On the Performance of the Buffer-Aided Relaying Secure Network with the Hybrid NOMA Transmission Strategy

This paper investigates the Long-Term Average Secrecy Rate Maximization Problem (LASRMP) for the bufferaided relaying secure network where transmitters communicate with their corresponding receivers threatened by an eavesdropper. To tackle the non-convex nature of this problem, it is reformulated as a drift-plus-utility minimization problem. This reformulation strikes a balance between maximizing secrecy rates and maintaining queue stability, leveraging the Lyapunov optimization framework. Subsequently, an optimal transmission strategy is designed to select an optimal mode from the nonorthogonal multiple access (NOMA) and orthogonal multiple access, and select an optimal transmission link from the first-hop and second-hop depending on the channel state information and buffer state information. Additionally, optimal power allocation is performed for each mode. Simulation results underscore the superiority of the proposed algorithm over comparative schemes in terms of the secrecy rate.