Robust Secure Design for RIS-Aided NOMA Network Against Internal Near-End Eavesdropping

The reconfigurable intelligent surface (RIS) aided non-orthogonal multiple access (NOMA) network is applied to improve spectral efficiency and energy efficiency of wireless systems. Due to the incorporation of NOMA, RIS-aided NOMA system suffers from physical layer security (PLS) problem when an internal near user (NU) is the eavesdropper. In this case, it is difficult to always guarantee positive secrecy rate. Therefore, a scheme of artificial noise (AN) cooperative jamming and beamforming design is proposed against internal eavesdropper for RIS-aided NOMA in this paper. It is proved theoretically that the positive secrecy rate can be guaranteed if providing sufficient power. In addition, the power allocation of base station is further studied to minimize the total power consumption under the constraints of data rate and secrecy rate, and the closed-form solutions are achieved. Simulation results show that the performance of the proposed scheme is superior to the existing solutions.