November 14, 2019

[CNESMAG] Q&A - Alexandre Vallet

Invisible but not infinite, the radiofrequency spectrum is increasingly in demand from applications. So how is this precious resource shared? Alexandre Vallet, Chief of the space services department (SSD) at the international telecommunication union (ITU)


Alexandre Vallet Credits: © CNES/O. Pascaud, 2019

What is the role of the ITU?

Alexandre Vallet : Created in 1865 to support international telegraphy, the ITU is the United Nations specialized agency responsible for information and communication technologies (ITCs). The ITU has three sectors devoted to international telecommunication standardization, equitable development of ITCs around the world and management of radiocommunication frequencies. Its radiocommunication sector (ITU-R) comprises a study group and two departments, one for terrestrial services and one for space services—my sphere of responsibility—which registers all frequencies of orbiting satellites.

What are the radio regulations?

A.V : The Radio Regulations (RR) are a broad treaty covering all radio systems up to 3,000 GHz (mobile telephony, radar, Internet of Things, etc.) designed to prevent interference between frequencies. The treaty is negotiated by the 193 UN member states.

 It’s above all a discussion and coordination process to ensure harmonious development of current and future projects.

How are radio frequencies assigned to satellites?

A.V. : The ITU implements the regulations but authorizations are delivered by member states. What this means in practice is that when a nation plans to launch a satellite, it sends a description of it to my department at the ITU. If the request is from a private operator, it has to go through a government agency like ANFR, the French frequencies agency, which then validates the request and files it with the ITU. If the information provided complies with the treaty, we forward it to the member states, which have four months to signal any potential risk of interference with one of their operating or planned satellites. If a risk exists, the requesting nation undertakes bilateral discussions with the other states concerned to find ways of operating the satellites without interference. We then register the satellite’s final characteristics in our database so that nations can access that information when planning their future projects.

Are the current shifts we’re seeing in telecoms, especially satcoms, affecting frequency spectrum management?

A.V. : Telecommunications are increasingly present in all areas of the economy and our daily lives. Requests are coming in thick and fast for applications of all kinds, including for burgeoning satcoms activities. As a direct consequence of that, frequency bands are getting closer to one another as more and more systems use them, and existing filters are no longer able to handle the resulting overlaps. This situation makes finding available spectrum complicated in some places, requiring intense negotiations between countries and at national level. For example, it’s getting hard these days to find an orbital position for a bouquet of TV channels over Europe and Africa.


  • 2000
    Graduates from Telecom ParisTech, majoring in satcoms. Joins France Telecom R&D to work on coordination of satellite radiofrequencies.
  • 2005
    Joins Orange’s frequencies bureau, in charge of European and international regulatory matters.
  • 2007
    Head of the regulatory affairs and orbital/spectrum resources department at ANFR, the French frequencies agency.
  • 2017
    Chief of the Space Services Department (SSD) in the Radiocommunication Bureau at the International Telecommunication Union (ITU).

Are these changes spawning unprecedented situations?

A.V. : Most of all, they’re giving rise to discussions about things that weren’t really an issue before! The newest of these concerns the exploration of celestial bodies, which is now being envisioned on a larger scale, in some cases for commercial purposes. Who knows, maybe one day we’ll need a frequency plan for the Moon or Mars!

Is the advent of mega-constellations and 5G an issue?

A.V. : No, not at institutional level in any case. There are mechanisms already in place to handle these systems, the only proviso being that we’re seeing a step change, since until now the largest constellation—Iridium—only comprised 60 active satellites. With constellations of several hundred satellites, the principles are the same but computing resources need to scale up to avoid interference. So we’re adopting a ‘wait-and-see’ posture for the time being, because a lot of constellations are planned but how many of them will actually materialize?

Frequency spectrum is a finite resource. Is there a danger of it running out?

A.V. : Fortunately, we’re still a long way from that happening, even though it’s true that spectrum is close to saturation in some places where it’s used extensively. But we still have room to manoeuvre, as this issue is spurring industry to engage R&D actions to exploit higher frequencies. Recently, the European Space Agency tabled a project that would use bands at around 70 and 80 GHz, nearly eight times higher than those used by current comsats.

Could other technologies free up spectrum?

A.V. : There are laser and optical links, for which frequencies are unregulated as the risks of overlap are low. If systems were to start using them massively, some sort of coordination would no doubt be necessary. For now, the ITU is working to standardize laser links.

The issue is more about making usage more efficient than freeing spectrum.

If we look at projected data transfer requirements, we’re not going to resolve all the issues simply by adding spectrum. We also need to improve transmission techniques using modulation and encoding to squeeze more data into the same number of frequencies.

Can regulations keep pace with such rapid changes?

A.V. : The Radio Regulations are one of the few treaties that are revised on a very regular basis, every four years as it happens, to keep pace with advances in technology, yet without jeopardizing stability of use and innovation. Because operators need to know they can exploit their innovations for several years, but without stifling future advances and competing technologies.

What role does an agency like cnes have to play in guaranteeing rational spectrum use?

A.V. : As a satellite operator and space agency, CNES needs to set an example and lead the way in using spectrum as efficiently as possible, with the most advanced technologies. As the regulator of spectrum use for space science in France, it has an institutional role in ensuring maximum science return from available frequencies. Lastly, it must support academics, who in most cases are not familiar with frequency regulations, to make sure that their cubesat-type projects apply commonsense and neighbourly rules of conduct in space.