Radio spectrum is a vital for safe, efficient and cost-efficient air transport, and in particular for enabling the provision of communications, navigation and surveillance (CNS). During a dedicated session on 8 March at the World ATM Congress, the SESAR Joint Undertaking gathered experts in the field to provide an overview of key SESAR solutions that optimise the use of spectrum and to unveil the SESAR vision and strategy to create a sustainable environment for spectrum efficient aeronautical systems.

Spectrum is considered critical by those in the aviation community, none more so than SESAR, which is developing advanced CNS technologies with spectrum implications. Many of these solutions aim to specifically optimise the current usage of the radio frequency, said Marouan Chida, SESAR JU, who opened the session.

In the future communications infrastructure, no single technology/system solution will be capable of meeting the growing data exchange demands, said Stéphane Tamalet, Airbus. This is where multi-link communications comes in, making use of concurrent, existing and future communications links between air and ground (such as AeroMACs, LDACs, SAT COM, etc), depending on the performance needs. Software-defined radio is also being researched since it offers a more flexible and cost effective radio receiver architecture. These technologies will ease transition to a new spectrum efficient environment, noted Mr Tamalet.

Spectrum also has implications for the quality of GNSS signals, which are increasingly deployed in air traffic management, explained Ana Bodero Alonso, ENAIRE. Given the safety criticality of ATM, there is a need to protect these signals from jamming, spoofing and other disruptions to guarantee their correct behaviour at all stages of the flight.  This matter has been the subject of in-depth analysis by SESAR members, including ENAIRE, which have made recommendations on how to mitigate such threats.

As traffic increases in Europe and worldwide, so do the number of ADS-B broadcasts, interrogations from ground surveillance radars and exchanges from the collision avoidance system, noted Stéphane Marche, Honeywell. All of this activity leads to increased frequency load and congestion, and potential safety risks. To mitigate this, SESAR members have been working an improved hybrid surveillance system which reduces the need for active interrogation. Flight trials in 2014 showed that frequency loads savings of up to 71% can be made with the solution.

In his presentation, John Mettrop, UK CAA, noted that efforts are also taken to safeguard aviation’s current and future spectrum allocation within the framework of the International Telecommunication Union (ITU) and World Radiocommunications Conference. Concluding the session, Raffi Khatcherian, Eurocontrol said that work was underway to integrate the SESAR strategy into the ICAO Handbook on Radio Frequency Spectrum Requirements for Civil Aviation Doc 9718 Vol 1 ICAO spectrum strategy, policy statements and related information.