What may be the most complicated spectrum swap yet is getting into gear – with due dates now inscribed in federal law – but the telecom exec tasked with helping to oversee this process professes no frequency fears."It's something that's been worked through a number of times in recent years," said Brian Regan, chair of the National Spectrum Coalition's new Partnering to Advance Trusted and Holistic Spectrum Solutions (PATHSS) Task Group.NSC launched this group on October 27 to coordinate with the Department of Defense in finding ways to share spectrum in the 3100-3450MHz band for commercial 5G service – the next chapter in a years-long effort to find and free up midband spectrum.The FCC just concluded a successful auction for the 3450-3550MHz band, netting $21.9 billion in winning bids. Those bidders, however, had to agree to DoD-mandated spectrum-sharing requirements that include geographic sharing requirements around such military installations as Camp Pendleton in California, Camp Lejeune in North Carolina and White Sands Missile Range in New Mexico.In this new, lower band, NSC's PATHSS group first needs to develop a complete inventory of just what DoD hardware today uses those frequencies."The critical thing here is that it's early enough in the process," Regan said. "DoD is going to be sharing a significant amount of information about those systems, how they operate, what the future need is, what the alternatives are."Everything is one the tableRegan cited radars in particular. A July 2020 report from the NTIA cites such DoD uses in the 3100-3550MHz band as "a high-power airborne radar" operated nationwide by the US Air Force and US Navy air traffic control operations on ships and in ports, and transportable, ground-based radars operated by the US Army and US Marine Corps.That report hesitated to call sharing the sub-3450MHz spectrum do-able at all, instead assessing that "ultimately some sharing of spectrum below 3450 MHz may be possible."Regan's judgment: Yes, it will."I think they're going to start from the premise of, all options for making this spectrum available on a commercial basis are on the table," he said. As in, the DoD and wireless operators could agree to share spectrum based on time, frequency, geography or power.Regan said the organization's background would help avoid compatibility glitches like the dispute over radio altimeters that has forced a holdup in AT&T and Verizon's rollout of C-Band spectrum. He also serves as NSC's treasurer and has a day job of VP for legal, policy and strategy at the fixed-wireless residential-broadband provider Starry."We've got a really unique membership," he said of the task group. "We've got 400+ members right now, which span from large wireless carriers to large defense contractors" – plus many smaller firms.And, Regan added, NSC has experience from an earlier round of spectrum clearance that required DoD cooperation – the AWS3 auction, in which the Pentagon freed up 1755-1780MHz spectrum."There was extensive amounts of federal uses in the band, there was a lengthy analysis that took place," he said. "The NSC was actually stood up as part of that."But although that spectrum auction concluded in 2015 with $44.899 billion in winning bids, some of the spectrum still hasn't been cleared. An August 2021 NTIA report noted that the Navy would need until October 2023 to hand over the last bits of its spectrum, while the Air Force would need until January of 2025.Avoiding conflictA clause in the just-passed Infrastructure Investment and Jobs Act places some deadlines on the 3100-3450MHz band. Section 90008 of the infrastructure bill provides $50 million to the DoD to help it free up airwaves in this band and calls for a completed inventory of available spectrum within 21 months. It also mandates a start of airwave auctions anytime after November 30, 2024, with government-used frequencies to be reassigned starting May 31, 2025."It really doesn't have to be a spectrum fight or whatever," Regan said. "It can be a much more collaborative effort to solve what is ultimately a really complicated collaboration problem" – with an outcome, he added, that "will ultimately accrue to the benefit of consumers and federal users alike."Because of the sensitive nature of some of the DoD operations involved, the path of PATHSS will involve some classified information – and Regan commented that the receding pandemic will make that easier."I think the classified meetings will all of them, by nature, take place face to face," he said. "Zoom is very good for some things, it's not very good for others."— Rob Pegoraro, special to Light Reading. Follow him @robpegoraro.