Shared Spectrum Model for 3.5 GHz Band Seen as Wave of Future

“Whether you like it or not, it's probably going to happen,” Marshall said of shared use of the 3.5 GHz band. “We don’t want to see something where we got a regulatory win but consumers don’t get anything out of it.” Marshall said any discussion 18 months ago on the topic would have focused on whether sharing the band was desirable, but now the focus is on making sharing work.

In April, the FCC approved a further NPRM seeking final comments on the use of the 3.5 GHz band as a kind of sharing test case and for small cells. Questions always have swirled around the use of the band, especially concerns that exclusion zones designed to protect naval operations in the spectrum are far too large (see 1404240041). Initial base cases for interference zones were far too conservative, Marshall said. “We think we’ve made people rethink the exclusion zone.”

The Department of Defense has come “a long way” in its thinking on dynamic spectrum sharing, Marshall said. “You’ve got to give DOD credit, they’ve really come far,” he said. “At least in this band they’ve really worked hard to understand our arguments.” If the rules required the kinds of exclusion zones discussed at last year’s FCC meeting, covering half the U.S. population, use of the band wouldn’t make economic sense, he said. Most likely the zones will take in only a “fraction of the population,” he said.

In another sign of progress, the Navy at one point said it could not accept listening devices that could compromise security, Marshall said. “It’s kind of humorous to see the Navy say, ‘Nobody can know where our carrier is,’” he said. “It comes under a bridge that thousands of cars drive over every hour. It’s in Google Maps. There’s a website in Japan that has every carrier location worldwide.”

Kurt Schaubach, chief technology officer at Federated Wireless, said over time there will no longer be the need for exclusion zones in the 3.5 GHz band. “It’s going to be a process of building confidence,” he said. “It’s going to be a staged process.” The band should be seen as a "proof of concept" rather than an experiment and should be a model for other bands, he said. "This is the beginning of the new way of thinking about how to regulate and allocate spectrum."

The 3.5 GHz band could provide an alternative to LTE-unlicensed, Marshall said. There’s a “real opportunity,” he said. “The guy who can figure out how to use the Wi-Fi model and deliver reliable LTE is the guy who wins the LTE business.” Schaubach said that sharing at 3.5 GHz could be helpful to improved wireless penetration inside buildings. Wi-Fi has been “tremendously successful” but can’t “scale” to the levels industry needs to handle unlicensed traffic, he said. The band is really targeted to small cell operations with power limits tailored to that use, he said.

The FCC has proposed a three-tiered access and sharing model composed of federal and nonfederal incumbents, priority access licensees, and general authorized access users, with use of the band managed by a spectrum access system (SAS). Speakers conceded the SAS would be the most complicated spectrum management system in history.

Spectrum's value is only increasing and spectrum will be commoditized, said Declan Ganley, CEO of Rivada Networks. Its technology allows companies to bid for use of a specific spectrum band in a specific location at a specific time, he said. “There’s no gatekeeper, other than the marketplace.” Ganley pointed to the technology to help FirstNet sell unutilized spectrum after the national network is launched. “It provides ruthless preemption for public safety,” he said. Ganley estimated that even mid-size states could see hundreds of millions of dollars in revenue by leasing out access to FirstNet spectrum.

Public safety will get access to the network when it needs it in just 30 milliseconds using the technology, Ganley said. “It’s imperceptible that anyone else is using the network.” Ganley suggested broadcasters could make a lot more money by leasing their spectrum and getting a monthly check rather than selling it in the TV incentive auction. DOD already is thinking about how its spectrum could be utilized by others, with the same “ruthless pre-emption” that FirstNet will have, he said.

Ganley also sees carriers taking a bigger interest in spectrum commoditization, though most are resisting so far. Some carriers have told Rivada that “we wish you would just go away,” he said. Subscribers don’t care what spectrum their smartphone is using, just that it works, he said. “It took carriers 25 years to understand that they weren’t in the tower business.” Mexico is leading the way with a proposal by regulators to run a bandwidth market, he said. Australia is also investigating a spectrum exchange. A spectrum exchange is a more efficient way to reallocate spectrum than one-off FCC auctions and bidding wars, he said.

U.S. carriers have a simple strategy on spectrum, “they want it all,” said Darrin Mylet of 6 Harmonics, which targets TV white spaces. Carriers “have gotten greedy,” he said. Mylet said some FCC commissioners called at CES for a slowdown in the move to an incentive auction so carriers can reboot after the AWS-3 auction. “Who does the FCC work for?” he asked. Mylet said that worldwide, no more than 10,000 white spaces devices have been sold.