Covert Communication for NOMA-Based Integrated Satellite-Terrestrial Networks

This paper conducts the covert performance analysis of NOMA-enabled integrated satellite-terrestrial networks (ISTNs) assisted by a random-power terrestrial jammer. By adopting shadowed Rician fading for satellite-ground links and Nakagami-m fading for jammer-user links, we first analyze the eavesdropper’s binary power detection model and derive the closed-form expression of the average minimum detection error probability (MDEP). Then, we obtain analytical expressions for the outage probability (OP) of two multiplexed NOMA signals under joint covertness and reliability constraints. Furthermore, a genetic algorithm-based nonlinear joint optimization scheme is proposed to maximize the system covert throughput by jointly optimizing satellite transmit power and NOMA power allocation factor. Finally, Monte Carlo simulation results are provided to validate the correctness of theoretical derivations and reveal key system characteristics. The analysis shows that lighter shadowing and a larger maximum jamming power significantly improve the system’s covert performance, while excessive satellite transmit power will degrade the covert capability.