SINR balancing approach for network beamforming in cognitive two-way relay networks

In this paper, we consider the problem of distributed network beamforming for a bidirectional cognitive relay network which consists of two secondary transceivers and K cognitive relay nodes and a primary network with a transmitter and receiver, over the same spectrum. For effective use of spectrum, we propose a two-step two-way relaying scheme for cognitive networks. Our aim is to design the beamforming coefficients to maximize quality of service (QoS) for the secondary network while satisfying tolerable interference constraint for the primary network. We show that this approach yields a closed-form solution. Our simulation results show that the maximum achievable SINR improved while the tolerable interference on primary receiver increased.