UK SPF Cluster 4 workshop: GEO, LEO and the future of EPFD
The UK Spectrum Policy Forum's Cluster 4 workshop brought together regulators, satellite operators, trade associations and simulation specialists from the UK, France, the US and beyond to debate whether, and how, to update the Equivalent Power Flux Density (EPFD) limits that govern services between geostationary (GSO) and non-geostationary (NGSO) satellite systems. The session offered a cross-section of perspectives on a debate that will shape decisions at the World Radiocommunication Conference in 2027 (WRC-27).
The workshop made clear this is no longer a simple contest between "GSO incumbents" and "NGSO newcomers." Several operators now run both types of constellation, and the discussion repeatedly returned to the idea that the old framing of two opposing camps is increasingly out of date.
Why EPFD is back on the agenda
EPFD limits were set in the late 1990s and early 2000s to protect GSO satellite links from interference generated by NGSO constellations, at a time when large NGSO systems were still theoretical. WRC-23 tasked the ITU's Working Party 4A with studying whether those limits remain fit for purpose, without committing to any regulatory change, and instructed it to report back at WRC-27.
Since then, the picture has shifted substantially. NGSO constellations have moved from theory to large-scale commercial deployment, and several administrations and operators have submitted studies arguing that today's limits carry more protective margin than is actually needed, particularly in the Ka band. Presenters flagged specific issues under review:
- whether the reference links used to derive the limits still reflect real-world GSO operations,
- whether adaptive coding and modulation (ACM) should factor into protection criteria, and
- whether the compliance-checking methodology contains outdated or overly conservative assumptions.
Where the debate splits
Some argued that the case for relaxing limits in the Ka band is now well evidenced, while the Ku band case is more complex because the underlying reference links there remain representative of systems still in operation today. Others pointed to a comparison with the coordination arc used between GSO systems as evidence that current EPFD limits allow only a fraction of the interference typically judged acceptable, arguing this makes updated limits both feasible and overdue.
A recurring theme was the distinction between changing the numerical limits themselves and changing the methodology used to verify compliance with them. Several speakers noted that the compliance-checking recommendation has already been improved in later versions not yet adopted for regulatory use, and that closing this gap could relieve NGSO operators without renegotiating the headline limits at all. One participant floated a staged approach to hold the limits steady near-term while updating the underlying verification assumptions, leaving a fuller review for a later conference.
Questions of process, and questions of pace
A significant part of the discussion focused on timing. Some presenters were confident that outstanding technical questions, including how to treat ACM, could be resolved before WRC-27; others were more cautious, noting that a packed conference agenda and the complexity of remaining issues make that a stretch. One regulator suggested a two-stage approach, making targeted and well-evidenced changes in 2027 while leaving more fundamental, structural questions to a possible agenda item in 2031.
Beyond the headline debate, participants also touched on how aggregate interference from multiple NGSO systems should be assessed, a comparable framework already used in satellite navigation bands that is now approaching its own limits, whether dynamic spectrum-sharing could ease pressure on fixed limits, and the practical difficulty of getting operators to coordinate directly given how commercially sensitive operational data can be.
What is clear is that the studies mandated at WRC-23 have moved from abstract technical debate to a live policy question with real commercial stakes, and that resolving it will require reconciling different national approaches, different technical starting assumptions, and different appetites for reform, all within a tightening timetable ahead of WRC-27.
UK SPF Cluster Workshop Ofcom
UK SPF Cluster Workshop ANFR presentation
Sophie Greaves
Sophie Greaves
Sophie Greaves is Associate Director for Digital Infrastructure at techUK, overseeing the Telecoms Programme, the Data Centres Programme, and the UK Spectrum Policy Forum.
Sophie leads our work across telecoms networks, security and resilience, supply chain diversification, advanced communications technologies, spectrum policy, and data centres - bringing these areas together into a dedicated Digital Infrastructure unit. She was previously Head of Telecoms and Spectrum Policy.
Prior to joining techUK, Sophie completed a masters in Film Studies at University College London; her dissertation examined US telecoms policy relating to net neutrality and content distribution.
- Email:
- [email protected]
- Phone:
- 0207 331 2038
- LinkedIn:
- https://www.linkedin.com/in/sophiegreaves/,https://www.linkedin.com/in/sophiegreaves/
Tales Gaspar
Tales Gaspar
Tales has a background in law and economics, with previous experience in the regulation of new technologies and infrastructure.
In the UK and Europe, he offered consultancy on intellectual property rights of cellular and IoT technologies and on the regulatory procedures at the ITU as a Global Fellow at the European Space Policy Institute (ESPI).
Tales has an LL.M in Law and Business by the Getulio Vargas Foundation (FGV) and an MSc in Regulation at the London School of Economics, with a specialization in Government and Law.
- Email:
- [email protected]
- Phone:
- +44 (0) 0207 331 2000
- Website:
- www.techUK.org
- LinkedIn:
- www.linkedin.com/in/talesngaspar
Tales Gaspar
Tales has a background in law and economics, with previous experience in the regulation of new technologies and infrastructure.
Sophie Greaves
Sophie Greaves is Associate Director for Digital Infrastructure at techUK, overseeing the Telecoms Programme, the Data Centres Programme, and the UK Spectrum Policy Forum.
