The Federal Communications Commission dealt Dish a major blow, saying its 5G plans posed “a significant risk of harmful interference” to satellite internet.

Starlink relies on spectrum in the 12GHz band for the downlink between its satellites and ground stations. Dish’s 5G plans involved using spectrum in the same range to power its network, a move Starlink says would cause enough interference to render its service “unusable.”

It seems the FCC agrees with Starlink, ruling 4-0 that Dish cannot use the spectrum. The draft order also emphasized the FCC’s desire to protect the incumbent’s investment, as well as its progress toward closing the digital divide.

In the 12.2 GHz band Report and Order, we find that authorizing two-way, high powered terrestrial mobile service in the 12.2 GHz band would impose a significant risk of harmful interference to existing and emergent services in the band, including satellite services. Such interference could undermine investments made by incumbent licensees and jeopardize their potential to provide new services to underserved communities, including rural communities.

FCC Commissioner Nathan Simington voiced his approval of the decision, as well as the reasoning behind it:

I am happy to support today’s item. The Report and Order makes the right policy call by protecting NGSO FSS incumbents who have engaged in significant investment in the 12.2 to 12.7 GHz band. The Report and Order also gets the engineering right, considering both these same incumbents’ on-going deployment of state-of-the-art satellite technology and overall trends in earth station design and regulation.

Today’s NGSO FSS satellites speak to arrays of electronically steered receivers. Signal rejection within those receivers is frequently achieved very close to the desired reception angle with arrays composed of antennas of limited dynamic range. The power levels and coverage profiles of terrestrial networks risk saturating such arrays with interference from networks of powerful terrestrial transmitters, including via side lobes even when care is taken with terrestrial antenna angles. Barring significant technology developments driving down the price and complexity of individual array elements while driving up quality, this will probably be the case for some time to come. And unless and until we see terrestrial technologies deployed in real-world situations, the FCC has no business betting the store on them by undermining the viability of fixed incumbent services in active deployment at large scale for which there is significant demonstrated public demand.

The FCC’s decision should go a long way toward helping Starlink continue its growth and serve its customers.