Outdated Relay Selection in Two-Way Relay Network

In this paper, we consider a two-way relay network (TWRN) with multiple amplify-and-forward (AF) relays, out of which the best one is selected to assist the data communication between two sources. The relay selection is based on the outdated channel state information (CSI), and we study its effect on the system performance in the independent but not necessarily identically distributed (i.n.i.d.) Rayleigh fading channels. In particular, we first derive lower and upper bounds for the outage probability and then present the asymptotic analysis for high signal-to-noise ratio (SNR). We further derive lower and upper bounds, as well as the asymptotic results for the symbol error rate (SER). From the asymptotic results, we can find that the system diversity order remains at unity, as long as the CSI is outdated. Numerical results demonstrate the effects of outdated relay selection on the system performance, and simulation results are also provided to corroborate the theoretical analysis.