Iterative MMSE filter design for multi-pair two-way multi-relay networks

In this paper, a bi-directional communication between K node pairs is considered. Each of the 2K nodes has multiple antennas. There is no direct link between the nodes. Q half-duplex relays each with R antennas support the communication. Two-way relaying is assumed. The linear transmit filters, relay filters and receive filters are designed iteratively to minimize the mean square error (MMSE) subject to power constraints at the nodes and at the relays. It is guaranteed that the proposed scheme achieves a local minimum of the objective function. The proposed iterative MMSE algorithm can also be applied to a unidirectional communication based on one-way relaying. Simulation results show that at low and moderate signal to noise ratios, the proposed iterative MMSE scheme performs better than other MMSE based and interference alignment based two-way and oneway relaying schemes known in the literature.