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In this letter, we investigate a robust transmit optimization design based on an artificial noise (AN)-aided precoding scheme for maximizing secrecy rate in a multiple-input multiple-output multiple-eavesdropper multicast network where a transmitter sends confidential information to multiple intended users and provides energy for multiple idle nodes while multiple passive eavesdroppers try to overhear the secret information. Supposing Gaussian CSI uncertainties, the proposed outage-constrained secrecy rate maximization (OC-SRM) problem is nonconvex and its analytical analysis is more challenging than several existing OC-SRM schemes. Technically, to circumvent this mathematically intractable secrecy problem, we resort to low SNR approximation and some conservative approximations (e.g., Bernstein-type inequality and sphere bounding) to reformulate the OC-SRM problem into two convex subproblems which can be efficiently solved by the off-the-shelf optimization solver. Simulation results are provided to validate the security performance of the robust AN-aided precoding design.

We investigate physical layer security in wireless communication networks, where a transmitter Alice sends a confidential message to an intended user Bob, while coexisting with a normal transmitter DT, a normal receiver DR, and a passive eavesdropper Eve. Compared with the conventional cooperative jamming (CJ) scheme, DT has dual responsibilities. One is to broadcast public information to its service subscriber DR, and the other is to confound the unauthorized eavesdropper Eve to ensure desired secure communication. Considering the secrecy outage restriction of Bob and the quality of service demand of DR, we propose an optimal resource management strategy. Users with different security requirements take hierarchical secure measures. For example, banking transaction needs to adopt high strength security measures, and personal voice communication resorts to low-level security protection strategies. Numerical simulations show that the proposed secure design outperforms the CJ scheme in terms of effective service rate and effective energy efficiency with a little secrecy rate loss, which is suitable for the low-level security real-time communication.