CNS as a service – Research shall address potential solutions for the provision of communication, navigation, and surveillance functionalities as a cloud-based or subscription-based service (CNSaaS) by an independent organisation. CNSaaS aims at offering these critical functionalities to aviation stakeholders, such as airlines, aircraft operators, and air navigation service providers, as a service model. Research results shall enable the decoupling of CNS service provision from the physical location of the infrastructure as outlined in the target architecture defined in the European ATM Master Plan.

The scope covers the identification of possible CNS technologies and functions that could be provided as a CNS as a service and the development of relevant business models that could provide these CNS services including the assessment of technical requirements, such as spectrum management and efficiency, redundancy, flexibility of equipage of avionics and cyber security. Note that there is on-going work under project CNS-DSP. Research shall also consider the guidance material on CNS service assessment produced by PJ.14-W2-76 in SESAR 2020. This includes the development of CNS infrastructure monitoring services.

New air/ground technologies for the integration of high-altitude pseudo satellites (HAPS), hypersonic and supersonic vehicles and space launches – Higher airspace operations (HAO) represent one of the most profound changes to the aviation ecosystem for many years. The number of space operations, high-altitude pseudo-satellites (HAPS), supersonic and hypersonic vehicles is set to steadily increase in the years ahead. This research area aims at developing new (or adapting exiting) air / ground CNS capabilities to ensure the safe and efficient integration of hypersonic and supersonic vehicles into ATM. This may include:

• The review / update of navigation services to meet the demands of HAPS, supersonic and hypersonic aircraft, and space launches (e.g., assessing the performance of GNSS systems supplemented with inertial systems to serve as backup during temporary GNSS outages caused by high-speed plasma formation or space radiation effects).
• The integration of space-based ADS-B for tracking HAPS or supersonic and hypersonic aircraft at higher altitudes and speeds and its application for space surveillance and tracking (SST) for HAO. Space-based surveillance enables increased safety, through permanent real-time monitoring of air traffic worldwide, more ecofriendly ATM operations, and stronger resilience to GNSS degradations. It can also contribute to global rationalisation of terrestrial and space surveillance infrastructures through the integration of new space technologies (e.g., small and nano satellites, LEO, etc.).
• The development of non-cooperative surveillance technologies for HAO, based e.g. on technologies in use for space situational awareness (SSA) and space surveillance and tracking (SST), or technologies in use for military surveillance of the airspace.
• Provision of space weather services including emerging requirements for atmospheric observations and forecasts for supporting HAO.
  These technologies are civil/military dual use.

Satellite based multilateration (MLAT) – Nowadays, surveillance tracking systems rely on self-reported positions of aircraft, which are derived from GNSS satellites, which can be affected by interferences caused by different causes (e.g., spoofing, jamming, etc.).

This research element covers the development of a complementary, resilient, space-based surveillance infrastructure, which uses a low earth orbit (LEO) satellite constellation to track aircraft by determining their exact position based on multilateration (MLAT) (i.e., using different times of arrivals of radio frequency (RF) signals). By independently verifying the location of an aircraft through geolocation satellite based MLAT technology, the proposed solution shall be able to track a plane in real time from take-off to landing.

Research shall address the end-to-end validation of the proposed solution including both satellite (space segment and space network) and ground ATM components and determine and validate both functional and non-functional (i.e., performance) requirements. It is acknowledged that performing an end-to-end TRL6 validation with LEO constellation may be challenging; therefore, the proposals shall consider, as a preliminary step, the maturity of the different segments (space segment, space network, ground segment) separately, and clearly identify the risks to achieve TRL6. Also, research shall cover the description of future operations and service definition.

Use of ADS-B phase overlay – The objective is to develop applications that take advantage of the ADS-B phase overlay, for example:

• Secure ADS-B: Currently, there are no means to know if a single ADS-B message is valid or not, or if the sender is real or fake. For verification, surveillance systems correlate several messages and sources, what requires efforts and infrastructure. Research shall aim at completing the R&I work on this use case, to increase the security of ADS-B introducing authentication through the data capacity provided by phase overlay. The research should investigate how secure ADS-B might allow the rationalization of the surveillance infrastructure, especially Mode S. Note that there is on-going work on this use case (to “anonymize” the ADS-B messages) under project MITRANO.
• Applications of ADS-B phase overlay that allow a reduction in the congestion of the 1030/1090 MHz frequency, which can lead to situations where the system performance does not comply with the safety required for specific separation applications, what leads to restrictions to access the airspace, potentially inducing delays and flight cancellation.
  Note ADS-B phase overlay should be developed as a civil/military dual-use technology.

Collaborative cyber security framework for CNS – Current aeronautical cyber security standards, recommended methodologies, and state of the art, responses to cybersecurity-threats and processes are based on some key assumptions:

• Aircraft is managing its own security and certification is managed at aircraft level only.
• Security solutions often rely on a binary trusted/untrusted security model.
• Security working groups and technical standards covering different aspects of the whole architecture work as silos.

Those assumptions may not be sufficient to provide effective and long-term defence against cyber security attacks to automated aeronautical CNS environment.

Research shall aim at defining and validating a global security collaboration framework based on uses cases across CNS domains, considering the end-to-end chain to address cybersecurity at global level. Research shall consider the network level cybersecurity when network is not aviation specific: what kind of cybersecurity requirements need to be put in the service provider, including addressing common points of failure.

Research shall address potential solutions to mitigate radio frequency interference based on different techniques (e.g., filtering out jamming signals, etc.) or evaluating solutions employed in non-aviation applications, dynamic jamming/spoofing information sharing and the potential application of AI in this field. Research shall focus on developing aircraft-installed active radio antennas capable of adapting itself to the attack and mitigating the impact of radio jamming attacks. Military requirements shall be addressed. This research element also covers the monitoring and mitigation of the potential cybersecurity risks that may be introduced with the new entrants (e.g., HAO).

Combined airborne and ground dual-frequency multi-constellation (DFMC) ground-based augmentation system (GBAS) GAST-E approach service – Develop DFMC GBAS (GBAS GAST-E) to maximise the benefits of this technology, including for CAT II/III operations, to allow for more robust operations, including at high and low latitudes with tougher ionospheric conditions. This element also addresses increased resilience to radio frequency interference on a single band and increased resilience to single-constellation outages or failures. This includes the following elements:

• Develop both the DFMC GBAS ground station and the DFMC GBAS airborne receiver to TRL6 for GAST-E and carry out ground–airborne interoperability testing and performance validation. Note that the DFMC GBAS airborne receiver is not yet at maturity level TRL4, and therefore an essential priority would be developing and maturing it as quickly as possible to catch up with the development of the DFMC GBAS ground station, which completed TRL4 in SESAR 2020 under SESAR solution PJ.14-W2-79b “DFMC GBAS – GAST F”[1]. The proposal should address both ground and airborne aspects and include Galileo and EGNOS V3.
• Ensure that the DFMC GBAS baseline development standards and recommended practices (BDS SARPs) adequately covers definition of the interface for downwards compatibility (GAST-D, GAST-C).
• Develop a prediction service to anticipate CAT II/III unavailability due to atmospheric/solar events (forecasting ionospheric conditions and gradients) and to provide an estimate of expected performance in terms of minutes of expected unavailability of the service per year, including potential correlation with low-visibility procedures (if there is any). An alert service that forewarns airspace users in a timely manner of expected outages, prior to the outage happening, is necessary for the safe and efficient conduct of flights.
• Potential use of precise military GNSS signals (e.g., GPS pulse per second (PPS), GALILEO public regulated service (PRS), deemed equivalent to civil signals (e.g., GPS standard positioning service (SPS)), to support military compliance to civil NAV requirements and/or other uses.
• Support standardisation and accelerated certification activities, including:
  • The creation of a new ICAO standard for GAST-E in line with the DFMC GBAS concept and the extension of current GAST-D standards to augment Galileo / EGNOS V3 signals.
  • The provision of standards that would allow the industrialisation of GBAS equipment (ground station and airborne receiver) to ensure the timely delivery and full compatibility of both subsystems.
  • Produce minimum operational performance standards for ground and airborne equipment, based on the work of EUROCAE Working Group 28 (in coordination with the Radio Technical Commission for Aeronautics (RTCA) Special Committee 159).
  • Develop implementation guidelines, considering different airport layouts / levels of complexity.

Ground-based Alternative – Position, Navigation and Timing (A-PNT) – Global navigation satellite systems (GNSS) including Galileo and the European geostationary navigation overlay service (EGNOS), are usually considered as suitable technologies for providing position, navigation, and timing (PNT) information as required. However, GNSS can be subject to local (e.g., interference, spoofing, jamming) or global (ionospheric issues, system fault) outages, and it also presents service limitations in those areas where there is limited sky visibility.

With the objective of having a back-up solution for GNSS as the source of PNT in the situations above, several potential technological solutions have been or are being developed to provide alternate position navigation and timing (A-PNT). The proposed solution aims therefore at enhancing service resilience (e.g., to RFI), availability, and continuity. This requires the support of industry standards to ensure the required interoperability. The proposed solutions should investigate how their developments fit into the larger cross-domain European complementary PNT (C-PNT) framework. The notion of C-PNT aims at building a larger European PNT ecosystem to mitigate the risk of PNT service interruption, which includes GNSS and several complementary emerging alternative systems.

Research shall address the different options for time synchronisation (in particular during GNSS outages). On this point, there is on-going work performed by MIAR SESAR solution 0336 “LDACS-NAV solution & Modular Integration of A-PNT technologies solution”.

This research element covers A-PNT that has both an aircraft and a ground component, including, but not restricted to: Enhanced DME for TMA: Aircraft navigate primarily using satellite-based signals, supported by ground-based infrastructure where needed. A prolonged outage of GNSS constellations has the potential to limit the ability of aircraft to take advantage of precise PBN procedures, impacting flight efficiency and airspace capacity.

Research aims at developing alternative position, navigation, and timing (A-PNT) as a technical enabler to support PBN/RNP operations in case of extended GNSS degradation or outage. Research shall develop an enhanced distance measuring equipment (eDME) with capability to support more stringent A-PNT requirements. The technology is based on a coupling of the on-board interrogator and ground-based transponder equipment to provide a smooth and seamless implementation path and improved frequency band usage. The eDME equipment is expected to support more stringent RNP and improve spectrum efficiency, for example reducing L-band congestion. It anticipates minimum change to the on-board and ground hardware.

The proposed solution shall introduce, in addition to the actual range capability (interrogation-reply), a pseudo-ranging (one way ranging), and ensure that the additional capability is fully backward compatible to support seamless deployment.

• Mode N A-PNT: Mode N is a ground-based system based on secondary surveillance radar signal formats that provides an A-PNT capability to backup global navigation satellite systems while retaining legacy distance-measuring equipment (DME) functionality. Mode N aims at delivering maximum spectrum efficiency combined with backward compatibility with legacy systems. Compatibility with military systems needs to be guaranteed. Since Mode N provides the opportunity to release a significant part of the L-Band frequencies currently occupied by DME and TACAN. The interoperability of Mode N is ensured by utilizing L-Band frequencies which are currently not used by DME on a global basis (although are used by military systems and spectrum compatibility needs to be guaranteed).
• A-PNT for vertical navigation to address use cases applicable if moving to a geometric height environment.
• Study reliance on TACAN as a means of A-PNT to support military compliance to NAV requirements.

Other technologies may be under scope, provided that they meet accuracy, availability, continuity, and integrity requirements.