Joint Relay Processing and Power Control for Two-Way Relay Networks Under Individual SINR Constraints

This paper proposes an iterative algorithm, with which the relay processing matrix and power control can be realized jointly in two-way relay networks consisting of multiple pairs of single-antenna users and one multi-antenna relay station (RS). The users pairs in these networks exchange their information through the half-duplex RS. The joint processing scheme is formulated by including the design of the processing scheme at the RS and the transmit power of each node. Take the consideration of fairness among users, the scheme is written as an optimization problem which is formulated to minimize the total transmit power of all nodes subject to the individual signal to interference plus noise ratio (SINR) of each user. An iterative algorithm is proposed to solve the formulated non-convex joint optimization problem. The relay processing matrix is designed to maximize the SINR of each transmission link by using the uplink-downlink duality theory. In addition, theoretical analysis and simulation results demonstrate that with the given processing matrix at the RS, the total transmit power is a convex function with respect to the amplifying factor at the RS. The proposed algorithm is proved to converge efficiently.