Wi-Fi Alliance draft test spec is -82 dBm; Verizon wants -72 dBm. Neutral parties think -82 dBm is much too high. These are log scales; even a few dBm are a big difference. Mike Calabrese, one of the best in D.C. claims Verizon-Qualcomm LTE-U plans will interfere with as many as half the Wi-Fi connections unless it backs away well below -80 dBm. (Below) He uses the chart here from Broadcom, which I'm told is based on CableLabs data. New York City says testing on their fast-building LinkNYC discovers problems unless LTE-U backs away if there are signals down to -90 dBm.
Dean Brenner of Qualcomm put out an angry statement that -82 dBm would kill LTE-U, even though neutral parties think it already is too much of a compromise.
(Below) Specifically, -82 dBm would "keep the benefits of LTE-U away from consumers and off the unlicensed spectrum." Given that LTE-U is all about unlicensed spectrum, that's equivalent to saying LTE-U is dead. I also take Brenner's statement "the latest version test plan is unacceptable" suggests he might rally a third of the board members of the Wi-Fi Alliance to vote against it at the September board meeting. This would be a major embarrassment because the LTE-U supporters have been advocating the Alliance test plan as the solution as late as last week.
The board - and the alliance - is entirely from the industry, with no public interest or even neutral academic members I noticed. More than a third are telcos and their suppliers. Verizon, a $250B company, and Qualcomm, a $90B company, almost surely could rally enough votes to overrule the staff decision. They have enormous reason to do so. Qualcomm smells $Billion in royalties. Verizon knows free Wi-Fi is an existential threat to their business model of charging for data volume. The pressure on everyone involved is likely to be enormous. People's jobs and even careers could be destroyed if they vote their conscience.
I wrote an article based on the facts I had, including after requesting contradictory data from Qualcomm, Verizon, and T-Mobile. Late Friday, after a third or fourth request, Qualcomm came through with some data. I have written to some world-class wireless experts to get informed opinion but haven't heard back yet. I'm on an airplane in the morning and not publishing again for ten days. The deadlines are tight, so I wanted to publish what I have.
I'm marking this a "First Look" because of uncertainties introduced when Qualcomm finally made some data available. Here's the Qualcomm presentation. I emphasize that if Qualcomm's data below prove that a test level of -67 to -72 dBm effectively prevents interference with Wi-Fi, then they are right to oppose the -82 dBm test level. No one should translate what I'm writing here into supporting the Wi-Fi Alliance test procedure without having a qualified engineer confirm that Qualcomm's data has not demonstrated that their proposal adequately protects Wi-Fi users.
I normally would have held back writing but Qualcomm pr has inspired literally dozens of articles around the world that reported Qualcomm's claims without verifying data. I haven't noticed any article that actually analyzed the technical dispute. It was primarily about whether Qualcomm's proposed levels actually minimize interference. The better articles presented opposing opinions like Calabrese's but gave readers no way to determine which parties were accurate.
Qualcomm's Brenner: Hoist on his own petard
Qualcomm probably made their task impossible when they agreed that LTE-U should only be approved if it didn't harm Wi-Fi. That meant it would fail if data showed there was harm. Brenner commented, "The record before the FCC demonstrates that LTE Unlicensed has no adverse impact on Wi-Fi" on Qualcomm's own site. “We feel very confident that this isn’t going to harm Wi-Fi in any way and if it were we wouldn’t be doing it,” he also said. This was an almost impossible task; using that much spectrum for a meaningful amount of time almost inevitably would harm any other user of the spectrum. Qualcomm apparently hasn't come close. As far as I can see, they can only live up to that claim on a rigged test.
What will happen next?
The Alliance plans a closed day of tests later in August. Neither press nor the public will have access. The FCC, NTIA, the Internet Society and everyone else who believes in open standards should insist on being observers, and that all test data be publicly disclosed. Sunshine is the best disinfectant, and a party with $billions on the line has been making threats. Remember, the LTE-U folks have not brought this to an open standards group, like IETF or even IEEE. The U.S., including NTIA chief Larry Strickling, has spoken strongly on the need for decisions like these to be made in a "multi-stakeholder" process. At a Columbia event, Larry spoke directly to LAA decisions, saying they should not be made in a corporate only organization like 3GPP.
Any reporter who wrote about this issue owes her readers a follow-up article with the facts researched. I'll share files and sources, and I urge CableLabs, New York City, and of course Verizon and Qualcomm to share actual test data. If Verizon and Qualcomm do not provide adequate test data, I urge the FCC to continue allowing testing of LTE-U but no deployments until the FCC has done adequate testing.
In particular, I urge FCC Commissioner Jessica Rosenworcel to observe the tests, bringing two engineers she respects with her. In 2008, I believe I was the first to report Rosenworcel as a candidate for the FCC; in D.C., that's worth a major favor in return. I've never tried to collect until now, but this one is worth it. I am not urging the Commissioner to see things my way. I respect her because she doesn't do things like that. I'm simply requesting she make the time to examine the technical issues in depth; I trust her to be an honest judge when she has the facts.
The strongest opponent of LTE-U is Qualcomm's Brenner, who has said it should be blocked if it harms Wi-Fi.
From Dean Brenner, Qualcomm. Qualcomm's pr team proved what an $88B company can do to influence the press. The second is from Mike Calabrese
“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 today’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 permission-less innovation, not incumbent protection.”
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 permission-less innovation, not incumbent protection.”
From Mike Calabrese of OTI and New America
WiFu Statement on Wi-Fi Alliance LTE-U Coexistence Test Plan
AUG. 3, 2016
The Wi-Fi Alliance, a broad-based industry group, released its LTE-U coexistence test plan yesterday amidst complaints from the cellular industry, notably T-Mobile and Nokia, that the process is taking too long and is biased against the use of LTE licensed technologies on unlicensed spectrum bands. LTE-U proponents serve on the Wi-Fi Alliance board and late last year asked the group to convene a collaborative process to test whether LTE-U would unduly disrupt millions of existing Wi-Fi deployments in businesses, public places, schools and homes across the country.
In response to a FCC Public Notice last year, New America's Open Technology Institute (OTI) and other public interest groups warned that Verizon and other mobile carriers have every incentive to use LTE-U to undermine Wi-Fi, thereby squelching competition from Wi-Fi first carriers and charging subscribers for video and other data traffic that consumers now receive free or at minimal cost over unlicensed bands by using Wi-Fi.
The following statement can be attributed to Michael Calabrese, director of OTI’s Wireless Future Project:
Consumer advocates are heartened to hear the Wi-Fi Alliance has completed its LTE-U coexistence test plan. However, it is alarming to hear that compromises on the test plan within this industry group could leave 50% of Wi-Fi connections at risk of disruption from LTE-U.
It is also unfortunate that cellular industry proponents of using LTE on unlicensed spectrum are now threatening to pull back from Wi-Fi coexistence testing they initially proposed and supported.
We call on the FCC to ensure that all implementations of unlicensed LTE devices pass the entire test and coexist fairly with Wi-Fi. The test results will help the FCC decide if LTE-U, which will be controlled from licensed spectrum bands, can coexist with Wi-Fi, the unlicensed technology that has proven critical to schools, consumers and the U.S. economy as it carries 80 percent of all mobile device data traffic.