# Trajectory optimization and resource allocation for UAV-assisted relaying communications

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## Abstract

In this paper, we study the unmanned aerial vehicles (UAV) assisted relaying communication system, where a UAV acts the mobile relay and provides the information transfer from the source to the destination. The simultaneous wireless information and power transfer techniques are considered at the UAV relays, where the UAV harvests energy from the source node, and exclusively uses the harvested energy for the data relaying. To maximize the system throughput, we jointly consider the UAV trajectory optimization and resource allocation problem, where the UAV trajectory is optimized the UAV positions to harvest the benefits of the line-of-sight links, and resource allocation, including power allocation and the subcarrier allocation, is used to achieve optimal network performance with the power constraints. An alternating maximization algorithm is proposed to solve the optimization problem, in which the UAV trajectory optimization and resource allocation are solved iteratively to maximize the total throughput. Compared with other benchmarks, the proposed algorithm can achieve higher throughput by the benefits from UAV trajectory optimization and resource allocation.

## Keywords

Unmanned aerial vehicles Mobile relays Trajectory optimization Power allocation SWIPT## Notes

### Acknowledgements

The work of B. Liu, Q. Zhu, and H. Zhu was supported in part by the National Natural Science Foundation of China (61871446, 61971239, 61701201, 61427801), and in part by the Postgraduate Research & Practice Innovation Program of Jiangsu Province under Grants (KYCX18_0893). The work of B. Liu was also supported in part by the Natural Science Foundation of Jiangsu Province (No. BK20170758) and in part by the China Scholarship Council.

### Compliance with ethical standards

### Conflict of interest

The authors declare that they have no conflict of interest.

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