Coverage Extension with UAV Based on Constrained Uplink and Downlink Phases for Disaster-Resilient Communication Networks

Unmanned aerial vehicles (UAVs) have been considered as a solution to extend coverage for disaster-resilient communication networks in a disaster area when the communication infrastructure which is known as the base station (BS) cannot afford the service as usual. However, when the link between the UAV and the serving BS is constrained, the UAV must keep the appropriate distance for reliable transmission. In addition, the altitude of the UAV may significantly affect the link quality between the UAV and the BS, as well as the link between the UAV and the users/rescuers. In this paper, we analyze the coverage of the disaster-resilient communication network with a UAV for guaranteeing the reliability of all links. We show that the position of UAV can be a function of the BS's and user's elevation angle. The simulation results show that the maximum radius of coverage in the high-rise urban environment can be 5.25 km and 2.46 km for downlink and uplink, respectively. Moreover, this paper can provide a principle for the central emergency operation center (CEOC) to immediately deploy the disaster-resilient communication network.