Terahertz Band UAV Base Stations for Post-Disaster Communication

In case of emergency, data rate demand significantly increases, whereas the current disaster relief bands are not sufficient to supply this demand. Also, existing terrestrial base station infrastructure may be out of use. On the other hand, terahertz (THz) communication attracts attention due to the available massive bandwidth, promising a very high data rate. Moreover, employing an unmanned aerial vehicle (UAV) base station (BS) is a suitable solution for reliable communication links during search and rescue operations. Hence, in this work, we propose and analyze THz band UAV BS for disasters; consequently, a wideband channel in an unstandardized THz band can be utilized for disaster relief, providing sufficient capacity for high data rate demanding applications. In this study, the capacity performance and the outage probability of THz band UAV BS are evaluated for ground-to-UAV communication links compared to existing disaster relief bands considering beam misalignment fading, turbulence fading, and rain and fog effects, yielding encouraging results. In case a disaster affects a huge area, causing terrestrial base stations to be out-of-use, two alternative scenarios are studied. As a first scenario, the UAV-to-satellite communication link is considered for the THz band, sub-6 GHz disaster relief band, and free space optics, resulting in dramatic capacity reduction because of the high loss in the UAV-to-satellite link. As a second scenario, multi-hop UAV communication is considered by deploying multiple UAVs to connect the nearest available terrestrial BS. Simulation results reveal that the THz band UAV BS stands out as a promising candidate for post-disaster communication since it can provide tens of Gbps ergodic capacity for the ground-to-UAV link, and up to 5 Gbps ergodic capacity is obtained in the multi-hop communication scenario in case of outage in large areas.