Guaranteeing Positive Secrecy Rate for NOMA System against Internal Eavesdropping

Non-orthogonal multiple access systems will face serious physical layer security (PLS) problems in the present of internal eavesdropper. However, in the existing schemes, it’s difficult to always guarantee the positive secrecy rate of the system. To this end, we consider the PLS against internal eavesdropping in two-users scenario and the beamforming design and optimal power allocation problems are given. The developed analytical results demonstrate that the proposed scheme can absolutely achieve positive secrecy rate if provided sufficient power. Simulation results show that the performance of proposed scheme is better than the existing solutions.