FCC and NTIA Take Steps to Expand Reach of CBRS Band

The FCC Wednesday notified certified spectrum access system administrators in the citizens broadband service band that they are now permitted to implement changes to the existing aggregate interference model used to protect federal operations in the band. Among the changes, SAS administrators may now assume an 80% time division duplex activity factor and 20% network loading factor for each CBRS device in the aggregate interference calculation, said a notice from the Wireless Bureau and Office of Engineering and Technology. Administrators may use median irregular terrain model terrain dependent propagation loss “using reliability and confidence factors of 0.5 -- to calculate the aggregate received power levels” within a protection area. The FCC urged administrators to submit a demonstration of their ability to implement the new testing parameters in docket 15-319. NTIA approved the changes in a letter to the FCC posted Wednesday. “The changes outlined … will expand Internet access to more people across the country,” said NTIA Administrator Alan Davidson: “They could not have been implemented without the collaboration of the Navy and our ongoing coordination with the FCC.” The change will expand use of the band to tens of millions of Americans, said FCC Chairwoman Jessica Rosenworcel. “The CBRS dynamic spectrum sharing framework is already fertile ground for wireless innovation, and through collaboration with [DOD], NTIA, and stakeholders, we are expanding opportunities for reliable spectrum access while also ensuring that federal incumbents remain protected,” she said. The changes authorize service to approximately 72 million more POPs and expand the total unencumbered CBRS area to roughly 240 million POPs nationwide, the agencies said. CBRS is a prime example of how industry and government can coordinate on spectrum, Ira Keltz, deputy chief of the FCC’s Office of Engineering and Technology said Wednesday at the International Symposium on Advanced Radio Technologies (ISART) conference in Denver. When CBRS started, the initial exclusion zones were “huge” and would have excluded 75% of POPs, he said. NTIA, working with engineers, was able to reduce the size of the zones so that CBRS made more sense, industry was willing to invest, and the Navy felt comfortable that its radars would be protected, Keltz said. “It just really comes down to people being open-minded,” he said. Derek Khlopin, NTIA deputy associate administrator, noted the work to make CBRS work better. “These improvements we’ve made have been phenomenal,” he said, also at the ISART conference. He credited the Navy for its willingness to work with the NTIA and the FCC. “With little ‘greenfield’ spectrum available yet ever-increasing demand for spectrum-driven utilizations, sharing allows more efficient use of limited spectrum resources,” emailed Richard Bernhardt, vice president-spectrum and industry at the Wireless ISP Association: The development “will provide more predictability and allow for approximately 72 million additional people to be covered by CBRS without having to move or change power due to Federal operations.”