On the Outage Performance of Overlay Cognitive STBC-NOMA System With Imperfect SIC

This letter investigates an overlay cognitive Alamouti’s space-time block code-aided non-orthogonal multiple access (STBC-NOMA) system. Approximate closed-form expressions for the system throughput (ST) and the outage probability (OP) of both the primary and secondary networks under imperfect successive interference cancellation (SIC) are derived over Rayleigh fading channels. Moreover, asymptotic expressions of the ST and OP at high signal-to-noise ratio (SNR) regime are also evaluated. It is shown that the proposed system outperforms the system presented by Liping et al. (2020), in terms of both the ST and OP. The letter further investigates the impact of power allocation coefficients on the OP.