Experts Still Debating Viability of CBRS as Sharing Model

CTIA and Google officials clashed Tuesday on the future of spectrum sharing and the citizens broadband radio service band, speaking during a Broadband Breakfast webinar on spectrum sharing. Other speakers said CBRS has been a success.

The three-tier CBRS model has a part to play, in areas where Wi-Fi is inadequate and users want to manage their own networks, said Doug Brake, CTIA assistant vice president-policy communications. Carriers are among the largest users of CBRS, but it’s not their first choice, he said. CBRS “definitely plays a role, but it’s a narrow one,” he said.

“We’ve yet to see real evidence of success … apart from the strong demand for prime spectrum where it’s located,” Brake said. CBRS “isn’t ready for prime time,” he said. CTIA argued in a report last year that few CBRS access points are used nationwide and most companies have no plans to use the band (see 2211140062).

Google, which runs one of the spectrum access systems authorized in the CBRS band, is managing nearly 400,000 devices, said Andrew Clegg, Google spectrum engineering lead. The CBRS auction had 228 winning bidders, compared with the handful in most FCC auctions, he said. The FCC has also certified as of last week 744 models of CBRS base stations and nearly 2,000 end-user devices, he said.

Last year's CTIA report has been “widely debunked,” Clegg said. Drive tests looking at CBRS activity didn’t show much activity because of the low power levels used in CBRS, he said. The U.S. needs licensed and unlicensed spectrum, and the lightly licensed spectrum offered in the CBRS band, he said: “If you can’t clear the band, this is one of the best things you can do with it.”

“The way spectrum is made available directly impacts competition and innovation,” said Traci Biswese, NCTA associate general counsel. Spectrum policy should allow new entrants and avoid “putting spectrum into the hands of only a few,” she said. NCTA also supports the CBRS model, she said, noting the CBRS auction had 10 times more winning bidders than the 3.45 GHz auction a year later. “Even the NFL is a user of CBRS,” she said.

Target Bands

Biswese said the 3.1, 7-8, 13 and lower 37 GHz all should be targets for sharing with some licensing. “What’s more important is to ensure that we’re shaping spectrum policy in a way that promotes diversity and innovation,” she said. “We understand the importance of a diverse spectrum pipeline and a balanced spectrum policy,” she said.

Industry has proven it needs more licensed, full-power spectrum for 5G and 6G, Brake said. Independent forecasts predict as much as five times more mobile traffic in five years, “but we don’t have a real plan in place for the spectrum to get us there,” he said. Full-power spectrum is “the core workhorse of the mobile industry,” he said.

CTIA understands different approaches are needed in different bands, Brake said. “We’re not really talking about crowning one best model for all time,” he said. The low power levels in CBRS are a problem, he said: “This is prime 5G spectrum” and “we’re seeing only small, localized deployments, with very limited coverage.”

Clegg said he agrees with CTIA on some points. “If you can easily clear a band and quickly auction and use it exclusively, that’s not a bad way to go,” he said. The CBRS band “is a little challenging to operate in” and there are improvements that can be made, he said: “We’ve made concrete steps to improve CBRS reliability, improve spectrum availability and reduce the number of incumbent preemptions …. It is getting better.”

Virtually all low- and mid-band spectrum is already assigned and occupied, so sharing is unavoidable, said Michael Calabrese, director of the Wireless Future Program at New America. The carrier model has been exclusive-use licenses, but sharing makes more sense now for the wireless industry, he said. “Much of the need now is to add capacity in high-use areas and not for coverage,” he said. Advanced spectrum sharing technology also allows “far more intensive and diverse access to spectrum,” he said.

Geolocation database systems “unlocked enormous capacity” in both the CBRS band and soon in 6 GHz, Calabrese said. Factories, utilities, sporting arenas, schools and others increasingly want to set up their own probate networks and need spectrum like the CBRS band, he said.