A lot of industry folks may think of the embedded subscriber identity module, or eSIM, when the term comes up. But there’s a similar sounding acronym – ESIM – that has an entirely different meaning for wireless networks.
In this case, ESIMs refer to earth stations in motion, and according to the FCC, they offer the potential to vastly improve connectivity for Americans on the move – when they presumably start moving again by land, sea and air, en masse, after the pandemic.
In May, the FCC expanded the frequency bands available to ESIMs, which are part of the latest and greatest satellite systems currently being deployed. The FCC said it was advancing regulatory consistency between ESIM communication with fixed satellite service systems in geostationary satellite orbit (GEO) and those in non-geostationary satellite orbit (NGSO).
A geostationary satellite system is one that remains essentially at the same position above the earth. In the case of NGSO, there are moving parts, and that’s why Verizon and U.S. Cellular are concerned about interference with their 28 GHz operations. According to the carriers, NGSO ESIMs operating in the 28.35-28.6 GHz band pose unique interference risks to nearby terrestrial operations primarily due to their mobility. SpaceX, OneWeb, Amazon and others are deploying NGSO systems.
When the commission passed its new rules, it also started a public comment period on potential interference from out-of-band emissions (OOBE) of ESIMs operating near the wireless carriers’ spectrum, technically called Upper Microwave Flexible Use Service (UMFUS) for those eager for another acronym. That’s prompted a number of comments by Verizon, U.S. Cellular, CTIA, Amazon, the Satellite Industry Association (SIA) and others.
At the time of the FCC’s vote, Commissioner Michael O’Rielly noted that while the promise of the large NGSO constellations and ESIMs seems boundless, there was virtually no record on whether their proliferation could cause harmful interference to adjacent terrestrial wireless systems in the 28 GHz band. He supported seeking further comment on whether the commission’s OOBE rules are adequate to ensure that NGSO ESIM communications will not interfere with wireless networks, although he was disappointed the issue wasn’t in the FCC’s original notice.
Verizon, T-Mobile, AT&T and U.S. Cellular are all planning to use low, mid- and high band spectrum to support their 5G offerings. However, Verizon in particular holds the lion’s share of 28 GHz spectrum. Its current 5G strategy relies heavily on millimeter wave spectrum – Verizon spent over half a billion dollars to acquire its 27.5-28.35 GHz licenses in Auction 101. U.S. Cellular spent $129 million for its licenses; together, Verizon and U.S. Cellular accounted for nearly 90% of all payments made to the FCC during Auction 101.
Both companies previously have expressed concern about potential interference from satellite players. “Absent necessary protections, such operations could cause significant harmful interference to mobile carriers’ deployment of 5G in the adjacent 27.5-28.35 GHz band,” the carriers told the commission in a recent filing (PDF).
Verizon and U.S. Cellular also made the case for terrestrial-based wireless services. They noted that consumers rely on it more than ever, and COVID-19 has underlined the importance of wireless broadband technology, especially 5G, for post-pandemic economic recovery. Key to supporting new services is mmWave spectrum, and the 28 GHz band, in particular, offers high bandwidth, superior data transfer speeds and low latency.
Satellite industry: More restrictions unnecessary
The SIA, which represents Amazon, AT&T, the Boeing Company, OneWeb, SpaceX and many others, argues that there’s no basis for the FCC to consider a more restrictive OOBE limit for NGSO ESIMs operating in the 28.35-28.6 GHz band.
“Indeed, the differences between elevation and look angles created by ESIMs communicating with NGSO satellite systems and by GSO satellites are not significant enough to justify additional restrictions than those already in place for fixed/ubiquitous blanket-licensed terminals, which can be deployed anywhere in the U.S.,” SIA told the commission (PDF). “Accordingly, the Commission should not adopt a more restrictive OOBE limit or additional technical limitations for NGSO ESIMs” operating in the 28.35-28.5 GHz band than existed for fixed satellite services.
It’s unclear when the issue will be resolved at the FCC; Commissioner O’Rielly noted in his statement this past spring that he looked forward to an expeditious resolution.