Reliable communications are central to safe drone operations
Drones rely on a high level of digitalisation to operate autonomously and depend upon datalink communications to achieve this. Command and control (C2) information needs to be reliably transferred in support of functions and specific procedures, enabling drones and manned vehicles to operate safely in the same airspace. The DroC2om project reviewed the capability of the existing cellular and satellite infrastructure that supports C2 datalink communications, using live flight trials and simulations to test availability and performance. The research led to the definition of an integrated communications concept incorporating cellular and satellite datalinks, which is contributing to EUROCAE and 4G/5G standardisation work.
Project partners assessed the reliability of the combined cellular – satellite radio network architecture and radio mechanisms. One of noted challenges is the operating conditions for drone radio channels, which are reasonably known for the satellite communication channel commonly used by large drones, however limited investigation has been carried out on the cellular channel and the operating conditions which prevail at drone heights up to 150 metres. The Droc2om project included experimental investigations to bring further clarification on this in order to design radio technology that makes the C2 link operate with specified reliability with specific reference to service level compliance and latency. Based on DroC2om initial investigations, the project partners found that interference management presents a challenge to the reliable operation of the C2 datalink and proposed solutions for further simulation and research.
Proposals to address connectivity issues include: Increasing the number of antennas on the drone, with a simple selection mechanism; and adding different networks connections and operators. The solutions are moderately complex and designed for when density of drones increases.
The project provided solid empirical evidence on the drone to cellular networks channel in urban areas and validated dual LTE C2 performance using live trials. It also tested multi-link connectivity and beam switching to ensure drone C2 link quality is maintained in highly loaded cellular networks. It concluded a hybrid cellular- satellite architecture, combining low latency and coverage of cellular with reliability of satellite communications, contributes to robust C2 performance.
