Performance of preprocessing-aided relay-assisted uplink communication

In this paper, we study the performance of cooperative diversity aided uplink (UL) communications with fixed infrastructure based decode and forward (DF) relays each equipped with multiple antennas. Source mobile stations (MSs) exploit these infrastructure based relays to communicate with the base station (BS). The links D and T connecting the source MS to the BS and the source MS to the relays, respectively are assumed to be frequency non-selective and the link R from the relays to the BS is assumed to experience Nakagami-m fading. Specifically, in this paper, we investigate the performance of cooperative diversity in the context of UL communications with singular value decomposition (SVD) based transmitter preprocessing (TP) at the relays to mitigate multi-user interference (MUI) at the BS for two cases, (i) the relays are far away from each other so that MUI at the relays is negligible and (ii) the relays are closer to each other so that MUI is dominant. Our simulation studies show that this TP aided relay diversity system performs well in multi-user interference limited environment by completely eliminating the uplink MUI. Moreover, this approach results in better achievable bit error rate (BER) than conventional cooperative diversity system employing multiuser detection (MUD).