Reshaping Cellular Networks for the Sky: The Major Factors and Feasibility

In this paper, we investigate the feasibility of using the existing cellular infrastructure for drone operations. To this end, we derive an exact expression for the coverage probability of the ground and drone users by considering a practical cell association strategy. Our analytical framework includes base station (BS) height and antenna radiation pattern, drone antenna directivity, and the impact of various propagation environments. We identify several of the system factors that play major and minor roles. Our results show that in contrast to the ground users, the impact of noise and non-line-of-sight (NLoS) components for the evaluation of drone performance are negligible and hence the coverage probability can be significantly simplified. We investigate tradeoffs resulted from altitude-dependent variation in the aggregate interference, the BSs antenna gain, and the number of LoS BSs seen by a drone. Finally, the impact of network densification is studied which shows the coverage performance of a drone converges to zero considerably faster than that of a ground user, however, lowering the drone flying altitude significantly improves its performance in a very dense network.