Performance-Controlled Relay Selection for Non-Orthogonal Multiple Access System Under Imperfect Successive Interference Cancellation

In order to improve the performance of non-orthogonal multiple access (NOMA) system, a downlink NOMA system with two symmetric users is investigated. By noting that the requirement of reliability for these two users is different in some practical transmission scenarios, a performance-controlled max-min relay selection scheme for near-user and far-user is proposed. According to the practical transmission requirements, the outage performance of these two users can be controlled by different settings in the considered system. Considering the influence of the imperfect successive interference cancellation (SIC) in the practical scenarios, the exact outage performance of the far and near users in the system is analyzed, and the approximation results in high signal-to-noise ratio are also obtained. Based on the analysis of the approximate results, the optimal power allocation factor for the outage performance of these two users is obtained. Finally, the correctness of the theoretical results is verified by simulation analysis. © 2022, Shanghai Jiao Tong University.