The agenda of the International Telecommunication Union (ITU) World Radiocommunication Conference of 2019 (WRC-19) contains several items that could have a severe impact on the ability of ESA’s future high data rate missions to successfully downlink data to an earth station.
The most critical agenda item is AI 1.13 dealing with the 5th generation (5G) of mobile phones, also called IMT-2020 and beyond. Under this agenda item the 25.5-27.0 GHz frequency band used by future Space Research Service (SRS) missions like EUCLID and PLATO or by future Earth Exploration-Satellite Service (EESS) missions like MTG or Copernicus evolution, the 31.8-32.3 GHz band used by SRS missions like BepiColombo and Juice, and the 37.0-38.0 GHz band planned for SRS missions going to the moon and beyond with crew on board and using the same radio below and above the deep space limit, are being considered for 5G applications. Due to the use of millimeter waves that makes global roaming not attractive, hot spots in urban and sub-urban environment with 100-m maximum cells size are envisaged. However, due to the sensitivity of SRS earth stations to interference, results indicate that in certain cases the IMT-2020 base stations have to be as much as 100 km away from the SRS station while for EESS stations this distance is of the order of 10 km. Seamless 5G roaming will instead target the 3.8 GHz band used by fixed satellites, which does not impact ESA.
Also extremely critical to ESA’s interests is AI 1.14 dealing with High Altitude Platform Systems (HAPS), a sort of Fixed Service (FS) links for which one of the stations associated with the radio link is at a 20-50 km height from the earth surface. This agenda item is also considering the use of the 25.5-27.0 GHz frequency band in the ITU region 2 (the Americas), and the use of the 38.0-39.0 GHz band adjacent to the SRS in all three ITU regions. HAPS have been conceived as natural extension of IMT-2020 base stations in scarcely populated or desert areas where deploying stations network is not economically viable or feasible. While IMT-2020 base stations are planned with 15-m height towers, the 50-km height of HAPS makes these systems visible from SRS and EESS stations at distances larger than 250 km and also creates the case for international cross border coordination (an HAPS in Chile could affect the ESA deep space station in Argentina since the platform is well above the Andes mountain range.)
The third critical item is AI 1.6 dealing with the addition of non-geostationary satellite orbit (NGSO) applications of the fixed satellite service (FSS) in the 37.5-38.5 GHz band, which partly overlaps with the SRS allocation.
In all these cases, ESA’s goal is to make sure that the protection of SRS and EESS stations reception in the above frequency bands is guaranteed by either a no change (NOC) to the ITU Radio Regulations (RR) or by regulatory provisions like coordination areas, power flux density masks, etc. associated with the new allocations.
Agenda items 1.6, 1.13 and 1.14 are not only affecting ESA’s earth stations but also the adjacent bands sensors on-board the EESS missions of the Agency due to the unwanted emissions of NGSO FSS, IMT-2020 and HAPS stations radiated towards the sky and the fact that the sensor footprint encompasses a large geographical areas on the Earth. EESS sensors are also to be protected from Radio LAN (RLAN) applications in the 5 GHz band. While the EESS passive sensors protection is outside the scope of this paper, it is important to judge the effort that the ESA Frequency Management Office has to devote to WRC-19 and all associated ITU and European preparation meetings.