Outage Analysis of User Scheduling with Antenna Selection in Multiuser Two-Way AF Relaying

We investigate the outage performance of a user scheduling with antenna selection (USAS) scheme for a cellular multiuser two-way relay system over a Rayleigh flat-fading environment. Here, a multi- antenna base station communicates with several mobile users via an amplify-and-forward (AF) relay. The USAS strategy opportunistically selects the best user among multiple users and the best antenna at the base station for bidirectional communication such that the overall system outage probability is minimized. We derive an exact expression for outage probability of the considered scheme that is applicable for all values of signal-to-noise ratio (SNR). To gain better insights and identify key parameters, we present an approximate expression of outage probability in closed-form under a high SNR assumption. Finally, we highlight the impact of antenna selection on the achievable diversity of the considered scheme under various channel conditions. Numerical and simulation results are presented to confirm the performance gain of the considered scheme.