This paper investigates the performance of nonorthogonal multiple access (NOMA) based hybrid satelliteunmanned aerial vehicle (UAV) systems, where a low Earth orbit
(LEO) satellite communicates with the ground users via a decode
and forward (DF) UAV relay. We investigate a two NOMA users
system, where a far user (FU) and a near user (NU) are served by
the UAV which is located at a certain height above the origin of the
coverage circle. The channel between satellite and UAV is assumed
to follow a Shadowed-Rician fading and the channels between UAV
and users are assumed to follow a Nakagami-m fading. New closedform expressions of the outage probabilities for the two users and
the system are derived. Different from other work in literature, we
take into consideration different parameters affecting the total link
budget. Additionally, we propose an algorithm for minimizing the
system outage probability. The mathematical analysis is verified by
extensive representative Monte-Carlo (MC) simulations. Finally,
simulations are provided to demonstrate the impact of important
parameters on the considered system as well as the superiority of
the NOMA scheme the over reference scheme.