Rosenworcel Proposes Rule Changes for CBRS Band

FCC Chairwoman Jessica Rosenworcel said Thursday that she circulated for a commissioner vote an NPRM seeking comment on further changes to rules for the citizens broadband radio service band. An FCC and NTIA agreement unveiled Wednesday on broader use of CBRS (see 2406120027) shows what's possible when you push the boundaries of how spectrum is shared, experts said Thursday during a discussion at the International Symposium on Advanced Radio Technologies (ISART) conference in Denver.

“Building on years of successful interagency collaboration,” the NPRM seeks comment on “a wide range of potential rule changes to improve” CBRS “for all current and future users,” an FCC news release said. The agency adopted initial rules in 2015, creating a three-tier model for sharing the 3.5 GHz spectrum, while protecting naval radars. The agency auctioned priority access licenses (PALs) four years ago (see 2008260055).

“Cooperation is critical for a successful spectrum future,” Rosenworcel said. “We can preserve and enhance” CBRS “to both protect progress and look ahead to further opportunities,” she said. “This proposal represents our continued commitment to developing, and improving, spectrum sharing models that provide opportunity for expanded use of the airwaves.”

Now that the Navy and NTIA have “agreed to a dramatic increase in commercial sharing of the band, we agree that the FCC should update the rules to optimize the value of CBRS” for more than 1,000 schools, businesses, utilities, factories, airports and “other diverse users who within four short years have leveraged this local access to low-power spectrum,” Michael Calabrese, director of the Wireless Future Program at New America, wrote in an email.

Calabrese expects the NPRM to focus on improving the general authorized access (GAA) tier, since “NTIA found that represents the vast majority of commercial and community use today.”

Recon Analytics’ Roger Entner, author of a 2022 report with CTIA that was critical of CBRS (see 2211140062), told us that expanding areas for spectrum use is “a huge windfall benefit” for the PALs in the middle tier, with rights superior to GAA but inferior to federal incumbents. As the Navy modernizes its carrier-born flight control radars, Entner expects the exclusion zones “to become even smaller over time.”

“More efficient use of this valuable mid-band spectrum is critical for U.S. competitiveness, especially as other countries make more spectrum available for wireless services,” Jeff Blum, EchoStar executive vice president-government and external affairs, wrote in an email.

Sharing spectrum is challenging, but the U.S. Navy goes into negotiations on any band trying to accommodate other uses, Elvira Pearce, Navy telecommunications manager, said Thursday at the ISART conference. “We never walk into a room thinking that there’s no compromise.”

As evidenced by CBRS, and the Partnering to Advance Trusted and Holistic Spectrum Solutions (PATHSS) process in the lower 3 GHz band, collaboration “has come a long way,” Pearce said. PATHSS has allowed academics and others to be part of the discussions, she said. “We’ve learned to work out ideas and … possible sharing arrangements in the early stages,” she added. “We all come to the table trying to protect our assets, so you come in cautiously.”

Policymakers are looking to “identify new ways and capabilities” that allow better sharing between commercial and government, “while still working to protect some of the sensitivities associated with those federal government uses,” said Alan Rosner, director of the Spectrum National Security Systems Program at NTIA. The effort requires creativity and hiring staff with fresh ideas, he said. Discussions like the one at ISART are also key, Rosner added.

In one of its initial paragraphs, the national spectrum strategy urges industry and government to work together on spectrum, Rosner said. “We’re doing well, we’re improving” on openness.

Kobus Van Der Merwe, professor at the University of Utah School of Computing, said discussions of sharing are more robust now than they were a few years ago but could improve. “We are in our own independent silos and those silos don’t cross over very well,” he said.

The terms shared spectrum and flexible use can have different meanings, said Richard Bernhardt, vice president-spectrum and industry at the Wireless ISP Association. Senate Commerce Chair Maria Cantwell, D-Wash., who has spectrum legislation before the Senate (see 2406120058), has one perspective on what sharing is, while DOD has a different view, he said. Similarly, the FCC, NTIA and industry have their own perspectives, he said.

While the conference's main focus was addressing spectrum clutter, sharing emerged as a major theme (see 2406110065).

Notebook

Clutter is good and bad for carriers, said Chris Wieczorek, T-Mobile director-spectrum policy. Where markets are adjacent, clutter helps reduce signals and interference, he said. It’s also bad for the same reasons, he noted. Wieczorek said the building where the conference is taking place is “an extremely cluttered environment.” T-Mobile’s signals are bouncing off walls, coming through windows and going through concrete, he said. “That’s a bad thing for consumers.” When the FCC auctioned AWS-1 licenses in 2006, “the whole concept of clutter was not even considered or analyzed,” he said. Eight years later, when the FCC auctioned AWS-3 spectrum, clutter still wasn’t part of the initial discussion. “We had to fight tooth and nail in the wireless industry to get clutter taken into account” and “into the analysis.” Today, the consensus is that clutter must be part of the analysis, he said. Carriers publish propagation maps showing where they think they have coverage, Wieczorek said. Sometimes the maps are “particularly high resolution … it depends on the carrier,” he said. Carriers are required under the Broadband Data Act of 2020 to submit coverage maps and "shapefiles" to the FCC. “I spend an inordinate amount of my time dealing with maps and clutter,” he said.

Working with NTIA, the FCC is looking at newer ways of modeling clutter and “how we can look at the measurements to try to refine the models to make sure that we have better models that we could possibly use in the future,” said Martin Doczkat, chief of the Technical Analysis Branch in the FCC Office of the Engineering and Technology. Spectrum consultant Tony Rennier, CEO of Foundry, suggested, “Nobody actually cares about clutter.” Instead, “We’re interested in whether ... we have too much interference or whether we can close the link of a radio that we’re designing,” he said. Clutter models are “a means to an end,” Rennier said, adding that all models are wrong, though some are more useful than others.