Secrecy Analysis for NOMA-Based Multi-Antenna Satellite-UAV-Terrestrial SWIPT Systems

In this study, secrecy performance for unmanned aerial vehicle (UAV) relaying multi-antenna satellite-terrestrial simultaneous wireless information and power transfer systems with non-orthogonal multiple access (NOMA) is investigated. Specifically, a multi-antenna satellite communicates with two multi-antenna terrestrial NOMA users via a UAV relay under the wiretapping of a multi-antenna eavesdropper, which is randomly distributed. In addition, a maximum ratio transmission scheme is adopted at the satellite to transmit the information, and both a maximum ratio combining and a power splitting schemes are taken into account to process the multiple copies of the received signals. Considering the satellite channel is subject to the Shadowed-Rician distribution and the terrestrial channels are with Nakagami-m distributed, the analytical expressions of secrecy outage probability as well as the probability of strictly positive secrecy capacity for both NOMA users with perfect and imperfect successive interference cancellation are obtained by using the stochastic geometry method, and verified with Monte-Carlo simulations.