FCC seeking comment on LTE-U, LAA tech

While industry experts debate the merits of LTE-Unlicensed (LTE-U) and Licensed Assisted Access (LAA), the FCC formally kicked off a comment period seeking input on a range of topics related to the technologies.

At the FCC's open meeting last month, Chairman Tom Wheeler said the commission was going to open up a separate proceeding that looks specifically at LTE-U/LAA. Wheeler acknowledged that many commenters in the agency's proceeding on 3.5 GHz were concerned about the technology, which is being examined in the standards-setting process.

Wi-Fi providers are concerned cellular operators will deploy the technology in unlicensed bands and negatively affect Wi-Fi users. AT&T (NYSE: T), for one, has said it won't deploy LAA until it is sure it won't interfere with Wi-Fi. T-Mobile US (NYSE:TMUS) and Verizon Wireless (NYSE: VZ), on the other hand, are more aggressively pursuing LTE-U and LAA.

Clearly, Commissioner Michael O'Rielly isn't fully on board with the inquiry. "Today's public notice walks a fine line between reasonable oversight and inappropriate interference with the standards setting process," he said in a statement. "The decision to jump into this space rather casually causes me great concern. In particular, any step that could insert the Commission into the standards work for LTE-U comes with great risk.

"I will be vigilant in ensuring that the Commission's involvement does not result in taking sides with various stakeholders, hindering technological innovation, or having any say about what technologies should or should not be deployed," he added.

The FCC said in its public notice that a number of organizations have approached the commission about the development of LTE-U and LAA in the context of the 3.5 GHz and 5 GHz proceedings. Some expressed concern that "LTE-U and LAA operations may have a detrimental impact on existing and future use of unlicensed or shared spectrum," the notice said.

Others have asserted that LTE-U and LAA are more efficient than other currently available unlicensed technologies, that LTE-U and LAA include features to share the spectrum fairly with no detrimental impact on existing users of the spectrum and that consumers ultimately will benefit from increase access to spectrum, the commission added.

The notice points out that while the 3GPP is working on the LTE-U and LAA standards and the IEEE Working Group 802.11 develops standards for wireless local area networks such as Wi-Fi, those organizations have a limited historical working relationship given their different backgrounds and scopes. "We are aware that some companies have formed the LTE-U Forum, which is considering deployment of LTE-U/LAA using a 'pre-standard' version of LTE-U/LAA," the FCC's notice said.

The FCC says it remains committed to its historical policy of remaining technology neutral, but it is opening the docket to provide an opportunity for interested parties to enable a "fully participatory and transparent discussion about LTE-U and LAA technologies" and how they will co-exist with other technologies like Wi-Fi.

The commission sets forth a list of more than 10 questions, asking everything from the current status of coordination between 3GPP and IEEE 802.11 on LTE-U and LAA to what tests or analyses have been performed to understand the impact of LTE-U and LAA on existing commercial wireless and unlicensed ecosystems.

Comments are due June 11, with reply comments due June 26. 

At the Wi-Fi Innovation Summit about two weeks ago, panelists on both sides of the issue debated the merits of the technology, with LTE-U, generally speaking, being seen as the one that is most troubling for the Wi-Fi community.

Earlier, during a Q&A session at the Brooklyn 5G Summit in mid-April, AT&T's Tom Keathley was asked about how AT&T views the sharing of unlicensed spectrum. "The real question now is can you do that with the duty cycle methodology, listen, and then transmit, but not listen before talk. That's the LTE-U methodology. Or do you have to wait for Licensed Assisted Access, where you will get a true listen-before-talk methodology implemented as that LTE standard changes," said Keathley, senior vice president of network and product planning at AT&T.

"Right now, we don't know the answer to that," he said at the time. "We're evaluating it, and we'll make a determination around a couple of items. If you can share it in a fair use manner, then we'll have to ask ourselves whether it's worth deploying that true, pre-standards version in advance of licensed assisted, and frankly, we don't know that."

In other unlicensed LTE news, a T-Mobile US executive said recently that the carrier's deployment of LTE in the unlicensed 5 GHz bands, scheduled for next year, likely would include "listen before talk" (LBT) technology, according to Light Reading. LBT is a relatively standard part of Wi-Fi transmissions, and the Wi-Fi community has urged its inclusion in any deployment of LTE in unlicensed spectrum.

For more:
- see this public notice
- see Commissioner O'Rielly's statement
- see this Computerworld article
- see this Light Reading article

Related Articles:
Wi-Fi, LTE worlds bump into each other in WIS panel debate
FCC votes to adopt new 3.5 GHz spectrum sharing plan for 'Innovation Band'
LAA/LTE-U makes appearance at Brooklyn 5G summit

Article updated May 7 to include new information on T-Mobile's deployment plans.