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Periodic Reporting for period 2 - FACT (FUTURE ALL AVIATION CNS TECHNOLOGY (FACT))

Reporting period: 2021-07-01 to 2022-12-31

The expected increase of air traffic density and diversity (e.g. drones, urban air mobility (UAM)) requires inevitably deployment of new technical approaches to support information sharing and at minimum maintain the level of safety we have today. One of the key enablers of operational safety is a wide deployment of affordable and interoperable communication, navigation and surveillance (CNS) capabilities across all types of airspace users. Performance-based integrated communication, navigation, and surveillance (iCNS) concept aims to allow faster and simpler integration of new CNS technologies to aviation eco-system, as well as more efficient use of existing technologies and resources (e.g. usage of spectrum).

The primary goal of the project FACT was to demonstrate and evaluate the feasibility of such performance-based iCNS concept focusing on a potential use of a public or dedicated cellular networks (4G and 5G) as a complement to the existing CNS technologies in air traffic management (ATM) and U-space environment. Furthermore, by addressing both existing and new airspace users such as drones, the project aimed to build the bridge between future U-space (expecting fully digital and highly automated) and conventional ATM systems considering both technological and users’ perspectives.

Use of cellular networks for aerial operations was explored within the project in terms of two potential solutions:
• Use of public 4G/5G cellular networks for low altitude operations;
• Use of dedicated 5G network.

The project aimed to indicate both opportunities and performance limitations of public cellular networks when used for airborne operations and provide recommendations how the iCNS concept may benefit from them. Such evaluation is essential as cellular technology seems to meet the critical needs of many airspace users operating at low altitudes such as drones, UAM, and GA aircraft: light weight, low electric power consumption (compared to the existing analogue transmitters/receivers), and low prices due to mass production.
While use of public networks can leverage existing infrastructure, it imposes considerable performance limitation (mainly in terms of availability and due to absence of guaranteed service-level agreement), particularly if considered for safety related applications. On the other hand, dedicated 5G networks have potential to support even safety critical CNS applications, however, a significant initial investment is needed for building such infrastructure.
Project’s activities were organized into two iterations of technical design and operational definition process each of which being documented in a package of three deliverables: Concept of Operations, Functional architecture, and System requirements. Each design step was followed by a block of validation activities, the latter one being focused on the project’s operational demo. In addition, business aspects of the explored CNS approach were analyzed in parallel.

Project’s technical evaluations of 4G/5G performance covered primarily the following characteristics measured mostly in public networks:
• End-to-end communication performance for selected ATM applications, namely: Traffic surveillance through regular position reporting over cellular network, FIS/TIS services provided over cellular network, Ground alerting service to relevant vehicles.
• Evaluation of possible improvements of link availability (on airspace users’ side)
• Impact of network load on quality of service
• Positioning capabilities in currently deployed 4G/5G networks

For operational demo, the project implemented CNS enablers (both airborne and on the ground) allowing to demonstrate the following applications for GA, rotorcrafts, and drones:
• Situation awareness applications enabled by cooperative traffic surveillance based on vehicle’s position reporting over cellular network and ADS-B.
• Conformance monitoring & alerting functions which are essential for efficient use of trajectory-based strategic deconfliction.
• Emergency voice link between ATCo (Air Traffic Controllers) and remote pilots.

Project operational demo was successfully performed in July 2022 at Eskisehir using Cessna 172S, Sikorsky S76 B helicopter, and two drones, with active involvement of ATC centre.

Project’s results and conclusions indicate that despite its performance limitations, the use of public 4G/5G network can improve safety in uncontrolled airspace and project provides some practical recommendations how to mitigate potential risks and performance limitations.

Within the project, validation activities applicable to dedicated 5G networks were very limited, however, based on dedicated workshops, analysis of 3GPP standards (Releases 16 and 17), and literature survey, dedicated 5G networks have clearly potential to support even safety critical CNS applications in terms of communication and positioning capabilities. Nevertheless, building such type of infrastructure will require a sufficiently strong business case as well as a clear spectrum strategy. Addressing these two aspects through a coordinated approach across all involved stakeholders will be critical for successful exploitation of this technology for aerial operations.

Project’s activities and results were presented at multiple major conferences/events including SESAR Innovation Days 2021 and 2022, EU Drone Days in 2022, Airspace World 2023, or Joint CNS Stakeholders Platform (JCSP) meeting. In addition, an Advisory Board workshop was organized by the project in 2021. Three scientific papers were prepared at the end of the project.
One of the key motivations for use of the cellular technology in ATM is its potential affordability due to reuse of existing infrastructure driven by other commercial applications and availability of affordable COTS communication chips. These assumptions are valid when considering use of existing public cellular networks. Nevertheless, these networks are not designed for aerial use neither for safety critical applications which leads to serious performance limitations. Project focused on exploring these limitations more in detail, evaluation of their impact on selected ATM functions, and addressing how and to which extent they could be mitigated in real operational environment.

5G technology provides advanced features which can meet in principle requirements of the most stringent ATM/U-space applications; however, these features are not usually deployed in public networks. Their potential deployment requires building of customized/dedicated network, and such investments is strongly dependent on a sufficiently strong business case. While the project addressed some technical elements of 5G technologies, that can support these discussions, building of such business case will need to be addressed in future ideally through a coordinated approach of ATM/U-space stakeholders.