Security resource allocation algorithm for RIS assisted NOMA-UAV networks with statistical CSI of eavesdropper

To enhance the security of communication systems, we propose a resource allocation algorithm for unmanned aerial vehicle (UAV)-assisted non-orthogonal multiple access (NOMA) networks utilizing a reconfigurable intelligent surface (RIS), aiming to maximize the minimum secure rate. The algorithm considers constraints on UAV maximum transmit power, RIS phase shifts, successive interference cancellation (SIC) decoding order, and security outage probability. By leveraging statistical channel state information (CSI) from eavesdropping channels, we formulate a joint optimization model for UAV transmit power, RIS phase shifts, and SIC decoding order. We obtain a precise formula for the security outage probability and convert probabilistic constraints into deterministic constraints. Subsequently, we propose an iterative algorithm based on block coordinate descent, transforming the problem into a convex optimization framework using techniques such as variable substitution, penalty functions, and successive convex approximation for an efficient solution. Simulation results demonstrate that the proposed algorithm significantly enhances the minimum secure rate. Specifically, it achieves performance improvements of 10.3 %, 64.9 %, and 99.5 % over the NOMA without RIS scheme, the OMA with RIS scheme, and the OMA without RIS scheme, respectively. This approach represents a significant advancement in ensuring robust and secure communication in UAV-assisted NOMA networks with RIS integration.