The FCC is seeking comments on a bevy of issues related to spectrum bands above 24 GHz, including the addition of more bands – like 71-76 and 81-86 GHz – and how best to coordinate federal access to address information security.
The FCC on July 14 voted make more spectrum available for flexible use wireless broadband than ever before, creating a new Upper Microwave Flexible Use service in the 28 GHz (27.5-28.35 GHz), 37 GHz (37-38.6 GHz) and 39 GHz (38.6-40 GHz) bands, with an unlicensed band at 64-71 GHz.
Leading up to the vote, several commenters asked the commission to consider other bands for mobile use. CTIA and Nokia, for example, asked the commission to consider bands that don’t have 500 MHz of spectrum because certain applications might be feasible for smaller bandwidths.
“Several factors lead us to conclude that it is now appropriate to consider additional bands for mobile use,” the commission said in its Aug. 24 Federal Register submission. The commission laid out three of those factors:
- A variety of services, including fixed, mobile and satellite, could use these bands
- The World Radio Conference identified a large number of bands as candidate bands for IMT-2020, including several bands that the commission didn’t address in the Notice of Proposed Rulemaking (NPRM)
- With global mobile data traffic poised to grow nearly tenfold between 2014 and 2019, the commission figures it’s appropriate to seek comment now on most of the bands identified at the 2015 World Radio Conference
Specifically, the commission is considering the authorization of flexible use licenses to permit fixed and mobile services in the 24.25-24.45 and 24.75-25.25 GHz, 31.8-33.4 GHz, 42-42.5 GHz, 47.2-50.2 GHz, 50.4-52.6 GHz, 71-76 GHz and 81-86 GHz bands. Each of these bands was identified as a candidate band for IMT-2020, the commission said.
Except for the 71-76 GHz and 81-86 GHz bands, the FCC proposed to use geographic area licenses with Partial Economic Area (PEAs) as the license area size. For the 71-76 GHz and 81-86 GHz bands, it proposed to use a licensing framework similar to the one developed for the Citizens Broadband Radio Service (CBRS) at 3.5 GHz. For the Upper Microwave Flexible Use Service bands for which the commission adopts geographic area licensing, the commission said it has decided to conduct any spectrum auction of licenses in conformity with the general competitive bidding procedures it set forth in its Part 1 Subpart Q of its rules.
The commission said it must also consider whether the physical characteristics of the higher bands are suitable for the kinds of services that might be authorized in the bands, particularly for the millimeter wave bands where atmospheric and other environmental phenomena affect the use of the band.
Generally, atmospheric attenuation increases the higher one goes in the electromagnetic spectrum, limiting the potential length of transmission paths. However, the commission pointed out that the 71-76 and 81-86 GHz bands experience less attenuation than frequencies in the 50-60 GHz range.
The commission is in the midst of setting up a Spectrum Access System (SAS) for the 3.5 GHz band, and it’s also proposing to establish an SAS-based regulatory framework for the 71-76 and 81-86 GHz bands, where three tiers would be established.
The commission said it’s also interested in hearing more about spectrum above 95 GHz. It previously had asked for submissions about using this spectrum, but it didn't get a lot of input, possibly because everyone was focused on other areas of the NPRM. Plus, the commission figures smaller companies that are developing nascent technology above 95 GHz might not be accustomed to participating in FCC proceedings, but it still wants to hear from them about their ideas for encouraging new services and devices above 95 GHz.
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