CableLabs wants to test unlicensed LTE in Clearwire spectrum

CableLabs wants to use Clearwire's 2.5 GHz spectrum to test how LTE-Unlicensed (LTE-U) and Licensed Assisted Access (LAA) co-exist with Wi-Fi networks.

The organization is asking the FCC for a 24-month experimental license to conduct the tests. It's got the blessing of Sprint (NYSE: S), which acquired 100 percent ownership of Clearwire in 2013.

Rob Alderfer, principal strategist analyst at CableLabs, FCC, told FierceWirelessTech that CableLabs is testing to see how to make LTE/LAA and Wi-Fi play nice together. "We are coordinating with Sprint," he said.

"We've done some tests in our lab" in a chamber that basically consists of a metal box that is shielded from the outside world so no RF gets out. Testing in a chamber like that does not require an experimental license, he said. "We'd like to take our research to the next step, which is to move out of the lab into a real world environment."

All of this experimental testing will be conducted indoors. CableLabs is renting a house in Brighton, Colo., for the purpose of doing wireless testing. That way, it can set up multiple devices and mesh networks and look at interference that reflects usage within a residence.

Because LTE-U/LAA has been on an industry fast track, with the 3GPP looking to standardize the LAA version, "we'd like to ramp up our research as quickly as we can," he said.

CableLabs hopes the FCC will approve the application, and having done advanced coordination with licensee Sprint should help that effort. Alderfer said he's not sure how long it will take the FCC's engineers to consider the application, although he expects it will be approved.

The FCC released a public notice this week asking wireless industry stakeholders to share information on the development of LTE-U and LAA. The commission said it has heard from a number of organizations that have weighed in on the development of LTE-U and LAA in the context of the 3.5 GHz and 5 GHz proceedings. Some expressed concerns that LTE-U and LAA operations may have a detrimental impact on existing and future use of unlicensed or shared spectrum; others say it can lead to more efficient use of spectrum.

The FCC staff says the impact of LTE-U and LAA on unlicensed operations and technologies such as Wi-Fi would be quite different in the 3.5 GHz and 5 GHz bands; the 3.5 GHz band is generally newly available spectrum while the 5 GHz bands are already heavily used by Wi-Fi and other unlicensed devices.

CableLabs representatives have said previously, and Alderfer reiterated, that they believe technical mechanisms can be designed so that LTE and Wi-Fi can co-exist together in unlicensed spectrum.

"We think there are technical mechanisms that can be designed to help LTE unlicensed play nicely with Wi-Fi, and our research is going to be designed to prove that out," he said, adding that it's one thing to have it work in a research environment and another in a network deployment, "so that's really what's going to be important here."  

For more:
- see this letter
- see this application and this application

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