FCC Gives the Green Light to LTE-U: Move Over Wi-Fi

In his first major move since assuming the chairmanship of the FCC, Ajit Pai announced the agency's first authorization for the use of LTE-U (LTE-Unlicensed) devices operating in the 5-GHz unlicensed band. Both Verizon and T-Mobile plan to launch LTE-U capabilities this spring, The Wall Street Journal reports.

I've written on the subject of LTE-U before, in particular, its potential impact on other users of the unlicensed 5-GHz band, which would include enterprise Wi-Fi networks using 802.11n and 802.11ac. While 802.11n could operate in either the 2.4-GHz or 5-GHz bands, 802.11ac is designed for 5 GHz only. Given the power limits on 5-GHz transmissions and the signal loss at those frequencies, LTE-U will be a small cell technology exclusively, augmenting the carriers' macro networks in areas of heavy usage.

Wi-Fi & LTE-U Communities Come Together

When the idea of LTE-U first surfaced, it developed into something of a shoving match between the mobile operators and the Wi-Fi industry. On the mobile operator side, the first group to coalesce was Evolve, fronted by AT&T, Verizon, T-Mobile, Qualcomm, Nokia, Ericsson ... you get the picture. However, it focused on cooperation and coexistence, noting in its principles, "New technologies using unlicensed spectrum need to work cooperatively with Wi-Fi today, tomorrow and into the future."

A second group called the MulteFire Alliance with many of the same members has also stepped into the fray and is developing a specification for an LTE-based technology for small cells operating solely in unlicensed spectrum. The 3GPP, the group that develops standards for the cellular industry, has also weighed in on the use of unlicensed spectrum.

Fronting the battle for the Wi-Fi side has been the Wi-Fi Alliance, with support from Google and a number of cable operators, many of whom have built extensive public Wi-Fi networks for their customers. While the relationship appeared to be somewhat rocky at the outset, the Wi-Fi and LTE-U communities eventually came together, and in September of last year, the Wi-Fi Alliance released a Coexistence Test Plan to "help ensure LTE-U devices can demonstrate they share unlicensed spectrum fairly and will serve as a valuable tool for vendors and service providers seeking to improve how their deployments coexist with Wi-Fi networks.

In a statement released today, Kevin Robinson, VP of Marketing for the Wi-Fi Alliance said, "[The] Wi-Fi Alliance is encouraged to see LTE-U device vendors following through on their commitments to test devices against the Coexistence Test Plan through qualified independent test laboratories to demonstrate their LTE-U products share spectrum fairly. The successful application of the Coexistence Test plan validates the significant investments made by both the Wi-Fi and LTE-U communities."

While Wi-Fi and LTE-U will "coexist," the actual impact on private Wi-Fi networks remains to be seen. The coexistence strategies depend on Wi-Fi and LTE-U devices potentially taking turns using the same channel, which would most certainly have an impact on Wi-Fi network throughput. However, that channel sharing would be a last resort as the LTE devices would look to the carrier's licensed channels first, then unused 5-GHz Channels, and finally shared channels.

This is indeed a big, if somewhat ironic, win for the mobile operators. Big, in that the carriers now have access to hundreds of megahertz of unlicensed spectrum they don't have to pay for. Ironic, as the mobile operators had formerly looked disparagingly on unlicensed spectrum and touted the benefits of owning licensed spectrum that was guaranteed to be free of interference.

However, mobile data traffic continues to grow, and in this highly competitive market, Verizon and AT&T have now reintroduced "unlimited" data plans. Unlimited is in quotes because there are always limits in one way or another, generally in the form of speed reductions once a defined usage threshold has been passed.

People love the communication, information access, and entertainment options mobile networks can provide, and they seemingly can't get enough of it. One of my favorite tenets for network traffic has always been, "Traffic always expands to fill the available capacity - and three times faster than you thought it could!" With mobile operators now creeping into the unlicensed spectrum, I just wonder where they will go looking when we hit the next capacity crunch.

Learn more about mobility trends and technologies at Enterprise Connect 2017, March 27 to 30, in Orlando, Fla. Michael Finneran will be exploring this topic further in the session, "Mobility 2020: Where the Mobile Enterprise Is Headed," which is part of our one-day program on the future of communications and collaboration. View the Mobility track, and register now using the code NOJITTER to receive $300 off an Entire Event pass or a free Expo Plus pass.

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