The use of commercial drones has recently seen a tremendous expansion generating a wide
range of applications. Such applications include goods delivery, remote surveillance, border
control, agricultural or industrial monitoring and disaster relief. Even though the
aforementioned applications span over distinct domains, the commonality among them is the
need for autonomous drones or multi-drone systems capable of effective and safe mission
and flight control and coordination. This makes the wireless connectivity a fundamental
component in these applications. Such connectivity must be reliable and secure, and needs
to support high data volume and short latency in some applications. Most commercial drone
systems employ Wi-Fi for sensor data and proprietary radio technologies for command and
control. Given drones three-dimensional mobility, high relative speeds, and changing
altitude, Wi-Fi does not always meet the stringent service requirements of some envisioned
drone applications. Drones can benefit from the existing cellular network infrastructure in
terms of coverage, reliability, and security at data rates that are sufficient for many
applications. The issue is that cellular networks were not primarily developed and deployed
to be used by flying devices. In this sense, this project aims to establish a theoretical
framework to integrate drones as aerial users into 5G cellular networks. The main goal is to
ensure that, when connected to current cellular networks, drones support data transmissions
at very high data rates in the uplink, while the downlink connectivity remains highly reliable
for remote control and steering. This integration of aerial users into cellular networks should
not impair ground users for which these networks were primarily deployed. A particular focus
is on enabling beyond visual line of sight drone operations. Drone manoeuvres are to be
controlled in real-time by means of command data sent via 5G from a processing entity or a
human operator that receives a video stream from the drone itself. Another key objective is
investigating drone-to-drone communication for applications that require multi-drone
systems. This communication can be performed through the cellular network or by bypassing
the ground infrastructure via direct communication technologies such as Wi-Fi. Both
approaches differ in terms of the provided coverage area, adaptability, security, reliability,
and support of real-time functions. We discuss the applicability domains of each approach to
design a hybrid use of both by proposing a mechanism that opportunistically chooses the
suitable wireless technology in concordance with drone mission planning requirements.