In this paper, we propose an energy-efficient optimal
altitude for an aerial access point (AAP), which acts as a flying
base station to serve a set of ground user equipment (UE).
Since the ratio of total energy consumed by the aerial vehicle
to the communication energy is very large, we include the
aerial vehicle’s energy consumption in the problem formulation.
After considering the energy consumption model of the aerial
vehicle, our objective is translated into a non-convex optimization
problem of maximizing the global energy efficiency (GEE)
of the aerial communication system, subject to altitude and
minimum individual data rate constraints. At first, the nonconvex fractional objective function is solved by using sequential
convex programming (SCP) optimization technique. To compare
the result of SCP with the global optimum of the problem,
we reformulate the initial problem as a monotonic fractional
optimization problem (MFP) and solve it using the polyblock
outer approximation (PA) algorithm. Numerical results show that
the candidate solution obtained from SCP is the same as the
global optimum found using the monotonic fractional programming technique. Furthermore, the impact of the aerial vehicle’s
energy consumption on the optimal altitude determination is also
studied