Performance of BPSK and QPSK over the nonselective Rayleigh fading channels with maximal ratio combining and multiple asynchronous cochannel interferers

In this paper we investigate the performance of coherent PSK modulation with maximal ratio combining, in nonselective Rayleigh fading channels with multiple asynchronous cochannel interferers. Exact BEP results for BPSK and QPSK are derived. Moreover, for a system using rectangular pulse shaping filter, the effect of the symbol timing offset between the desired signal and the interfering signals on the error performance is analytically studied. Our results reveal that the impairment due to cochannel interference is maximized when all users are synchronized, and minimized when all interfering signals are half symbol duration delayed with respect to the desired signal. Based on these findings, explicit and simple closed-form results are obtained as the upper and lower bounds of the BEP.