  We consider a relay network based on Unmanned Aerial Vehicles (UAV).
Terrestrial Base Stations (TBS) and UAV Relay Nodes (RN) are modelled using two
Homogeneous Poisson Point Processes (HPPP). UAVs can hover at a fixed position
or move following specific displacement schemes. The Coverage Probability (CP)
of a typical user equipment (UE) is derived, either when it communicates via a
direct link (from the TBS to the UE) or via a relay link (from the TBS to the
UE through a UAV RN). Every link can be in Line-of-Sight (LoS) or Non
Line-of-Sight (NLoS), and suffers from Rician fading with distance-dependent
parameters. This coverage is calculated by means of both stochastic geometry
(SG) and Monte-Carlo (MC) simulations. The benefits of the use of UAV as RNs
are analysed depending on their altitude, density, and mobility scheme.
