How to ensure reliable connectivity for aerial vehicles over cellular networks

Widely deployed cellular networks are an attractive solution to provide large scale radio connectivity to unmanned aerial vehicles. One main prerequisite is that coexistence and optimal performance for both aerial and terrestrial users can be provided. Todays cellular networks are, however, not designed for aerial coverage, and deployments are primarily optimized to provide good service for terrestrial users. These considerations in combination with the strict regulatory requirements, lead to extensive research and standardization efforts to ensure the current cellular networks can enable reliable operation of aerial vehicles in various deployment scenarios. In this paper we investigate the performance of aerial radio connectivity in a typical rural area network deployment using extensive channel measurements and system simulations. First, we highlight that downlink and uplink radio interference play a key role and yield relatively poor performance for the aerial traffic when load is high in the network. Secondly, we analyze two potential terminal side interference mitigation solutions: interference cancellation and antenna beam selection. We show that each of these can improve the overall, aerial and terrestrial, system performance to a certain degree, with up to 30 percent throughput gain and an increase in the reliability of the aerial radio connectivity to over 99 percent. Further, we introduce and evaluate a novel downlink inter-cell interference coordination mechanism applied to the aerial command and control traffic. Our proposed coordination mechanism is shown to provide the required aerial downlink performance at the cost of 10 percent capacity degradation in the serving and interfering cells.