Enhanced secure multicast: Joint power allocation and beamforming design based on user clustering

As communication security has become a critical problem in current wireless networks, physical layer security has attracted more and more research interest However, due to the large number of receiving users, traditional physical layer security techniques, e.g., artificial-noise-aided transmit beamforming, do not apply well to multicast transmission. To cope with this problem, an enhanced secure multicast scheme is proposed in this paper, in which multicast users with close channel vectors are divided into a cluster and different clusters are served on different channels. Based on this scheme, a heuristic user clustering algorithm and a joint power allocation and beamforming design algorithm are presented to maximize the globally achievable secure multicast rate. Simulation results show that the enhanced scheme can support a much higher secure transmission rate than traditional secure multicast schemes, and the proposed joint power allocation and beamforming design algorithm outperforms existing exhaustive searching methods greatly in terms of computation complexity.