The Federal Communications Commission is embarking on a novel spectrum-sharing regime as it prepares to roll out Citizens Broadband Radio Service (CBRS) spectrum in the 3.5 GHz band. K.C. Halm and Van Bloys, attorneys at Davis Wright Tremaine, detailed this spectrum-sharing plan and other rules recently put forth by the commission to govern use of the CBRS band in a webinar hosted by WIA last week.
The CBRS band includes 150 megahertz of contiguous spectrum from 3.55 to 3.7 GHz that the FCC will make available for commercial use. Both licensed and unlicensed users will have access to the spectrum for applications ranging from industrial IoT applications, to last-mile fixed access solutions to expansion of small cell capability for mobile LTE. In-building densification solutions, neutral-host venue networks and rural connectivity are other potential use cases.
Several WIA members are among the earliest users in the band. Experimental licenses have been granted to SBA Communications to test CBRS for indoor use in Boca Raton, Florida; to ExteNet Systems to test fixed wireless CBRS use for Wireless Internet Service Providers and CBRS for indoor neutral-host DAS; to Boingo, which has deployed CBRS for Private LTE at Dallas Love Field Airport; and to Verizon, which is working with Nokia, Ericsson, Google, Qualcomm, Corning and Federated Wireless to test LTE-A on CBRS at its Irving, Texas, facility.
The band currently is used primarily by the U.S. Navy for radar communications. Other incumbents in the band include fixed satellite stations and wireless ISPs. These incumbents will continue to have priority access over all other users. However, where the spectrum is unused or underutilized, the FCC will allow new licensed and unlicensed entities to use the spectrum, with access to the band managed by a dynamic frequency selection process.
“It makes sense that the FCC should bring spectrum into the sharing economy,” Halm told webinar attendees. “When you think about it, the largest transportation company in the world – Uber – owns no vehicles, and the largest real estate company in the world – Airbnb – owns no property. But the genius of both companies and other companies in those spaces is that they have found a way to marry demand with underutilized supply. They’ve identified underutilized physical assets that can be better leveraged to address demand through sophisticated algorithms and databases. And the FCC thought, why not do that with spectrum?”
To facilitate sharing, the FCC created three tiers of users that will have access to the CBRS band. Incumbent users, primarily the Navy, will have the top priority in the band.
Priority Access Licensees, which will be assigned via auction likely next year or in 2020, will have priority secondary to the incumbent users. The licenses will be split into seven 10-megahertz channels, and licensees will have priority over the third tier of users. Licenses will be capped at no more than 40 megahertz per licensee in each market.
In its October CBRS rulemaking, the FCC changed the PAL license areas from census tracts to counties and extended the license terms from three years to 10 years. PAL licensees also will be allowed to partition and disaggregate their licenses in order to sell or lease them on the secondary market, a substantial opportunity for companies to acquire licenses and sell or lease what they won’t use or to acquire spectrum on the secondary market without going through the license process, Halm said.
General Authorized Access users, which can access the spectrum on an opportunistic basis, will have access to 80 megahertz of spectrum in every market as well as the 70 megahertz of PAL spectrum when it is not being used. These users must defer to incumbent and PAL users. GAA spectrum could be made available by the end of the year, but more likely next year, Halm said.
Spectrum Access Systems (SAS) will coordinate use of the spectrum and ensure the entities with priority in the band are not impeded. An Environmental Sensing Capability network will assist with the dynamic allocation of spectrum to the three tiers of CBRS users by detecting Naval radar operation and alerting the SAS, which will then mediate use of the spectrum and protect the incumbent. CommScope and Google recently announced they are working together to jointly develop and operate an ESC network.
The CBRS band could become a harbinger for how spectrum will be allocated in the future. If the spectrum-sharing approach is successful, future spectrum allocations could also be offered with sharing built in to maximize the efficiency and use of a scare resource. Sharing is already being discussed for both the C-band and the 6 GHz band, Halm said.
“Spectrum is a finite resource,” said Bloys. “We aren’t making any more of it, and right now, the largest spectrum holder is the federal government, which makes spectrum for commercial use limited.”