LTE-U coexistence moves along but not fast enough for some stakeholders

While some LTE-U stakeholders are frustrated with how long it's taking, the Wi-Fi Alliance says it's on track to meet its goal of releasing this summer a final test plan for ensuring coexistence between LTE-U and Wi-Fi in unlicensed spectrum.

The Wi-Fi Alliance hosted a Coexistence Test Workshop in San Jose on Tuesday, where attendees representing a cross-section of Wi-Fi, cable and wireless industries presented their contributions in order to move the whole process forward.

"There are still disagreements – don't get me wrong -- but attendees are having reasonable discussions and debate to come to consensus" around their areas of disagreement, Kevin Robinson, VP of marketing at the Wi-Fi Alliance, told FierceWirelessTech.

Stakeholders are making good-faith efforts to make positive contributions to move the effort forward, and that commitment was certainly maintained through the workshop, he said. By way of example in how contributions are being made, the Wi-Fi Alliance needs access to LTE-U equipment to conduct the validation process, so it's reliant on others for that. Toward that end, one LTE-U vendor, Qualcomm (NASDAQ:QCOM), made a commitment to provide equipment to support the process. Robinson characterized that as a positive development, and the Wi-Fi Alliance is looking for similar commitment from others in order to move work items forward.

Qualcomm, however, still isn't happy with the pace of the process. "Qualcomm believes that the Wi-Fi Alliance's timeline for finalizing the test plan needs to be greatly accelerated," Dean Brenner, SVP, Government Affairs at Qualcomm, said in a statement provided to FierceWirelessTech. "For many months, we have bent over backwards to collaborate with the Wi-Fi Alliance and our colleagues in the wireless industry to finalize a joint test plan and to prove — once and for all — that LTE-U will not have any detrimental effect on Wi-Fi — despite the mountain of evidence already proving this."

He also said that for several months, Qualcomm has offered to provide prototype LTE-U equipment to the Wi-Fi Alliance so the test plan can be finalized, but the Wi-Fi Alliance has not been ready to accept its offer. That apparently changed this week, as the Wi-Fi Alliance confirmed to FierceWirelessTech that it has accepted the offer. 

Brenner added: "We also provided feedback on the version of the test plan released on April 1 and engaged in deep technical collaboration to answer questions, provide technical feedback, and ease concerns. While it is positive that a deadline of late June was set to establish the mandatory energy detection levels in the final test plan, prior drafts of the test plan from months ago already included such levels. The time already taken to complete the test plan has been extended for much too long. This process needs to be completed soon. We will continue working to achieve this end result so this innovative technology can be used to deliver improved mobile service to U.S. consumers."

Qualcomm's desire to move faster is understandable given it's been an early supporter of LTE-U and the sooner equipment is out there, the sooner it and its operator partners can reap the benefits. Robinson said the Wi-Fi industry is certainly mindful of the commercial interests of LTE-U vendors and there's always a balancing act between their desire to get equipment out into the market and the Wi-Fi industry's goal of making sure there's no adverse impact on Wi-Fi.

T-Mobile US (NYSE:TMUS) CTO Neville Ray also expressed a degree of frustration this week when he talked with analysts during the company's quarterly conference call. "We're frustrated," he said. "We're not seeing the progress that we would like to see. We still have an ambition to push solutions into the marketplace inside 2016 but based on, from where we are from a regulatory perspective at this point in time... the light is dimming there a little. But that said, we are making good progress. We have an STA under review with the FCC which would allow us to advance testing."

Ray also said the company has a commercial kind of small cell product ready to roll that's LTE-U capable. The handsets "being the long pole in the tent, we're still pushing with our OEMs for 2016 capability," he said. "That piece may slide into early 2017, but that's kind of the timeframe for us at this point in time. It's a 4Q kind of 1Q 2017 story and we're going to keep pushing very, very hard."

One of the biggest topics of debate has been around what level one would expect an LTE-U device to become aware of nearby Wi-Fi and potentially defer transmission, according to Robinson. Where that threshold is set has important implications for coexistence with Wi-Fi. The guiding principle over all of it is to make sure the introduction of LTE-U has no greater impact on Wi-Fi than if a second Wi-Fi network were to be introduced.

The alliance also is in the process of identifying a third-party test house that can serve as an independent test laboratory. Robinson also noted that the Wi-Fi Alliance is moving faster on the LTE-U test regime process, which started around November, than it has with any of its own certification programs. It's incumbent on anyone interested in moving the final LTE-U/Wi-Fi test process along to be involved and make contributions, he said.

Related articles:
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Wi-Fi Alliance: Work on LTE-U testing regime ongoing, but it's unclear when it will be finished
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