Digital infrastructure investment firm Grain Management announced on October 8 that it has signed a definitive agreement to sell all of its nationwide US 800MHz spectrum assets to SpaceX. These low-band resources will be used to support Starlink Mobile's terrestrial mobile communications and direct-to-satellite services.

The transaction amount was not disclosed, and the closing remains subject to approval by the US Federal Communications Commission (FCC) and the satisfaction of other customary conditions.

Adding low-band coverage, targeting indoor communications

The deal involves up to 14MHz of paired spectrum within the 800MHz band. SpaceX stated that these low-band resources will complement Starlink Mobile's 2GHz mid-band spectrum: the 2GHz spectrum handles higher bandwidth capacity, while the 800MHz spectrum provides a coverage layer, leveraging its propagation and building penetration characteristics to improve user connectivity in indoor and other scenarios. The company noted that most existing mobile devices already support this band.

Grain previously stated that this spectrum can use standard mobile communication protocols and is compatible with existing terminals, making it suitable for enterprise communications, private wireless networks for critical infrastructure, and next-generation direct-to-satellite services.

SpaceX's proposed service goal is to combine satellite and terrestrial networks to provide connectivity indoors, outdoors, and in areas lacking traditional cellular coverage. The above coverage effects are the company's deployment targets; what has been announced so far is the spectrum acquisition agreement.

Ground base stations and satellite authorization advancing in parallel

SpaceX's transaction application documents further disclose the terrestrial deployment plan: the company plans to use standards-compliant wireless equipment to install sector antennas on communication towers, rooftops, and other facilities to provide mobile broadband coverage.

On the satellite side, SpaceX stated that it is simultaneously seeking to modify its recently approved next-generation Starlink Mobile satellite system authorization to add the 800MHz band to the frequency range that can be used for "satellite supplemental coverage." The transfer of spectrum control and the satellite's use of this band each involve corresponding regulatory procedures.

Prior to the announcement of this acquisition, the FCC had approved SpaceX to deploy 15,000 satellites for direct-to-satellite services. The Starlink Mobile system is a different system from the Starlink constellation that provides broadband internet access to user terminals.

Spectrum transferred from T-Mobile to Grain two months ago

These assets were transferred from T-Mobile to Grain in August of this year. Grain announced the completion of the acquisition on August 11 and disclosed that the previous transaction consideration included cash and the 600MHz spectrum it held. About two months later, Grain signed an agreement to sell the entire nationwide 800MHz portfolio to SpaceX.

Grain stated that when the FCC previously approved its acquisition, it had established a competitive selection process and a path for conditionally conducting direct-to-satellite deployment.

According to the terrestrial network benchmarks listed in SpaceX's application documents, each licensed area must cover at least 33% of the population or 25% of the geographic area by July 1, 2029, and reach at least 66% of the population or 50% of the area by July 1, 2034. The documents also note that eligible license holders may choose alternative performance standards for direct-to-satellite services, adopting corresponding deployment methods in different licensed areas.