With proposed rulemaking, FCC looks to open higher reaches of spectrum for services just coming into view
The FCC wants to take us higher: into higher reaches of the RF spectrum. Anticipating the eventual arrival of Fifth Generation (5G) mobile services, the FCC has proposed to open several bands above 24 GHz for 5G: 28, 37, and 39 GHz, and possibly 24, 29, 31, and 42 GHz as well. Also on the table: extending the 57-64 GHz unlicensed band up to 71 GHz, and adding mobile applications to the 71-76 and 81-86 GHz fixed service bands.
The FCC is under pressure to keep the U.S. wireless industry competitive. A 5G standard would be significantly faster than 4G and able to handle many times the volume of traffic. A year ago, the FCC began to look at the issues with a Notice of Inquiry. Now it’s released a new Notice of Proposed Rulemaking (NPRM) which aims at establishing several sets of rules for various potential users, including fixed, mobile, satellite, and “WiGig,” a high-speed unlicensed standard at 57-64 GHz modeled in some respects on Wi-Fi.
The proceeding, titled “FCC Promotes Higher Frequency Spectrum for Future Wireless Technology,” focuses on opening the “upper microwave” bands (here, 28 GHz, 37 GHz and 39 GHz) for more flexible use, including 5G hotspots. The FCC hopes this will lead to deployment of small cells and Wi-Fi-like networks for data backhaul, as well as privately deployed (enterprise) networks.
The NPRM ducks the question as to whether, or how soon, these high frequencies could actually be used for mobile applications. Today, after all, the term “5G” is little more than a marketing slogan. The operating characteristics of 5G technologies are unknown. There are no agreed-upon technical standards, and none are expected for at least a few years (according to Commissioner Pai, not until at least 2020). Still, given how long it takes to allocate spectrum, adopt licensing and service rules, and conduct auctions, the FCC is wise to take a “build it and they will come” approach.
Some of the bands under discussion have an unhappy history in terms of getting the spectrum into actual use, particularly 28, 31, 39 and 24 GHz. Each of these bands offered licenses that covered a specific geographic area within which the licensee could provide fixed microwave service for itself or sell service to others. The FCC auctioned 28 and 31 GHz together in 1998-99 for $624 million, and 39 GHz in 2000 for a respectable $411 million. By the time of the 24 GHz auction in 2004, investors had become wary: they bought only seven licenses out of 880 offered, for a paltry $216k.
To encourage successful bidders to build and operate their systems promptly, the FCC required the licensee to construct facilities and offer “substantial service” within 10 years. But equipment proved difficult to procure and markets proved slow to develop. As a result, most licenses did not get built out, and their licensees requested and received multi-year extensions. The FCC supplemented its vague “substantial service” requirement with a “safe harbor” option, but that didn’t help: holders of a large majority of licenses still failed to meet the extended deadlines. Ultimately, the FCC rejected further extensions and refused renewals, in effect taking back the licenses. (One affected provider has since recovered at least some of its licenses in a court proceeding.) On the whole, the FCC’s denial of renewals brought about precisely the result the FCC had sought to avoid: large swaths of unused spectrum.
This NPRM is a “Take 2” effort to put the same frequencies to productive use.
The main difference between the mostly-failed earlier regime and the one proposed here is the addition of mobile services. Existing mobile applications, such as 3G and 4G, use much lower frequencies (below about 3.5 GHz, with the sweet spot at 0.5-2 GHz). Mobile operation above 24 GHz faces new technical and economic hurdles. Radio waves at these frequencies travel in short, straight lines and do not easily penetrate obstacles, including many types of exterior building walls. Outdoor service will need cell sites at least every few blocks. Indoor service in a typical office district will need cell sites inside every building, and because the concrete between stories will severely attenuate the signals, perhaps several on each floor. For Internet service, each of these sites must somehow be connected back to the carrier’s facilities. None of this is impossible, but it will likely prove to be much more difficult expensive than building out a conventional 4G network.
Below is a brief summary of the proposals, with the usual caveat: those interested should take a close look at the NPRM.
37 GHz Band. The Commission proposes hybrid rules for mobile operations in this band: first, for wide area networks, an auctioned geographic licensing scheme, and second, for local area networks, a “license by rule” arrangement designed to allow private industrial or enterprise networks to serve both indoor locations and, possibly, outdoors on a campus or similar facility. (The “license by rule” approach, first used for CB radios, is a legal fiction that simply declares qualified users to be licensed. Congress has okayed this to end-run the Communications Act requirement that all radio operation be licensed. “License by rule” does not extend to so-called “unlicensed” transmitters like Wi-Fi and Bluetooth, which the FCC has, with court approval, long exempted from licensing requirements on the ground that they lack significant potential to cause harmful interference.) The FCC seeks comment on how the hybrid licensing approach should work, the proposed band plan, build-out milestones, and foreign ownership.
28 GHz and 39 GHz Bands. The FCC proposes to authorize mobile services for these bands under its traditional geographic area licensing scheme. It would add mobile authorizations to existing licenses, and, through competitive bidding, assign new licenses that can used for both fixed and mobile operations. As with the 37 GHz band, the Commission seeks comment on such issues as the size of the license areas, the treatment of current licensees, and the proposed band plan. The Commission also is considering a Spectrum Access System similar to that adopted for the 3.5 GHz band to manage the various users, including satellite operators.
64-71 GHz. The FCC proposes to open this band, adjacent to the existing 57-64 GHz unlicensed band, for unlicensed use under similar technical rules. Due to a quirk of physics, however, the newly added spectrum will be much more useful. Oxygen molecules in the air absorb energy at 57-64 GHz. To a 60 GHz radio wave, ordinary air looks like a dense fog that blocks 98% of the energy per kilometer covered. Perhaps in part to compensate for these losses, rules for the present 57-64 GHz band allow a very high (for unlicensed) effective power of 158 kilowatts, if the operator uses a highly directional antenna. But the oxygen effect is greatly reduced in the adjacent 64-71 GHz segment, especially at the upper end, so the high transmitter power available should permit transmission of greater volumes of data over longer distances in that segment.
Satellite. The satellite industry did not fare well in the NPRM. The FCC rejected the proposition that mobile broadband is incompatible with the satellite use, and also found that there are no current commercial satellite operations or even concrete plans to offer satellite services in the 28, 37, and 39 GHz bands. The FCC did propose that fixed satellite operators could acquire 28 GHz flexible-use terrestrial licenses to obtain co-primary status for gateway earth stations.
Other bands. The FCC also invited comments on (but did not propose service rules for) the 24, 29, 31, 32, and 42 GHz bands, plus a possible mobile allocation in the 71-76 and 81-86 GHz fixed service bands. Commissioners Pai and O’Rielly both dissented to the NPRM in part on the ground that it does not open a sufficient number of frequency bands.
If you have a great technology that you’d like to operate above 24 GHz, now is the time to tell the FCC. Comments are due by January 26, 2016, and reply comments by February 23. File at this FCC website using Proceeding Number 14-177.