Why It Matters
Geostationary satellite operators in the United States and the broadband satellite systems that share spectrum with them will work from a revised set of reference links, the Federal Communications Commission's Space Bureau has decided.
The final action takes effect Dec. 7, before the Commission's new sharing framework has been implemented. The links set what non-geostationary orbit (NGSO) systems must protect.
The Bureau says that "the services available to consumers across the United States from fast-growing NGSO systems will be limited by the NGSO operational parameters necessary to protect the most sensitive link in the geostationary orbit (GSO) reference link dataset."
The Broader Context
The update changes the initial set of 328 reference links adopted in the Commission's "Modernizing Spectrum Sharing for Satellite Broadband Report and Order" on April 30.
The Space Bureau says the revised links will "appropriately reflect typical and widespread GSO satellite operations in the United States," which "will promote efficient spectrum sharing among today's broadband satellite systems."
That order replaced a regime built on equivalent power-flux density limits developed in the 1990s, which the Commission had concluded was "spectrally inefficient and overprotective of modern GSO networks."
Under the order's alternative framework, a non-geostationary operator can certify a completed coordination agreement with co-frequency geostationary operators or submit a compatibility showing that uses the reference link dataset.
The update does four things:
- Adds links proposed by geostationary operators and by one non-geostationary operator, SpaceX, for the 17.3-18.6 GHz and 19.7-20.2 GHz bands.
- Removes links for operations outside the United States, links tied to no current operator, and links for networks that "never began operations or ceased operations over a decade ago."
- Adopts a 9.5 dB carrier-to-noise ceiling for user terminal links that do not use adaptive coding and modulation. Links above it are revised downward or removed.
- Corrects Hispasat link parameters and strips extraneous columns from the dataset.
Commenters flagged links in the initial dataset with carrier-to-noise levels "of up to 18 dB." DIRECTV said such thresholds "are not reflective of non-Adaptive Coding and Modulation (ACM) operations." SpaceX proposed the 9.5 dB ceiling, and DIRECTV supported it for broadcasting-satellite service user links.
SES objected. It said some of its geostationary media distribution services use non-adaptive links with a 12.6 dB threshold "to maximize link capacity." The Bureau declined to accommodate that, saying "higher Carrier-to-Noise Ratio (C/N) values appear to be relative outliers on older networks." It called 9.5 dB "a reasonable upper bound for modern, widespread and typical non-ACM user terminal links."
The Bottom Line
The Bureau says it "will consider in particular any real-world operational information once the new rules are effective" before it reassesses protection criteria. It also says "operating NGSO systems may be required to adjust their operations to protect any new GSO reference links added in the future."
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