A distributed user scheduling scheme for MIMO multi-way relay channel

A simple distributed user scheduling (DUS) scheme is proposed for the MIMO multi-way relay channel (MWRC), where K (K ≥ 2) M-antenna (M ≥ 2) users are selected from K clusters of users to conduct all-cast information exchange via an M-antenna amplify-and-forward (AF) relay. In particular, the proposed DUS is based on the individual performance metric calculated by each user with its local channel state information (CSI). Therefore, DUS bypasses global CSI and complicated computations at the scheduling center, both are often inevitable with traditional centralized user scheduling (CUS). Furthermore, the outage performance of DUS is analyzed and the achievable multi-user diversity (MuD) order is derived. Numerical results validate the theoretical derivations and show that DUS achieves comparable performances to CUS in the considered scenarios.