'CBRS 2.0' Seen as Laying Path for Further Changes to 3.5 GHz Band

Expanding the reach of the citizens broadband radio service band via reworking the aggregate interference model (see 2406120027) opens the door to further significant CBRS operational changes, wireless and spectrum experts said Tuesday. They spoke during a CBRS seminar that the New America's Open Technology Institute sponsored. Preston Marshall, chairman of the OnGo Alliance, which promotes spectrum sharing, said that while the "CBRS 2.0" operational changes announced this month were uniformly beneficial to users, future "CBRS 3.0" discussions could start edging into areas, such as power levels, where there would be winners and losers. He said industry needs to come to a coherent, cohesive position to present to regulators rather than the government having to "arbitrate a food fight."

The FCC, NTIA and DOD have a slew of CBRS operational improvements they could consider -- such as modified out-of-band emission limits -- that would improve access for industry while still protecting incumbent federal users, such as Navy radar installations, said Jennifer McCarthy, Federated Wireless vice president-legal advocacy. Current OOBE limits in the 3.5 GHz band "are tight," while adjacent bands enjoy more lax OOBE limits, she said. Allowing higher-power CBRS operations would improve rural coverage, but McCarthy acknowledged it's potentially "a third-rail topic." Manish Jindal, Charter Communications group vice president-wireless research and development, pointed to both the FCC's Technology Advisory Council and NTIA's Commerce Spectrum Management Advisory Committee having raised further propagation model improvements as a possible direction for future CBRS rules modifications.

The aggregate interference model changes for the 3.5 GHz band will mean an additional 72 million more Americans get access, speakers said. Andy Clegg, Google spectrum engineering lead, said smaller dynamic protection area (DPA) neighborhoods means DOD operations will affect fewer devices, and devices still in those neighborhoods will see less-severe impacts. Following the model changes, "If you can't smell saltwater," DOD operations probably won't impact you, he quipped. Clegg said the CBRS changes should be implemented by the end of summer at the latest.

The biggest impact of smaller zones where CBRS devices are susceptible to preemption from incumbent federal activities comes in indoor deployments, the OnGo Alliance said Tuesday. Smaller zones will mean 97% of the U.S. landmass will be outside disruption areas, compared with 78% now, it added. The CBRS 2.0 changes will also mean devices outside incumbent operations areas can operate for up to 24 hours without reauthorizing with the Spectrum Access System.

Pointing to the CBRS NPRM circulated last week seeking further changes to the band (see 2406130055), Jonathan Campbell, wireless aide to FCC Chairwoman Jessica Rosenworcel, said the aim is "to keep this good thing growing." The NPRM proposes adoption of DPA-based protection methodology for incumbent federal facilities, he said. The NPRM also asks about supporting general authorized access coexistence in the band and routes for accommodating private network and low-power indoor facility deployments, he said.

Speakers were repeatedly bullish on the CBRS spectrum-sharing regime. NTIA Principal Deputy Assistant Secretary Sarah Morris said not a single example of harmful interference to federal operations was reported.

Charter's CBRS spectrum holdings are a huge part of its mobile service offering, Jindal said. By 2025, Charter expects it will access nearly 50 million Wi-Fi and CBRS access points, Jindal added. Charter has technology that allows seamless transfer between its CBRS network and its Verizon-provided mobile virtual network, Jindal said.