Joint Relay/Antenna Selection and Precoding Design for Two-Way MIMO Amplify-and-Forward Relaying Systems

In this paper, a unified framework of relay/antenna subset selection and transceiver design is proposed for a dual-hop two-way amplify-and-forward (AF) multiple-input-multiple-output (MIMO) relaying system in correlated fading channels. By making use of the singular value decomposition (SVD) technique, the joint design of two-source transceivers and multirelay precoders is developed based on the minimum-mean-square-error (MMSE) criterion. This MMSE-based optimization leads to a highly nonlinear objective function of sources and relaying precoders under power constraints so that an iterative search algorithm is applied to explore the optimal power allocation. Simulation results show that the SVD-based joint design of relay and source precoders, in conjunction with the SVD-based relay-and-antenna selection scheme, is capable of achieving superior performance in terms of bit error rate (BER) with an alleviated demand on relays and associated antenna pairs.