Secrecy outage probability and strictly positive secrecy capacity of UAV assisted cooperative NOMA system with two untrusted destinations

The volume of confidential information transmitted over 5G networks has increased rapidly due to the widespread adoption of large machine-type communication and Internet of Things (IoT) devices. Secrecy outage probability (SOP) and strictly positive secrecy capacity (SPSC) parameters are crucial parameters used in evaluating the security of wireless systems, particularly in situations where maintaining secrecy is essential. Also, Non-orthogonal multiple access (NOMA) has the potential to improve the performance of wireless communication systems due to its higher spectral efficiency, improved fairness in resource allocation, and enhanced coverage and connectivity. In this paper, we investigate the secrecy performance of unmanned aerial vehicles (UAV) assisted cooperative NOMA system with a half duplex protocol based amplify and forward relay over the Rayleigh fading channel in presence of two eavesdroppers for downlink communication. We derive SOP and SPSC of the proposed system model and analyze its performance in terms of the illegal SNR of eavesdroppers, power allocation coefficient, information rates and Rayleigh channel parameters. Simulation results demonstrate that SOP decreases with a higher value of power allocation coefficient and lower values of the illegal SNR of eavesdropper and lower information rates. SPSC increases with high values of power allocation coefficient of far destination and decreases with lower values of illegal SNR of eavesdroppers and Rayleigh channel parameters. Analytical simulations are verified using Monte Carlo simulations.