Secure MISO-NOMA Transmission With Artificial Noise

This correspondence studies a new secrecy beamforming (SBF) scheme for multiple-input single-output non-orthogonal multiple access (MISO-NOMA) systems. In particular, the proposed SBF scheme efficiently exploits artificial noise to protect the confidential information of two NOMA assisted legitimate users, such that only the eavesdropper's channel is degraded. Considering a practical assumption of the imperfect worst-case successive interference cancellation which is a unique character in employing NOMA transmission, we derive a closed-form expression for the secrecy outage probability to characterize the secrecy performance. After that, we carry out an analysis of secrecy diversity order to provide further insights about secure MISO-NOMA transmission. Numerical results are provided to demonstrate the accuracy of the developed analytical results and the effectiveness of the proposed SBF scheme.