Outage Performance of Cooperative NOMA-Inspired Overlay CR System with ISIC and ICSI

This study explores a cooperative overlay cognitive radio (CR) system based on non-orthogonal multiple access (N-OMA) within a satellite-terrestrial network context. In this configuration, a secondary user (SU), functioning as a terrestrial ground station, utilizes the licensed spectrum of a primary user (PU) satellite system through N-OMA principles. The paper presents asymptotic expressions for the outage probability (OPr) of both PU and SU under higher signal-to-noise ratio conditions, considering the effects of imperfect successive interference cancellation (ISIC) and imperfect channel state information (ICSI). Additionally, the analysis investigates power allocation strategies aimed at either prioritizing the PU or achieving fairness between the PU and SU. The diversity orders of both users are examined to evaluate overall system performance. Furthermore, the influence of ICSI, detection thresholds, and power distribution on the OPr is assessed. The theoretical findings are supported by extensive Monte Carlo simulations, confirming the validity and precision of the analytical results. This investigation provides insights into optimizing spectrum utilization while maintaining the performance of both PU and SU, making it a valuable contribution to satellite-terrestrial communications using N-OMA in cognitive radio systems.