As carriers and the FCC continue to warn of an impending broadband wireless spectrum shortage, we’re going to be hearing a lot more about spectrum sharing moving forward.
Blair Levin, the former FCC official and current executive director of the Gig U initiative, first alerted us that regulators were taking a keen interest in spectrum sharing back in March. “It’s too difficult to dislodge incumbents,” Levin told us. Instead, he said he expected regulators to pursue a combination of spectrum auctions and spectrum sharing.
Just a few weeks later the National Telecommunications and Information Administration issued recommendations about where the government could free up more spectrum for broadband – and among other things, the agency recommended looking into whether certain spectrum bands currently allocated to the government could be shared with commercial users.
When telecom industry stakeholders heard that, I would venture that most of them envisioned some sort of technology-based approach, such as the one that Spectrum Bridge and others are using to enable vacant television spectrum known as “TV white spaces” to be used for broadband through sophisticated database management.
But apparently technology-based sharing isn’t the only type of sharing under consideration. According to a report this week from the Telecommunications Law Research Center, the government also is considering spectrum sharing on a geographic basis or on a temporal basis. The report cites unnamed “people with knowledge of the matter” who said that in some instances, government spectrum may be in use for only several minutes of each day.
If that’s true, temporal spectrum sharing might seem to have strong appeal. But unless the times of day that the government needs to use spectrum are during times when cellular traffic is lowest, that idea may have little appeal for network operators.
The Telecommunications Law Research Center report did not speculate about the geographic areas where the government would need to continue to use its spectrum. But if the government’s usage pattern is anything like that of commercial users, it is likely concentrated in metro areas, which means that idea also may have little appeal to larger carriers – although it could appeal to more rural carriers.
For now, though, I would expect network operators generally to be more supportive of technology-based spectrum sharing. The concern is how quickly the technology could be made ready. Several industry sources told the Telecommunications Law Research Center that they did not believe spectrum sharing technologies would be ready for deployment any time soon.
A key idea under consideration is to use cognitive radios that would look for unused spectrum bands. But questions have arisen about whether spectrum sharing technologies based on a cognitive radio approach would be compatible with LTE, the wireless technology that has emerged as the winner in the high-speed mobile broadband arena in the U.S.
Wireless consultant Peter Rysavy told the Telecommunications Law Research Center that LTE assumes the availability of a clear licensed band and would not be able to work with cognitive radios without a massive re-design.
At least one mobile operator seems open to the idea of spectrum sharing, however. T-Mobile has received authorization from the FCC to test the spectrum sharing concept in certain spectrum bands, the Telecommunications Law Research Center reports.
It makes sense that T-Mobile would be more open to the idea of spectrum sharing than larger wireless carriers AT&T and Verizon Wireless, who have dominated recent spectrum auctions. If spectrum sharing were to work, T-Mobile and other smaller operators might see spectrum sharing – if practical – as a way of helping to level the playing field.