Secrecy Outage-Constrained Robust Resource Allocation Design for MU-MISO RSMA Systems

In this paper, we study the robust and fair transmission design for a rate splitting multiple access (RSMA)-based multi-user multiple-input single-output (MU-MISO) probabilistic secrecy communication system, where the statistic distribution of estimation errors of eavesdropping channels is available at the transmitter. Our robust resource allocation design aims to maximize the minimum achievable outage constrained (OC) secrecy rate among multiple single-antenna legitimated users (LUs) via optimizing the beamforming vectors and the artificial noise (AN) matrix at the transmitter. To this end, the algorithm design is formulated as a non-convex probabilistic optimization problem which takes into account the maximum transmit power budget. To address the intractability of the optimization problem, the successive convex approximation (SCA) technique and the alternating optimization (AO) approach are exploited to design a suboptimal iterative algorithm for obtaining a locally optimal solution of the considered problem. Simulation results demonstrate that the minimum achievable OC secrecy rate performance of our proposed RSMA-based probabilistic secure transmission system outperforms that of several baseline schemes.