noise is compared.