Secure Cooperative NOMA Networks with Full-Duplex Relaying/Jamming: A Physical Layer Security Perspective

Non-orthogonal multiple access (NOMA) is envisioned as a promising technology for achieving both high spectral efficiency and massive connectivity in emerging wireless networks. While the massive connectivity powered by NOMA grants mobile devices more opportunities for access, it also renders the network vulnerable to be intercepted. In this article, the application of full-duplex relaying/jamming technology to NOMA-based cooperative networks against eavesdropping is investigated. Adopting the full-duplex technique, the intermediate node plays two roles in the secure network: 1) coordinates the NOMA transmission and enhances link reliability for legitimate users; 2) emits artificial noise in addition to multi-user interference to deteriorate the received signal quality of any potential eavesdropper. From the perspective of signal processing, we concentrate on the NOMA signal designs, decoding strategies, interference management, and power allocation to improve the secrecy performance under different eavesdropping manners. Moreover, we also discuss some future research directions on this topic.