Max-min security energy efficiency optimization for UAV-RIS-enhanced short-packet communication systems^☆

This work focuses on maximizing the minimum user’s security energy efficiency (SEE) in an unmanned aerial vehicle-mounted reconfigurable intelligent surface (UAV-RIS) enhanced short-packet communication (SPC) system. The base station (BS) provides short packet services to ground users using the non-orthogonal multiple access (NOMA) protocol through UAV-RIS, while preventing eavesdropper attacks. To optimize SEE, a joint optimization is performed concerning power allocation, UAV position, decoding order, and RIS phase shifts. An iterative algorithm based on block coordinate descent is proposed for mixed-integer non-convex SEE optimization problem. The original problem is decomposed into three sub-problems, solved alternately using successive convex approximation (SCA), quadratic transformation, penalty function, and semi-definite programming (SDP). Simulation results demonstrate the performance of the UAV-RIS-enhanced short-packet system under different parameters and verify the algorithm’s convergence. Compared to benchmark schemes such as orthogonal multiple access, long packet communication, and sum SEE, the proposed UAV-RIS-enhanced short-packet scheme achieves the higher minimum user’s SEE.