Abstract—This research investigates the performance of a low complexity Cooperative Relay System (CRS) integrated with Non-Orthogonal Multiple Access (NOMA) over κ-μ fading channels. The system model consists of two users receiving information from a source through direct and relayed links. Key performance metrics, including outage probability and achievable rate, are analyzed in depth. To achieve this, we derive the Probability Density Functions (PDFs) and Cumulative Distribution Functions (CDFs) of the received instantaneous Signal-to-Noise Ratios (SNRs) for both direct and relayed transmissions. These distributions then formulate users’ outage probability and average achievable rate expressions. Additionally, we derive outage probability expressions under the assumption of CRSNOMA with imperfect Successive Interference Cancellation (SIC). The study further explores the impact of relay-to-user distance on system performance and the influence of κ-μ fading channel parameters. A major challenge in conventional CRS-NOMA systems is the reliance on complex power allocation techniques, where symbols must be transmitted with carefully controlled power levels. This adds significant computational complexity and increases system design overhead. To address this, we propose an alternative CRS-NOMA scheme that eliminates the need for power allocation by enabling each symbol to be transmitted at maximum power. This simplification reduces processing complexity and enhances system efficiency, making the proposed model more practical for real-world applications. Monte Carlo simulations are conducted to validate the analytical findings.

Keywords—cooperative NOMA, outage probability, achievable rate, imperfect SIC, half-duplex.

Cite: Said Awad and Mohammed Abdel-Hafez, “Low Complexity Cooperative Relay NOMA Systems: Analytical Evaluation in κ-μ Fading with Imperfect SIC," Journal of Communications, vol. 20, no. 4, pp. 384-393, 2025.

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