Qualcomm has attacked the latest draft of an industry LTE-U/Wi-Fi coexistence test plan as “fundamentally biased against LTE-U” and called on the Federal Communications Commission to ignore it.
Wi-Fi Alliance held its most recent industry workshop on LTE-U coexistence testing this week, continuing to work toward its goal of delivering a test plan that will ensure fair play between Wi-Fi and LTE-U at five gigahertz. Previous workshops seemed to be largely cooperative, but this time Qualcomm emerged and blasted the latest version of the test plan as “unacceptable,” and said that it makes unreasonable requirements for LTE-U to protect Wi-Fi and that the test plan itself “lacks technical merit.”
Wi-Fi Alliance’s work was established as a cooperative effort between the Wi-Fi community and LTE-U supporters to work out coexistence concerns. LTE-U is the approach that Qualcomm, Verizon Wireless and others developed to leverage unlicensed spectrum alongside licensed LTE. Although it is based in LTE releases, it includes proprietary approaches to the coexistence mechanism between LTE and Wi-Fi. License-Assisted Access, or LAA, requires a listen-before-talk approach to Wi-Fi coexistence with LTE and was established through the 3GPP standardization process. LAA is required in Europe, Japan and other regions, while the U.S. and some other markets have not required an LBT approach and LTE-U would be allowed. A more rapid time to market has been seen as one of LTE-U’s biggest advantages, and the amount of time spent on coexistence testing details has made some proponents fretful – but Wi-Fi stakeholders are still nervous that fundamental operational differences between Wi-Fi and LTE mean that Wi-Fi will be significantly degraded by neighboring LTE-U installations in real-world situations.
Wi-Fi Alliance’s Kevin Robinson, VP of marketing, issued a statement on this week’s workshop that said in part: “Reaching cross-industry agreement and ensuring the best outcome for Wi-Fi users is an unprecedented and difficult endeavor, and all sides have had to compromise to reach this point. Discussion to conclude a number of outstanding items and finalize the test plan will continue through the Beta test plan phase over the next few weeks.”
Robinson said that the test plan is still on track to be finalized by Sept. 21. Two test labs, Cetecom and AT4, expect to be able to offer coexistence testing as soon as the plan is complete. Presentations from this week’s workshop are available for download from Wi-Fi Alliance.
The statement from Qualcomm’s Dean Brenner read in full:
“The latest version of the test plan released by the Wi-Fi Alliance lacks technical merit, is fundamentally biased against LTE-U and rejects virtually all the input that Qualcomm provided for the last year, even on points that were not controversial. We saw that a Wi-Fi group yesterday called this new version of the plan a compromise. In truth, we submitted a compromise proposal which the Wi-Fi Alliance rejected in its entirety and instead issued this plan, which has the clear purpose of trying to keep the benefits of LTE-U away from consumers and off the unlicensed spectrum, which is supposed to be for all of us.
“The latest version of the plan would require LTE-U to protect Wi-Fi 100-times more than Wi-Fi would protect LTE-U in all environments under criteria that ignore data submitted to the Wi-Fi Alliance, including data from Wi-Fi vendors. Moreover, the plan is not based on any real, commercial Wi-Fi to Wi-Fi baseline, contrary to the WFA’s own guiding principles for this whole coexistence test plan effort. Instead, it sets a bar for LTE-U that pretends that all Wi-Fi access points are made by a single vendor, even using the same chipset and software release, in identical link conditions, communicating with a few cherry-picked Wi-Fi device models.
“Qualcomm has been actively collaborating with WFA in the test validation process in the Wi-Fi Alliance lab with LTE-U equipment and active testing. The data we collected during the test validation process with the Wi-Fi Alliance staff, which we presented at [Tuesday’s] Wi-Fi Alliance workshop, shows that Wi-Fi access points, including some of the most popular Wi-Fi access points on the market today, do not share spectrum fairly with one another. In addition, the plan even contains a test that has nothing to do with spectrum sharing at all and would convert an optional 3GPP feature into a mandatory requirement on an issue that literally has nothing to do with how LTE-U and Wi-Fi share spectrum. Finally, the latest version of the test plan goes so far as to threaten to cover LAA as well in a future update, even though LAA has already completed a global standards process in 3GPP based upon input from all Wi-Fi stakeholders and even though 3GPP is establishing its own test plan for LAA.
“For all of these reasons, the latest version test plan is unacceptable. It is especially unfortunate since the Wi-Fi Alliance could have produced a plan incorporating our compromise and our other input, but decided not to do so. We believe that the FCC should disregard this latest version of the plan, particularly because the watchword for unlicensed spectrum is supposed to be permissionless innovation, not incumbent protection.”
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