Optimum UAV flying path for Device-to-Device communications in disaster area

In this paper, we propose the usage of Unmanned Aerial Vehicle (UAV) as a flying mobile base tower station for discovering Device-to-Device (D2D) devices in the disaster area. In a disaster area, energy consumption of both devices and network become an important constraint. Therefore, there is a need to establish wireless network communication in large area rapidly under the condition of infrastructure failure. The previous works does not calculate the energy consumption of the UAV and consider the use cases of UAV flight path for specific disaster condition, e.g. flood, earthquake, etc. The objective of this paper is to provide UAV flying paths that can adapt according to disaster condition which satisfy the UAV energy constraint. We enhance four schemes for the UAV flying paths: O-path, Rectangular path, ZigZag-path, and S-path. This enhancement reduces the flight path gap area and lead the increasing of covered area. To examine the best UAV flight path for certain disaster cases, several simulations were performed and discussed. The results show that for distributed damage pattern, the optimum UAV flying pattern is an S - path because of its large coverage area (covering around 80 percent of total devices in altitude 100 m). Otherwise, for centralized damage pattern, the optimum UAV flying patterns are O, Rectangular, and Zigzag path because of its short flight duration and less energy consumption (eight times smaller than the S - path in altitude 100 m).