  This letter investigates the transmit power and trajectory optimization
problem for unmanned aerial vehicle (UAV)-aided networks. Different from
majority of the existing studies with fixed communication infrastructure, a
dynamic scenario is considered where a flying UAV provides wireless services
for multiple ground nodes simultaneously. To fully exploit the controllable
channel variations provided by the UAV's mobility, the UAV's transmit power and
trajectory are jointly optimized to maximize the minimum average throughput
within a given time length. For the formulated non-convex optimization with
power budget and trajectory constraints, this letter presents an efficient
joint transmit power and trajectory optimization algorithm. Simulation results
validate the effectiveness of the proposed algorithm and reveal that the
optimized transmit power shows a water-filling characteristic in spatial
domain.
