Jammer-Aided Secure Communications for Cooperative NOMA Systems

This letter investigates a jammer-aided cooperative non-orthogonal multiple access (NOMA) system, where one relay is used to deliver information and other relays are acted as jammers. Two simple relay selection (RS) strategies, e.g., random RS and max-min RS, are considered in this letter. Analytical and asymptotical expressions for secrecy outage probability (SOP) under both RS schemes are developed. Simulation results show that NOMA system with jammer achieves a lower SOP than the one without jammer in the moderate to high SNR range. Moreover, by adopting max-min RS strategy, the secrecy outage performance can be further improved in the low SNR region, while still tends to a constant in high SNR region.