LTE, Wi-Fi delegates collaborate, not clash, during coexistence workshop in Beijing

Despite what appeared to be a lot of defensive posturing before the meeting, there were no fists flying when delegates from the Wi-Fi and LTE communities met over the weekend for a 3GPP coexistence workshop in Beijing to discuss Licensed Assisted Access (LAA) technology.

On the contrary, those who attended the meeting, both from 3GPP and Wi-Fi perspectives, told FierceWirelessTech that they were pleased with the degree of collaboration that occurred. LAA and a precursor technology called LTE-U have been points of contention between the two camps, with Verizon (NYSE: VZ) and T-Mobile US (NYSE:TMUS) last week blasting the Wi-Fi Alliance for a proposal that the alliance become a "gatekeeper" for technology in unlicensed spectrum.

During the workshop in Beijing on Saturday, both sides appeared to be making strides on the collaboration front, at least when it comes to the technical details. But the topic of the workshop was the evolving standard LAA, not LTE-U, which has generated more concern in the Wi-Fi community. LTE-U is a separate method of deploying LTE in unlicensed spectrum and one that vendors and U.S. operators are hopeful they can roll out in 2016, but one that also poses more concerns for the unlicensed stakeholders, which include the Wi-Fi Alliance and cable companies.

The 3GPP RAN workshop on LAA was hosted by Chinese vendor Huawei Technologies and came after a week of technical committee meetings. According to a draft of the minutes from the meeting, more than 200 people attended the weekend workshop.

The meeting was chaired by 3GPP TSG RAN Chairman Dino Flore, who is senior director of technical standards at Qualcomm (NASDAQ:QCOM) and a former research engineer at ArrayComm, the smart antenna company founded by cellular pioneer Marty Cooper. Other companies with representatives at the meeting included Ericsson (NASDAQ: ERIC), Cisco, Alcatel-Lucent (NYSE: ALU), Panasonic, Samsung, Intel, Cablevision (NYSE: CVC), CableLabs, Ruckus Wireless, General Motors and others.

Flore told FierceWirelessTech via email that the workshop was quite successful and will help strengthen the collaboration between 3GPP, IEEE and the Wi-Fi Alliance, "thanks also to a better mutual understanding of each other's processes that was achieved at the meeting. So we do expect the collaboration between our organizations to continue and even improve as the LAA standard gets further developed (as it was established at the meeting, so far 'things are going in the right direction'), so that in the end we can achieve the ultimate goal of fair sharing of unlicensed spectrum between LAA and Wi-Fi."

Paul Nikolich, IEEE 802 LAN/MAN Standards chairman, told FierceWirelessTech that he wasn't sure what to expect going into the meeting but he was pleased that progress is being made among the stakeholders. "We're talking about industries that have very different cultures," from a technical specification development point of view, he said, speaking from his own personal perspective and not on behalf of the organization.

The way the 3GPP achieves consensus is by companies whereas the 802 community does it based on individuals. Broadly speaking, however, the principles are the same, with both trying to create the highest quality specs, he added. He characterized the tone of the meeting as very respectful, and from an 802 point of view, "we explained what we would like to see in terms of the interaction between the two groups," he said. "It was a good meeting."

Lorenzo Casaccia, senior director of technical standards at Qualcomm Europe, also said he was pleased with the collaboration at the LAA workshop. As for prior contentious issues, "there could be multiple factors for past misunderstandings," he said. "One reason was due to a misunderstanding on how spec development operates in 3GPP and IEEE: It is not done in the same way in the two organizations. This was discussed in great detail at the workshop, and we're very pleased that there was a recognition among attendees that the collaboration over LAA is now moving in the right direction."

The IEEE 802 suggested that 3GPP consider using an external review processes similar to those used by the IEEE Standards Association. While the LAA standards development is moving at a very fast pace, it was reassuring for the 802 community to know that there are certain conditions under which revisions can occur.

IEEE 802 also said that 3GPP should consider "802.11-like" access for LAA, using a collaborative development process, and it's moving in that direction, Nikolich said.

Since the LAA process started more than a year ago, "I feel like we have a much, much better understanding," he said. Will there continue to be more collaboration between 802 and 3GPP? "Absolutely, it needs to happen," Nikolich said, adding that the two industries are overlapping more and more and both organizations understand the need for more collaboration.

The Wi-Fi Alliance and cable industry brought their concerns on LAA to the Beijing meeting as well, saying it's the Wi-Fi Alliance's understanding that 3GPP will require listen before talk (LBT) in all regulatory domains and it is generally pleased with the 3GPP's direction toward a single Category 4 LBT algorithm. However, significant analysis and simulation work is still required before finalization to ensure coexistence with Wi-Fi.

In a separate but related matter, the Wi-Fi Alliance remains concerned about the evolution of LTE-U. Greg Ennis, vice president of technology at the Wi-Fi Alliance, said the LAA standard evolution, which has resulted from the 3GPP process, is a good example of the value of an inclusive standard development method. "By considering input from a variety of stakeholders, 3GPP appears headed in a direction that will facilitate LAA's fair spectrum sharing," he told FierceWirelessTech. "In particular, 3GPP has stated that the LAA standard will specify one 'listen before talk' algorithm to be used in all geographies. While there are still significant technical details to work out for LAA, this universal 'listen before talk' algorithm signals a commitment to fair sharing. Other planned LTE technologies for unlicensed use lack such necessary etiquette protocols."

"LTE-U was developed in private, in contrast to LAA and in contrast to recognized standard development methods," Ennis added. "The result is that the LTE-U specification allows wide variances in implementation and configuration choices, and therefore the extent to which LTE-U shares spectrum with other technologies can vary widely from one vendor to the next. Since such considerations were lacking in the development of LTE-U, they must still be considered before LTE-U equipment is deployed. Further work is necessary to ensure the range of expected LTE-U implementations can coexist fairly with Wi-Fi."

Mingxi Fan, vice president of engineering at Qualcomm Technologies, was among those who made presentations during Qualcomm's media event last week where it sought to set the record straight about LTE-U. Fan said Qualcomm has held deep technical bilateral discussions with many Wi-Fi vendors and service providers. "We have even invited Wi-Fi groups to come into our lab to do coexistence testing," he said. "As a result of our efforts, in our direct discussions, the Wi-Fi community has shifted from a position of outright hostility to LTE-U to concerns over how the coexistence mechanisms can be enforced in LTE-U products."

Fan added: "From LTE-U Forum perspective, our view is that the fact that the coexistence specification and respective tests are public shows the commitment from Verizon and LTE-U Forum vendors to adhere to and enforce the coexistence mechanisms. Also, as we address these concerns, it's important to bear in mind that there is no baseline Wi-Fi to Wi-Fi coexistence mechanism, much less any enforcement of a Wi-Fi baseline. As a result, our testing has shown that, today, Wi-Fi products have wide variation in product behaviors, including unfair sharing with each other. In any event, the LTE-U Forum coexistence tests are designed in a way such that LTE-U shares the spectrum fairly and never uses it for more than its proportionate share of the time."

Ennis noted that the Wi-Fi Alliance is developing a coexistence test plan aimed at assessing fair sharing, and the Wi-Fi Alliance plans to host a series of workshops on the topic starting in early November.  

For more:
- see this 3GPP site

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