Joint optimization in multi-relay multi-user bidirectional systems: non-robust and robust cases

This paper considers the precoder design issue of bidirectional networks in which each node is equipped with multi-antenna. In contrast to the conventional research of two way relay network, this paper adopts a more general scenario, a multi-relay multi-user network is considered. Firstly, assuming perfect channel state information is available, this paper investigates the precoding design for the relays and users with aim of minimizing the sum minimum square error. Then, this paper takes a more practical hypothesis into account by analyzing the channel estimation error. Utilizing the alternative optimization method, the main problem is divided into three decoupled subproblems and solved respectively. It is shown that in both cases, the proposed precoding algorithms outperform the existing schemes.