FCC Making Progress on 3.5 GHz, 5.9 GHz Bands, But Tough Problems Remain, Chief Engineer Says

“So many of the things that we have been doing involve sharing of spectrum, perhaps more than anytime in the past,” Knapp said. Decisions are much more complex, he said. In early days, the FCC identified a band, “had a debate over whether it was lightly used or not” and then it reallocated it, he said. That approach “worked fine for the time, but there are a lot more operations in the spectrum today and we’re trying to pack more and more together,” Knapp said.

Collaboration is also critical, Knapp said. The FCC couldn’t have tackled the AWS-3 band and many other areas “without the collaboration between NTIA and federal agencies and the industry and, I think, all of the people in this room,” he said. The launch of the massively complex TV incentive auction was a “monumental accomplishment,” he said.

The Wireless Innovation Forum’s work on the 3.5 GHz band (see 1605110015) moved use of the band closer to reality, Knapp said. “Getting everybody together in the room to solve all of the details of how this is going to work, I think, was probably one of the best things that we as an agency could have done.”

The FCC was pleased companies applied to be both spectrum access system (SAS) administrators and environmental sensing capability (ESC) operators in the 3.5 GHz band, Knapp said. Seeking companies to participate is like planning a party, he said. “You wonder when you send the invites out to the party is anybody going to show up,” he said. “We’re in the midst of the approval process,” he said. “It’s going to take some time working through all of that.”

Knapp also highlighted the FCC spectrum frontiers order (see 1607140052), which he said approved almost 11 GHz of spectrum for 5G and mobile use. A further 18 GHz is teed up in a Further NPRM, he said. Work on the 5G spectrum will be “the greatest boon” for communications lawyers and spectrum engineers based on the amount of work that will have to be done, he said. “We want to keep up that momentum as we move forward.”

The 5.9 GHz band is at the high end of other spectrum set aside for unlicensed use, Knapp said. Interference testing is getting underway, he said. Friday, the FCC received prototype devices for testing from Broadcom, CAV Technologies and KEA Technologies, with devices still to come from Qualcomm and Cisco (see 1607290059), he said.

“We’ve done a lot,” Knapp said. “We’ve still got a lot to do. These problems are hard.”

FCC Watching Two-Way Sharing

Knapp was asked if he sees any impediments to federal agencies getting easier access to commercial bands as part of bidirectional sharing, the topic of a report CSMAC approved in June (see 1606080050). FCC Chairman Tom Wheeler raised the issue last year (see 1508030071). “Largely in the past, that didn’t happen,” Knapp said of two-way sharing.

Some federal agencies are now saying, “I’m willing to share, but how about the other direction?” Knapp said. “I think there’s a sense that they are able to share nonfederal in places that they [agencies] would not have an impact on the nonfederal users,” he said. “We have more work to do on that point going forward.” A first step would be establishing ground rules, he said. “Sometimes, there’s an issue of consistency with the allocation table and how do we deal with that and what are the conditions that apply for this sharing.”

“We continue to live in exciting times,” said NTIA Associate Administrator Paige Atkins. NTIA is still deciding what the next phase of CSMAC will examine, she said.

Atkins said the recently announced Advanced Wireless Research Initiative (AWRI) (see 1607150035), a $400 million program spearheaded by the National Science Foundation, has a big role. “We really need to put in place the building blocks of research and technology development that will help make frontiers, as well as 5G, a reality,” she said.

Finding Engineers Difficult

Keith Gremban, director of the Institute for Telecommunication Sciences, who also spoke to the CSMAC, said one issue in spectrum research is that there are too few qualified people. The institute has been posting a lot of jobs this year “and it has not been easy finding good radio engineers,” Gremban said. Finding software engineers with the right math and physics background is “even harder,” he said. “We’re having to look very hard to find the right people.”

The CSMAC received a final report on the challenges of a 5G world, as expected (see 1607280040). CSMAC also discussed final reports from its various other subcommittees as the current term of the group ends.

A report by CSMAC's Measurement and Sensing in 5 GHz Subcommittee found both strengths and weaknesses on sensing, the approach the FCC is taking in the 3.5 GHz band. The systems require “minimal legacy system operator participation” and indirectly measure propagation losses enabling “the largest amount of potential spectrum sharing,” the report said. Among the weaknesses, systems need to be designed for specific bands, the report said. “Some measurement architectures require deployed monitors and related infrastructure, which is expensive.” There are also security issues and “measurements made co-existing with entrant system have the potential to block detection of harmful interference problems,” the report said.

The subcommittee recommended the use of different measurement techniques in different bands to determine the viability of spectrum sharing for the U-NII-2B (5350-5470 MHz) and U-NII-4 (5850-5925 MHz) bands. “The lower band can employ high gain antennas over long periods of time with clear line of sight to airport and space assets in order to determine spectral use,” the report said. “The upper band will be more challenging due to the distributed transmission characteristics and will require either distributed spatial measurements or employing some form of signal augmentation techniques.”

One priority should be an “accurate” spectrum dashboard for 5 GHz and other bands, the subcommittee said. “Without understanding what is in the band today at a detailed level and planned for tomorrow, as well as the technical characteristics of those systems, it is extremely difficult to assess or create sharing opportunities.”

CSMAC’s Agency to Industry Collaboration Subcommittee recommended NTIA investigate other government/non-government structures for effective collaboration. “The National Spectrum Consortium (NSC) and the National Advanced Spectrum and Communications Test Network (NASCTN) should both be studied by the NTIA as potential models for technical data sharing between government/non-government entities,” the report said. “The subcommittee has determined that both of these entities have been able to allow sharing of protected information.” NTIA should also look at how other Federal Advisory Committee Act committees operate, the report said.