  Aerial base stations are a promising technology to increase the capabilities
of the existing communication networks. However, the existing analytical
frameworks do not sufficiently characterize the impact of ground interferers on
the aerial base stations. In order to address this issue, we model the effect
of interference coming from the coexisting ground networks on the aerial link,
which could be the uplink of an aerial cell served by a drone base station. By
considering a Poisson field of ground interferers, we characterize the
aggregate interference experienced by the drone. This result includes the
effect of the drone antenna pattern, the height-dependent shadowing, and
various types of environment. We show that the benefits that a drone obtains
from a better line-of-sight (LoS) at high altitudes is counteracted by a high
vulnerability to the interference coming from the ground. However, by deriving
the link coverage probability and transmission rate we show that a drone base
station is still a promising technology if the overall system is properly
dimensioned according to the given density and transmission power of the
interferers. Particularly, our results illustrate how the benefits of such
network is maximized by defining the optimal drone altitude and signal-to-
interference (SIR) requirement.
