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CBRS Spectrum: A Potential Boon To Community Broadband
Recent federal government efforts to expand use of public Citizens Broadband Radio Service (CBRS) spectrum could be of significant help to municipalities and local communities looking to bridge the digital divide with the increasingly popular wireless technology.
CBRS spectrum refers to 150 MHz of spectrum in the 3.5 GHz band. In 2015, the FCC adopted rules for shared commercial use of the band, creating a three-tiered structure to avoid interference with military radar during collaborative use of the spectrum.
For municipalities, the spectrum has already proven to be a valuable way to deploy wireless access to the public. In Syracuse, New York, the city last fall launched a new public wireless network on the back of CRBS. In Longmont, Colorado, the St. Vrain Valley School District used CBRS to build a private LTE network connecting 4,000 students in partnership with NextLight, which operates Longmont's city-owned municipal fiber network.
Not all community deployments of CRBS have delivered satisfactory results for municipalities, however. The STEM Alliance in Westchester County, New York retired their efforts to deploy a CBRS network in Yonkers after they struggled with urban capacity constraints and low usage.
But last month, CBRS got another major boost with the FCC announcement of new rules that should expand access to the band to an additional 72 million Americans scattered across a dozen states.
“Today, we are improving access to the 3.5GHz band for tens of millions of Americans," said FCC Chairwoman Jessica Rosenworcel in a statement. "The CBRS dynamic spectrum sharing framework is already fertile ground for wireless innovation, and through collaboration with Department of Defense, NTIA and stakeholders, we are expanding opportunities for reliable spectrum access while also ensuring that federal incumbents remain protected."
The NTIA, the U.S. Navy and the FCC have all been working in concert over the last decade to expand public access to the bands while protecting legacy users of the spectrum – largely Navy radar installations – from interference.
Commercial use of the band has historically been prohibited via Dynamic Protection Areas (DPAs) in regions where the spectrum is used by military operations. While those restrictions still exist, the FCC’s new rules should both expand those geographic protection zones–and allow for potential expansion of CRBS-based services outside of the contiguous U.S.
Putting The Spectrum To Work
Historically, communities or organizations looking to deploy private LTE or 5G networks needed to acquire spectrum, which usually involved leasing it from a carrier or directly from the government. That’s not only expensive, but often difficult given the way politically-powerful providers often dominate spectrum auctions. Enter CBRS.
The FCC’s CBRS rules utilize a three-tiered access system: incumbent access, usually reserved to military and government use of the spectrum; Priority Access Licenses (PAL), which the FCC auctions off for exclusive use in specific geographic areas; and General Authorized Access (GAA), which allows shared, dynamic use of the remaining spectrum.
Municipalities have largely taken advantage of the GAA tier, which is managed by a Spectrum Access System (SAS) designed to prevent users from causing interference. Municipalities can bid for priority access licenses, though winning auction bids can prove cost prohibitive.
Experts say the continued expansion of the band should be a significant boon to numerous underserved regions where a lack of access – or a lack of broadband competition – have left communities disconnected.
“CBRS is being deployed,” Harold Feld, a wireless spectrum policy expert and Senior Vice President for Public Knowledge told ILSR. “Tribal deployments are heavily reliant on CBRS. The changes adopted by the DoD and eventually adopted by the FCC will provide greater utility.”
The Tohono tribal community, roughly an hour away from Tucson, Arizona, has leveraged CBRS to expand broadband access to 28,000 residents, thanks in part to 2021 Coronavirus relief legislation. That network utilizes the 2.5 GHz spectrum in LTE Band 41 and is using CBRS in to expand network capacity across the reservation using CBRS in Band 48.
According to NTIA data current as of January 1, 2023, the SAS was tracking 287,033 active CBRS devices (or CSBDs) transmitting across the U.S., with more than 70% of those devices in rural areas. According to data from the Open Technology Institute (OTI), 1,000 CBRS operators have deployed nearly 400,000 broadband access points nationwide.
In a recent announcement, the NTIA noted that expanding the SAS parameters and shrinking spectrum protection zones (which should be accomplished after further FCC testing) should be a looming boon to residents in 17 states in particular.
“The innovative approach of the Citizens Broadband Radio Service is a win-win: The Department of Defense has the airwaves it needs to carry out crucial missions while providing greater access for commercial 5G and high-speed Internet deployment,” NTIA Administrator Alan Davidson said of the changes.
Grumbling Among Wireless Giants And Next Steps
Incumbent wireless giants, keen to exclusively own ever-dwindling stockpiles of valuable spectrum for both financial and anti-competitive reasons, haven’t always looked kindly on the government’s CBRS efforts.
The Cellular Telecommunications Industry Association, a lobbying and policy group representing companies like AT&T and Verizon, has been particularly critical. In 2022, the organization hired Recon Analytics to produce a study effectively claiming CBRS efforts had been a failure.
“A review of today’s CBRS marketplace shows that CBRS does not live up to the hype as the foundation of innovation and should not be a model for future spectrum policy,” said Roger Entner, Founder and Lead Analyst, Recon Analytics. “Real-world studies show low utilization, low market demand, and a dearth of innovative use cases.”
Wireless experts and consumer groups have been quick to disagree, noting that the opposition by large carriers is primarily self-serving, and that CBRS’ potential is only just starting to unfold.
“The idea that CBRS is a ‘failure’ is a self-serving CTIA narrative to assist in their spectrum grab for the lower 3 GHz band,” Feld said. “It has no basis in reality.”
The OTI, which has dubbed recent CBRS rule changes CBRS 2.0, indicates that until now, very conservative rules were adopted to minimize the risk of interference to Naval radar.
As these Dynamic Protection Areas along coastlines and around federal facilities become less strict, CBRS’ full impact should become more obvious.
“There needs to be more discussion (and action) to move this kind of shared management system to other bands,” Feld said. “The FCC has been considering it in their notice of proposed rulemaking on the 12 GHz and 13 GHz satellite bands. Additionally, there is continuing talk with DoD of extending this kind of sharing mechanism to other military bands. But so far, this has not advanced.”
The CBRS mid-band spectrum provides the optimum mixture of speed and coverage for wireless communications, and the shared nature of the FCC’s rules for the band allow municipalities to deliver less expensive networks over collaboratively-managed spectrum.
That’s of great interest not just to municipalities, but companies like Amazon, Aircell, Federated Wireless, and Dish Network, which are all contemplating cellular and fixed wireless projects in the band across the continental U.S.
*This story has been updated to note NextLight's partnership role in the building of the St. Vrain Valley School District private LTE network
Header image of cell towers courtesy of Pexels
Inline image of CBRS spectrum access tiers courtesy of ResearchGate
Debate tablet courtesy of Pix4Free