An SINR Balancing Technique for a Cognitive Two-Way Relay Network

We propose a two-way relay based spatial multiplexing technique for a cognitive radio relay network (CR). The relay coefficients and the transmission powers are optimized to maximize the worst-case user signal-to interference and noise ratio (SINR), while ensuring interference leakage from the relays to the primary users (PUs) in the network is below a threshold. We solve this problem through an iterative procedure that uses semidefinite and geometric programming along with bisection search method. We evaluate the performance of the proposed scheme in terms of the mean SINR for different number of relays and transmission power at the relays.