Performance analysis of secure NOMA wireless system over Rician fading channels

With the current deployment of 5 G communication and its promise to respond to the ever-increasing demand for high data rates, extensive research has focused on advanced multiple access techniques. Non-Orthogonal Multiple Access (NOMA) is a potential candidate for enhancing spectral efficiency and supporting massive connectivity among the most promising multiple access techniques. However, the multiplexing nature of the NOMA makes it vulnerable to security threats, not only from external jammers and eavesdroppers but also from internal malicious users, who can utilize successive decoding to get access to unauthorized confidential data from other users sharing the same resources with them. Consequently, ensuring the security and integrity of NOMA internal structure is crucial. The proposed work in this paper analyzes the security and reliability of NOMA users in a downlink system operating over a Rician fading channel. We derive closed-form expressions for outage probability (OP) and secrecy outage probability (SOP). Based on the OP and SOP expressions, we formulate an optimization problem to minimize the system outage probability without compromising security, and we employ Particle Swarm Optimization to optimize resource allocation in NOMA systems to reach this goal. Extensive simulations validate our results and provide valuable insights into.