Joint Trajectory and Resource Optimization for AAV-Relayed Multiuser SWIPT

Unmanned aerial vehicle (UAV) assisted relaying has become the focus of the next generation network owing to its superiority of low cost and swift deployment. In addition, the orthogonal frequency division multiplexing (OFDM) based simultaneous wireless information and power transfer (SWIPT) is known to have significant advantages in system complexity compared to the traditional time-switching (TS) and power-splitting (PS) techniques. Since the UAV is known to have limited size, weight and power, we investigate the OFDM-based SWIPT for a multi-source-destination UAV relaying system in this paper. With the purpose of maximizing the average transmission rate (ATR) under the constraint of the harvested energy, we jointly optimize user scheduling, resource allocation and UAV trajectory. To tackle this issue, we first divide it into three subproblems of user scheduling, power and subcarrier allocation, and UAV trajectory optimization. Subsequently, the user scheduling subproblem is optimally solved. The power and subcarrier subproblem is approximately solved by addressing its dual problem and the UAV trajectory optimization subproblem is addressed by successive convex approximation technique. Then, we put forward an iterative algorithm based on block coordinate descent method by solving the three subproblems alternately. Numerical results demonstrate that our proposed algorithm is preferable than the two benchmark schemes.