Buried in a four-paragraph public notice released on May 28, 2026, the Federal Communications Commission's Space Bureau has reopened one of the most consequential and least understood levers in satellite spectrum policy: the geostationary-orbit (GSO) reference link. In SB Docket No. 25-157 (DA 26-467), the Bureau seeks comment on revising the set of reference links it adopted in the Modernizing Spectrum Sharing for Satellite Broadband Report and Order. The notice is short, the docket is technical, and the stakes are enormous: the reference link is the mathematical stand-in for the entire incumbent geostationary fleet that every non-geostationary (NGSO) broadband operator is legally obligated to protect.
To understand why a single set of assumed link parameters governs billions of dollars of constellation capacity, you have to understand what the reference link actually is. When the Commission allows LEO and MEO systems to share the same Ku- and Ka-band spectrum used by traditional GSO satellites, it cannot model every real geostationary network individually. Instead it defines an idealized 'reference' GSO satellite-to-earth-station link with specified antenna sizes, transmit powers, carrier bandwidths, and elevation geometries. Interference into that reference link is the yardstick. If an NGSO system's aggregate emissions would degrade the reference link beyond a defined threshold, the NGSO system is presumed to cause harmful interference and must back off.
Why the assumed numbers are the whole game
This is the part that operators on both sides watch obsessively, and it is why the document deserves more attention than its length suggests. The Bureau states plainly that 'ensuring the GSO reference links appropriately reflect typical and widespread GSO satellite operations in the United States will promote efficient spectrum sharing among today's broadband satellite systems.' That sentence contains the entire dispute. If the reference link assumes large, high-gain earth-station antennas pointed near the horizon, the protected GSO network looks fragile and NGSO operators must throttle their emissions to avoid triggering the threshold. If the reference link assumes the smaller flat-panel terminals and steeper elevation angles that characterize modern consumer broadband, the protected network looks more robust, and NGSO systems gain headroom to radiate more power and therefore deliver more throughput.
In other words, the reference link is a single dial that simultaneously sets the floor of protection for incumbent geostationary operators and the ceiling of capacity for the LEO challengers. Move it a few decibels in either direction and you have shifted competitive advantage across an entire orbital regime without ever touching a license, a power flux-density limit table, or an antenna pattern mask. That is precisely why the Space Bureau is taking comment now rather than waiting: the original reference links were fixed in the rulemaking record, and the record on what 'typical and widespread' U.S. GSO operations look like has moved since.
The CFR hook is 47 CFR Part 25, the Commission's satellite communications rules, which is where the Earth-station and space-station technical requirements live. Any revision to the reference links would flow into the equivalent power flux-density and aggregate-interference machinery that Part 25 already references for NGSO/GSO coexistence. The procedural posture is a proposed rule, with comments due 30 days after Federal Register publication and reply comments due 45 days after.
What both camps will actually argue
Expect the incumbent geostationary operators to argue for reference parameters that reflect their most sensitive deployed links, on the theory that the protection obligation exists precisely to shield real customers from real degradation. They will point to gateway earth stations and high-throughput enterprise terminals whose larger apertures and lower elevation angles make them genuinely more vulnerable to NGSO interference, and they will resist any redefinition that quietly assumes those links away.
The NGSO constellations will push the opposite direction. Their argument is that the reference link should track the realistic, statistically dominant GSO deployment, not the worst-case outlier, because over-protecting a hypothetical link wastes spectrum that could be carrying broadband to consumers. They will note that the consumer terminal population has shifted toward small electronically steered flat panels, and that the geometry of where U.S. earth stations actually point has changed. If the reference link reflects today's fleet rather than the assumptions baked in during the earlier proceeding, the sharing math becomes more permissive for them.
There is a third, quieter constituency: operators who run both GSO and NGSO assets, or who are migrating between regimes. For them the reference link is not a partisan question but a planning input, and they tend to favor whichever parameters reduce regulatory uncertainty and litigation risk, because aggregate-interference disputes are slow, expensive, and capacity-destroying for everyone.
What makes this proceeding worth tracking for anyone modeling constellation economics is that it is downstream of the larger Modernizing Spectrum Sharing for Satellite Broadband order but upstream of every future NGSO capacity projection. The reference link is an input to the interference budgets that determine how aggressively a constellation can frequency-reuse, how many beams it can light up over a market, and how much usable capacity it can sell. A revision that adds even a couple of decibels of headroom propagates through the whole link budget and ultimately into the throughput numbers operators put in front of investors.
The document itself is procedurally modest, a Bureau-level notice rather than a full Commission rulemaking, and it does not propose specific new numbers. It asks the industry to supply the evidence. That is the tell: the Bureau is signaling that it intends to update the reference links to reflect current operations, and it is inviting both sides to fight over what 'current' means before the parameters are locked back into Part 25. Anyone whose business depends on Ku- or Ka-band sharing should read the eventual comment record as the real fight, because that is where the decibels will be won and lost. The deadline is 30 days from publication, and in spectrum sharing, a 30-day window can decide a decade of capacity.