SpaceX, T-Mobile US phone service will interfere with ours, claims rival
5G mobile and satellite operator accuses Musk firm of making 'elementary errors' in its calculations
Satellite constellation operator Omnispace has written to the FCC's newly minted Space Bureau about its concerns that SpaceX and T-Mobile US's planned hybrid space-terrestrial phone service will "constantly" interfere with its own system.
SpaceX, as we reported at the time, is hoping to bring together its Starlink low Earth orbit (LEO) satellite constellation with T-Mobile's terrestrial wireless network in a scheme to provide connectivity across America.
But VC-backed Omnispace, which owns and operates global non-geostationary satellite infrastructure and is developing its own hybrid ground/space network to provide 5G and IoT services, says SpaceX's satellites will create "harmful interference" with Omnispace's receive antenna system. SpaceX reckons any such interference would be transient, but the operator fears it will be "constant," claiming that SpaceX made "elementary errors" in its calculations.
The under-the-radar satellite company (we're here all week) raised $60 million to fund the rollout of the system back in 2021.
Omnispace's system relies on 60MHz of globally licensed spectrum in the S-Band and has said its non-geostationary satellite constellation will be using 5G non-terrestrial network (NTN) tech – yes, some of the promised future 5G functionality – to expand the reach of small handheld and IoT devices.
The constellation operator's letter [PDF] to the FCC last week was a response to SpaceX's July presentation to the agency claiming the company and T-Mobile would "provide ubiquitous connectivity to millions without causing harmful interference."
The SpaceX filing also asserted that its hookup with T-Mobile – which the two are calling "Coverage Above and Beyond" – would provide "massive benefits of ubiquitous coverage to millions of American consumers through their supplemental coverage from space partnership."
In its counter-response last week, Omnispace talks about idiosyncratic uplink and downlink allocations, noting that the American terrestrial assignment system, as used by T-Mobile in the US, differs from the international mobile-satellite uplink-downlink allocation the International Telecommunication Union uses.
While this does not necessarily create problems for terrestrial infrastructure, Omnispace claims, these conflicts do "generate acute problems for satellite infrastructure where even a single distant transmitter operating at comparatively low power can cause system-disabling interference for sensitive satellite receivers" – because the vacuum of space provides the "least-possible path loss," meaning less reduction in power density than you'd hope for.
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It goes on to claim that SpaceX made an "elementary error" [sick burn – Ed] in calculating the aggregate interference of SpaceX SCS downlink into Omnispace's satellite uplink, adding: "This mistake results in the erroneous conclusion that the aggregate interference will be significantly below internal noise power."
The satellite network operator says in the letter:
SpaceX claims this is a transient problem by assuming only one Omnispace satellite out of a constellation is impacted. However, because there are two constellations of satellites (Omnispace and SpaceX) moving constantly in relation to each other, the interference issues are not a transient problem but a continual one.
Omnispace met the FCC the day before, and likewise presented a pack of slides to back up its assertions, which you can peruse here.
Gartner analyst Bill Ray told us this time last year that there are significant barriers to the SpaceX/ T-Mo project, not least that SpaceX satellites were not capable of delivering the service as StarLink had no authorization to deploy v2 satellites, "which are needed for several reasons including to run this system."
That situation changed in December last year when SpaceX received US approval to deploy up to 7,500 of its Gen2 satellites.
Omnispace, as is common in the small world of space, still has to do business with the Musk-led company to get its sats into place, having previously hitched a ride on Starlink parent SpaceX's rockets to launch its Thales Alenia Space-designed satellites to non-geostationary orbit.
The busses of the satellites were built by Nanoavionics, with the S-band communications payload built by Thales Alenia Space in conjunction with Syrlinks. The vendors said that they would, alongside other industry stakeholders, contribute to the development of the NTN friendly standard for global implementation for 3GPP, the overseer of the work on 5G radio tech and other standards.
We have asked SpaceX for comment. ®