On the Performance of Multiuser Switched Diversity Systems with Co-channel Interference

We investigate the effect of co-channel interference on the performance of multiuser switched diversity (MUSwiD) systems. In such systems, the first checked user whose channel quality is greater than a predetermined switching threshold is assigned the system resources and allowed to conduct its uplink transmission. In this paper, we derive closed-form expressions for the end-to-end outage probability and symbol error probability (SEP) for the independent non-identically distributed and independent identically distributed cases of desired users channels. In the analysis, all system links are assumed to follow Rayleigh distribution with the interference is being considered at the base station. Approximate expressions for the outage probability and SEP are derived in the high signal-to-noise (SNR) regime which allow for an easy evaluation of the system performance. Monte Carlo simulations are provided to validate the derived analytical and asymptotic expressions. Results show that the system can still achieve performance gain when more desired users are available and the interference power is fixed. This happens at the values of switching threshold that are comparable to average SNR. Asymptotic results illustrate that the system has a diversity order of 1 and a coding gain that is affected by several parameters such as the switching threshold, number of interferers, and the outage threshold. Finally, findings show that the MUSwiD user selection scheme is efficient for systems which operate at the range of low SNR values and this makes it an attractive candidate to be implemented in the emerging mobile broadband communication systems.