Modelling unmanned aerial vehicles base station in ground-to-air cooperative networks

After disasters, road side units, which can provide wireless communications to vehicles, may fail due to physical damages or power outages. Vehicle-to-vehicle communication also may not perform well owing to lack of neighbours in low vehicle density scenario or collisions in high vehicle density circumstance which may happen in disaster areas. In this study, the deployment of unmanned aerial vehicles (UAVs) as flying base stations to improve connectivity among vehicles in disaster affected areas is analysed. First, the connectivity among vehicles as a function of the altitude of the UAV is derived. Furthermore, multiple UAVs scenario is analysed to determine the minimum number of UAVs needed to guarantee a target connectivity threshold among vehicles for a given geographical area and vehicle density. Numerical and simulation results verify that there exist optimal UAV altitudes for different scenarios as shown in the authors' analyses, and the simulation results also verify that the number of UAVs must be larger than a certain value to guarantee a target connectivity threshold among vehicles.