O3b throws water on idea of near-term solution for 28 GHz sharing

Saying uplink interference is an enormously complex problem, O3b told the FCC that absent serious engagement right away, it's unlikely that any solution can be developed in the near term when it comes to shared satellite and terrestrial use of the 28 GHz band.

O3bMaritime technology debuted on the
Royal Caribbean Harmony cruise ship.
(Image courtesy O3b)

Mobile operators have identified the 28 GHz band as one they're experimenting with and eyeing for 5G, but it's a band that also is home to satellite services. O3b says its system – which, by the way, is growing rapidly in markets like maritime – cannot operate without using the 28 GHz band. Specifically, the 27.6-28.4 GHz band, most of which overlaps with the LMDS "A" block, represents 60 percent of the spectrum that O3b uses for uplinks.

According to O3b's filing with the FCC, all of its gateway facilities use, and must continue to use, all of the 28 GHz frequencies on the O3b satellites. Its network operations center manages all O3b operations globally and uses the 28 GHz band to test and integrate customer terminals for deployment. O3b's U.S. gateways interconnect traffic from all of the Americas and the Pacific.

O3b, named for the "other 3 billion" and more people in the world who are unconnected, says it has "spurred a revolution" in maritime communications. On the day it initiated its maritime service to a Royal Caribbean cruise ship, that one ship instantly had more bandwidth than the rest of the global cruise industry combined, and when O3b launched service to a second Royal Caribbean ship, those two ships had more capacity than all other maritime vessels combined. "Without O3b's unique system these breakthroughs in connectivity were simply out of reach for these markets," the company said.

O3b also explained that while some spectrum sharing discussions are underway, "engagement has been uneven." In particular, developing rules that protect satellite receivers requires significant engagement by both terrestrial and satellite interests to discuss ways to control aggregate uplink interference. FCC Chairman Tom Wheeler in March essentially told the mobile and satellite industries to double down on their efforts to compromise and find spectrum sharing solutions. 

Also in March, O3b submitted its uplink interference study, which showed even relatively small numbers of terrestrial 5G transmitters could create a level of noise that would overwhelm the receivers on O3b's satellites. O3b says the FCC must not allow mobile service in the 28 GHz band absent adoption of appropriate thresholds to protect fixed satellite service (FSS) receivers from the aggregate emissions of 5G.

Meanwhile, SES Americom and Inmarsat Mobile Networks recently submitted comments that support in principle the initial framework that AT&T (NYSE: T) and EchoStar outlined to the commission on April 5, which would allow individually licensed FSS earth stations to share spectrum with terrestrial 5G operations in the 28 GHz band. Their support is contingent on some conditions, such as making sure FSS satellites receiving in the 28 GHz band are protected from the interference generated by all types of 5G transmitters located inside the uplink satellite beams.

For more:
- see this O3b filing
- see this Inmarsat filing

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