Joint Opportunistic Scheduling and Power Optimization for Covert Satellite Terrestrial Integrated Networks

In this research, we explore covert communications in a representative satellite terrestrial integrated network (STIN) which is made up of several potential relays and the public users. To ensure the covertness of downlink transmissions, partial users are used as cooperative jammers. It is proved that our proposed opportunistic scheduling scheme can significantly improve covert performance of the STIN. Specifically, the downlink from satellite to users with the highest signal-to-interference-plus-noise ratio is chosen for covert transmission. On this foundation, the analytical expression of detection error probability at a warden is derived. Moreover, we further derive the effective covert rate, which is the important factor to indicate the efficiency of the considered covert network. Then, to further enhance system's covert performance, the transmit power of the satellite and the jammer are optimized, respectively. Finally, some simulations are presented to show the effectiveness of our proposed scheme, and prove that there exists one best power setting for the covert STIN.