Joint Beamforming and User Selection in Multicast Downlink Channel under Secrecy-Outage Constraint

In this letter, we study the beamforming and user selection problem in multicast MISO wiretap-channel, where a base station (BS) with N_t antennas broadcasts a common confidential message to M legitimate users (Bobs) and N unauthorized users (Eves) attempt to eavesdrop the message. We target at maximizing the minimum secrecy-outage rate of Bobs and propose an iterative successive convex approximation (SCA) algorithm to tackle the original nonconvex problem. We further develop joint semidefinite programming (SDP) and SCA algorithm to find a feasible subset where legitimate users are guaranteed to their requirements. Simulation results are provided to evaluate the proposed approaches.