Driven by the ever-increasing requirements of ultra-high spectral efficiency,
ultra-low latency, and massive connectivity, the forefront of wireless research
calls for the design of advanced next generation multiple access schemes to
facilitate provisioning of these stringent demands. This inspires the embrace
of non-orthogonal multiple access (NOMA) in future wireless communication
networks. Nevertheless, the support of massive access via NOMA leads to
additional security threats, due to the open nature of the air interface, the
broadcast characteristic of radio propagation as well as intertwined
relationship among paired NOMA users. To address this specific challenge, the
superimposed transmission of NOMA can be explored as new opportunities for
security aware design, for example, multiuser interference inherent in NOMA can
be constructively engineered to benefit communication secrecy and privacy. The
purpose of this tutorial is to provide a comprehensive overview on the
state-of-the-art physical layer security techniques that guarantee wireless
security and privacy for NOMA networks, along with the opportunities, technical
challenges, and future research trends.Comment: Invited paper by Proceedings of the IEE