  We consider an unmanned aerial vehicle enabled (UAV-enabled) fog-radio access
network (F-RAN) in which UAVs are considered as flying remote radio heads (RRH)
equipped with caching and cooperative communications capabilities. We are
mainly focus on probabilistic/randomized content placement strategy, and
accordingly formulate the content placement as an optimization problem. We then
study the efficiency of the proposed content placement by evaluating the
average system capacity and its energy-efficiency. Our results indicate that
cooperative communication plays an essential role in UAVenabled edge
communications as it effectively curbs the impact of dominant Line-of-Sight
(LOS) received interference. It is also seen that cooperative cache-enabled UAV
F-RAN performs better in high-rise environments than dense urban and sub-urban
environments. This is due to a significant reduction of the received LOS
interference because of blockage by the high-rise buildings, and the
performance gain of cooperative communication on the attending signal.
Comparing the performances of the developed content placement strategy and
conventional caching techniques shows that our proposed
probabilistic/randomized caching outperforms the others in most of the
practical cases.
