Effect of channel estimation error on multiuser two-way relaying with asymmetric data rates

In this paper, we propose antenna selection (AS) and user scheduling schemes in multiuser two-way relaying (TWR) networks, where a multi-antenna base station (BS) and several single-antenna users (USs) exchange information via a single-antenna relay terminal under the influence of asymmetric rate requirements and channel estimation error (CEE). The considered AS and user selection schemes maximize the overall end-to-end signal-to-noise ratio (SNR) in the presence of CEE and different data rates. For bidirectional information exchange, AS is adopted at the BS with user selection. In particular, we deduce new expression of overall outage probability (OOP) for the considered system under independent and identically distributed (i.i.d.) Rayleigh fading channels. We further derive new compact asymptotic outage expression in the high SNR regime to reveal the impact of CEE and different target rates onto the system diversity order. Based on the asymptotic expression, we formulate a concise solution for the relay location to maximize the system performance. Lastly, our analytical findings are verified through numerical and simulation results.