Capacity analysis of aerial small cells

Providing high-speed communication for mobile users in remote geographic areas or after a disaster occurs is not only critical but also challenging. To counter such challenge, unmanned aerial vehicles (UAVs) have been exploited to provide a fast-deployable and high-speed communication system, where each UAV can serve as an aerial small cell base station to provide WiFi and/or cellular services for the ground users. Despite its fast-deployable and highly maneuverable features, the capacity analysis of aerial small cells is largely missing. To close such gap, a stochastic propagation model for A-to-G aerial channels is first introduced, which takes into account the impact from wave propagation, gaseous absorption, Doppler spread, attitude-dependent shadowing, and multipath fading. Then, by exploiting such model, the area spectral efficiency of the aerial small cells is investigated for both SISO and MIMO cases. Our study reveals the inherent relationship among the area capacity, height and coverage and shows that there exists an optimal attitude that can maximize network capacity and cell coverage.