The FCC Wants to Redefine the GSO 'Reference Link' — and the Stakes Are Billions in Shared C- and Ku-Band Spectrum

On May 28, 2026, the FCC's Space Bureau published a proposed rule that, on the surface, asks a narrow engineering question: should the Commission revise the set of geostationary-satellite reference links it adopted earlier this year? The document, filed under SB Docket No. 25-157 and carrying the identifier DA 26-467, sets comment deadlines of 30 days after publication for initial comments and 45 days for replies. Beneath the procedural language sits one of the highest-leverage parameters in modern satellite regulation — the assumption that decides how two very different classes of satellite systems share the same airwaves.

What a reference link is, and why it controls money

Geostationary (GSO) satellites sit in a fixed arc roughly 35,786 kilometers above the equator and have anchored satellite communications for decades. Non-geostationary (NGSO) systems — the low-Earth-orbit broadband constellations now scaling rapidly — sweep across the sky and, critically, can pass through the line of sight between a GSO satellite and its ground stations. When that happens, the NGSO system can raise the noise floor on the GSO link. Spectrum-sharing rules exist to cap that interference.

To write those rules, regulators need a model of what a 'typical' GSO network looks like: the assumed antenna sizes, link geometries, and performance margins of the incumbent system being protected. That model is the reference link. It is, in effect, the yardstick against which an NGSO operator's permitted interference is measured. If the reference link is defined conservatively — assuming a fragile, low-margin GSO link — incumbents get more protection and NGSO entrants are held to tighter limits, constraining the spectrum they can exploit. If the reference link is defined to reflect robust, modern GSO operations, NGSO systems gain more room. The same band, the same physics, but a different commercial split depending on where this assumption is set.

Why the Bureau is reopening it now

The Bureau's stated purpose, in the abstract of the proposed rule, is 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.' In plain terms, the reference links adopted in the Modernizing Spectrum Sharing for Satellite Broadband Report and Order may not match how GSO networks are actually built and operated today. The Bureau is asking industry to supply data on real-world GSO link characteristics so the protection assumptions track reality rather than a dated or idealized template.

This is a notable sequencing point. The Commission adopted the underlying order, then almost immediately opened a follow-on proceeding to refine one of its core technical inputs. That is a signal that the reference-link values were contested, that the record on 'typical' GSO operations was thin, or both. For market participants, it means the spectrum-sharing settlement is not final; the most consequential number is back in play, and the comment record filed in SB Docket 25-157 will shape it.

The two camps, and what each is fighting for

Incumbent GSO operators — the established fixed-satellite-service players whose business models depend on reliable C-, Ku-, and Ka-band links — have an interest in reference links that reflect demanding, high-availability operations, because that maximizes the interference protection they receive and preserves the value of their existing networks and customer commitments. Any loosening of protection translates, in their view, into degraded service quality or the need for costly mitigation.

NGSO broadband operators — the LEO constellations seeking to deliver low-latency, high-throughput service at scale — have the opposite interest. Reference links calibrated to modern, resilient GSO systems imply those incumbents need less artificial protection, freeing NGSO systems to operate at higher power or with looser geometric constraints, which directly increases the capacity and coverage they can monetize. For a constellation operator, every decibel of permitted interference is throughput, and throughput is revenue per satellite. With multiple NGSO systems competing for a finite number of usable bands, that marginal decibel compounds across an entire fleet and an entire deployment timeline.

The asymmetry of the fight is worth naming. Incumbent GSO operators are defending revenue they already book against customers under contract; NGSO entrants are arguing over capacity they have not yet sold but have already priced into their capital plans. That difference shapes how each side frames 'typical' operations — incumbents toward worst-case fragility that justifies protection, entrants toward modern resilience that justifies access. The Bureau's request for real operational data is, in part, an attempt to cut through that framing with evidence rather than advocacy.

Reading this as a business story

It is tempting to file a proceeding like this under 'engineering minutiae.' That would be a mistake. The reference link is the regulatory hinge on which the GSO-versus-NGSO spectrum balance turns, and that balance allocates economic value between two multi-billion-dollar industry segments. The Commission is not redrawing band plans or auctioning licenses here; it is adjusting an assumption. But because that assumption sits inside the interference math that gates real operations, a modest revision can shift competitive advantage without a dollar changing hands at the FCC.

A few cautions on the record as it stands. This is a proposed rule seeking comment, not a decision — no new reference-link values have been adopted, and the Bureau has explicitly invited data rather than announced an outcome. The proceeding is also bounded: it revisits the reference links from the recent order, not the broader architecture of satellite-broadband spectrum sharing. And the practical impact will depend entirely on the quality and volume of operational data that GSO and NGSO operators put into SB Docket 25-157, because the Bureau has asked, in effect, to be shown what 'typical' really looks like.

For analysts and corporate-development teams tracking the satellite-broadband market, the action item is simple: watch the comment filings. The parties that successfully define 'typical and widespread GSO operations' will, in a real sense, be defining how much of a shared band their competitors are allowed to use. That is the kind of fight that does not make headlines but quietly reorders a market.