Efficient convex optimization for beamforming in cognitive radio multicast transmission

In this paper, a novel algorithm for transmit beamforming to single cochannel multicast group is presented. The problem of minimizing the total power transmitted by the antenna array subject to interference constraints at the primary receivers and quality-of-service (QoS) constraints at the secondary receivers is addressed. It is shown that this problem, which is nonconvex NP-hard, can be approximated by a convex second-order cone programming (SOCP) problem. Then, an iterative algorithm in which the SOCP approximation is successively refined is proposed. Simulation results show the superior performance of the proposed approach in terms of the total beamforming power, feasibility and computational complexity as compared to the existing ones¹.