Qualcomm CTO: LTE, Wi-Fi need to work side by side

SAN DIEGO, Calif. -- Qualcomm (NASDAQ:QCOM) hosted a media event at its headquarters on Wednesday as part of its ongoing efforts to "set the record straight" about LTE Unlicensed (LTE-U) and Wi-Fi coexistence, with the bottom line being: If you want to improve the quality of Wi-Fi, your best bet is to develop and deploy LTE-U sooner rather than later.


Qualcomm's slogan is "Why wait?" and when it comes to LTE-U, the Wi-Fi community, including the Wi-Fi Alliance, National Cable and Telecommunications Association (NCTA) and companies like Google (NASDAQ: GOOG) are advocating for a slower migration -- and one where the Wi-Fi Alliance, for one, can have more say over on how it ultimately comes out.

But Qualcomm representatives, including CTO Matt Grob, suggest the push-back by cable companies and the Wi-Fi community is merely a delay tactic. In their view, consumers want better Wi-Fi – after all, who hasn't had problems connecting to Wi-Fi at trade shows or in a packed sports stadium? Plus, Wi-Fi access points in hotels and other venues are often insecure and can expose consumers to hackers.

During a Q&A with reporters, Grob said Qualcomm has a vested interest in both Wi-Fi and LTE, and both sides within Qualcomm's R&D are drawing from one another in refining the technologies. "Actually, a lot of them get along," Grob quipped. He also described a future in which there will be a combination of LTE and Wi-Fi, with ports for either mode, as a precursor to what's going to happen with 5G.

While touring the Qualcomm facilities, Mingxi Fan, vice president of engineering, corporate R&D at Qualcomm Technologies, guided reporters through the stress testing that Qualcomm conducts in its LTE/Wi-Fi coexistence test chamber. The tests show that when LTE-U is introduced to the environment, it makes Wi-Fi perform better rather than degrading it.

And while there's a lot of talk about the "listen before talk" requirement that is to be addressed in the 3GPP version of Licensed Assisted Access (LAA) and Qualcomm engineers do abide by regulations, from a design and engineering perspective, the regulations call for an absolute minimum, and that's not sufficient. "We really have to go above and beyond" the regulatory requirements, Fan said.

Qualcomm representatives stressed that merely introducing LTE into the unlicensed 5 GHz spectrum used by Wi-Fi isn't what they're proposing. Rather, they're making specific adaptations to LTE in order for it to coexist in the same spectrum that Wi-Fi devices use.

LTE-U proponents also say LTE-U has a feature called an "adaptive duty cycle" that allows it to take turns with other users. If another user is operating on an unlicensed frequency, LTE-U can still operate on the same spectrum without degrading the other user's performance. Using a technique known as Carrier Sensing Adaptive Transmission (CSAT), LTE-U senses the traffic on a particular channel, such as data on a Wi-Fi access point, and measures how frequently it is occurring. Depending on the amount of traffic and the pattern of that traffic, CSAT will schedule bursts of traffic during the time intervals when no other traffic is present.

As Verizon (NYSE: VZ) sees it, the first market it wants to target with LTE-U involves in-building enterprise deployments, where users expect and are more likely to pay for a higher quality of service. While U.S. carriers are using Wi-Fi for offload, thereby lifting some of the traffic demands off cellular, Verizon is talking about doing offload in such a way that it will be better able to guarantee a certain level of service by employing LTE-U. 

Patrick Welsh, assistant vice president, wireless policy development at Verizon, said the operator had questions about LTE-U from the beginning and wondered whether it would have a negative impact on Wi-Fi. Verizon sells millions of smartphones, FiOS routers and other products that have Wi-Fi built in, and it also has an interest in making sure that if it deploys one technology, it doesn't undermine another, he said. Verizon formed the LTE-U Forum to go "above and beyond" the regulatory requirements to make sure there would be no negative impact on Wi-Fi.

When the LTE-U Forum released its first specs on March 2 and sought feedback, that was the start of a public dialog and peer review. A series of meetings and workshops followed, with the idea that the forum would be as transparent as possible, according to Welsh. The results also were shared with other carriers, and T-Mobile (NYSE:TMUS) was one of the first to get on board with the technology.

If Verizon Wireless can boast about the quality of its network and its relatively good spectrum position, why is it in such a hurry to deploy LTE-U before the standardized Licensed Assisted Access (LAA) becomes available? "We are in a good position," Welsh told FierceWirelessTech. "But we can't rest on our laurels because our competitors aren't. If you stand still, you will fall behind." 

Qualcomm's media event occurred the same day Qualcomm, Verizon, T-Mobile, Ericsson (NASDAQ: ERIC) and Alcatel-Lucent (NYSE: ALU) sent a letter to the FCC urging the commission to reject the Wi-Fi Alliance's "unprecedented" request to withhold certification of any LTE-U equipment until the Wi-Fi Alliance develops a coexistence test plan and completes its own evaluation program on LTE-U's impact on Wi-Fi.

Dean Brenner, senior vice president of government affairs at Qualcomm, said the FCC is doing its job by asking appropriate questions and the LTE-U Forum has no problem with that, but it's a little odd because Qualcomm and Verizon both are members of the Wi-Fi Alliance, yet the alliance did not approach them about doing a workshop or its own coexistence evaluation program -- Qualcomm and other LTE-U Forum members only learned about it when the alliance filed its Aug. 14 letter with the FCC.

For its part, the Wi-Fi Alliance isn't backing down, saying it stands by its recommendations to the FCC and pointing to research that shows the current version of LTE-U would negatively impact Wi-Fi networks.

Related articles:
Verizon, T-Mobile and other LTE U supporters castigate Wi-Fi Alliance certification proposal
T-Mobile accuses cable companies of using LTE-U tests that rely on extremes, not reality
With 4 standards cooking for LTE Unlicensed, FCC tech chief asks for more details on Verizon's CSAT
T-Mobile champions co-existence amid calls for FCC intervention in LTE-U