Rate Maximization of UAV-Assisted Ambient Backscatter Communications

Unmanned aerial vehicle (UAV) has been extensively deployed to improve wireless coverage due to its high mobility, while ambient backscatter communication has the advantage in improving the energy efficiency. Thus, UAV can be employed to assist ambient backscatter communications when the ground source is unavailable. In this letter, a UAV-assisted ambient backscatter communication scheme is investigated to maximize the average transmission rate of backscatter users by jointly optimizing the user scheduling, transmit power and UAV's trajectory. The formulated problem is non-convex with integer variables, which is solved by a three-stage iterative algorithm. The user scheduling is first approximately solved. To accelerate the convergence, a coarse optimization scheme is then proposed to obtain the preliminary transmit power and trajectory. Finally, a fine optimization scheme is adopted to improve the accuracy. Simulation results show that the backscatter rate can be effectively enhanced by the proposed scheme.