  This paper studies the improvement of the achievable end-to-end data rate of
ground users assisted with unmanned aerial vehicles (UAVs) and tethered
balloons (TBs). The goal is to maximize the end-to-end throughput of a network
suffering from the absence of terrestrial infrastructure. First, we solve an
integer linear programming problem to optimize the associations. Then, we solve
the UAVs transmit powers optimally by converting the problem into a convex one.
Subsequently, an efficient algorithm is proposed to optimize the UAVs
placement. Finally, our mathematical formalism is illustrated with some
selected numerical results that show the advantages provided by our proposed
scheme.
