Secure beamforming method for artificial-noise-aided multiuser broadcast system with users of different importance under secrecy outage probability constraint

In this study, the authors proposed the optimal beamforming (BF) design for multiuser broadcast secure transmission under secrecy outage probability constraint with artificial noise technique. Different from former research papers, their model assumes that different users have different priority and importance. Some users are regarded as main users with a stricter constraint, which make the normal BF algorithm not to gain the best performance. For this reason, they proposed a new BF design method for this specific system model. To deal with intractable non-convex problems, they employed a series of optimisation algorithm like Bernstein-type inequality and second-order cone constraints method to transform these problems into solvable functions. After that, they show the feasibility of their new BF algorithm by Monte-Carlo simulation method, and analyse the influence on transmission and security performance caused by different system parameters. Furthermore, they compare the security performance of their method with the normal BF method, which demonstrates the advantage of the new BF method.