Optimum linear diversity receivers for mobile communications

This paper analyzes and quantifies the performance of a space diversity combining receiver operating in a mobile radio environment with quaternary phase-shift-keying transmission, frequency-selective Rayleigh multipath fading, and cochannel interference (CCI). The receiver has an infinite-length filter in each branch of the diversity combiner, and the filters are optimized jointly according to the minimum mean-square-error criterion. The link bit error rate is estimated accurately using Metzger´s (1987) algorithm, which approximates the probability density function of the combined intersymbol interference (ISI) and CCI. The authors present numerical performance results showing the influence of the diversity order, the number of dominant cochannel interferers, the multipath channel´s delay spectrum, and the root-mean-square delay spread. The results show that, under certain conditions, the optimum linear receiver can almost completely eliminate all ISI and CCI while providing near-optimum noise filtering