Outage performance of users in CR-NOMA network systems

Abstract

Non-Orthogonal Multiple Access (NOMA) and Cognitive Radio (CR) technologies present viable solutions to mitigate spectrum scarcity in wireless communication systems. This paper focuses on evaluating the performance of CR-NOMA networks, particularly for user devices operating under a Simultaneous Wireless Information and Power Transfer (SWIPT) framework. We derive explicit mathematical expressions for key performance metrics, including outage probability (OP) and system throughput, as they relate to various power allocation coefficients. Comprehensive simulations are conducted to validate our theoretical findings, revealing that appropriate power allocation significantly impacts user fairness and overall network throughput. The analysis covers a wide range of realistic channel conditions, including Rayleigh fading, to ensure robustness. Additionally, our study addresses the challenge of limiting interference to the primary network by optimizing the transmission power of secondary users while adhering to interference constraints. The results show that the primary user device (D₁) consistently outperforms the secondary user device (D₂), emphasizing the importance of strategic resource management. These contributions provide deeper insights into the factors affecting outage performance in CR-NOMA systems, offering effective solutions for enhancing the robustness, fairness, and efficiency of next-generation wireless communication networks.