Safeguarding Next Generation Multiple Access Using Physical Layer Security Techniques: A Tutorial

Driven by the ever-increasing requirements of ultra-high spectral efficiency,ultra-low latency, and massive connectivity, the forefront of wireless researchcalls for the design of advanced next generation multiple access schemes tofacilitate provisioning of these stringent demands. This inspires the embraceof non-orthogonal multiple access (NOMA) in future wireless communicationnetworks. Nevertheless, the support of massive access via NOMA leads toadditional security threats, due to the open nature of the air interface, thebroadcast characteristic of radio propagation as well as intertwinedrelationship among paired NOMA users. To address this specific challenge, thesuperimposed transmission of NOMA can be explored as new opportunities forsecurity aware design, for example, multiuser interference inherent in NOMA canbe constructively engineered to benefit communication secrecy and privacy. Thepurpose of this tutorial is to provide a comprehensive overview on thestate-of-the-art physical layer security techniques that guarantee wirelesssecurity and privacy for NOMA networks, along with the opportunities, technicalchallenges, and future research trends.