An LTE over Wi-Fi spectrum grab is coming

Pundits say spectrum demand will overrun supply by 2018 or 2019. Grabbing someone else’s frequencies would be one solution.

lte lead image

Unlicensed spectrum would be the logical place to expand traffic if, as mobile networks are finding, their licensed spectrum is running out.

Why not shift over to unlicensed spectrum? It's unlicensed, after all, so anyone can use it. Who would object?

Well, the answer to that question may be a bunch of Wi-Fi users, like you and me, if it doesn't work as promised and stomps on existing use, such as Wi-Fi.

Wi-Fi at 5 GHz

The new piggy-backing technology uses the same Wi-Fi band that mobile device users are beginning to take advantage of in the home and workplace. That is 5 GHz—the free-to-use band you'll find in newer routers and mobile devices, like tablets and recent phones.

Five GHz Wi-Fi is underused, fast, and well-suited to media delivery in small spaces, like the home. That's why new mobile devices use it.

And it appears Mobile Network Operators (MNOs) have taken a fancy to it too. But in that case it's likely for paid-for use in phones.

License Assisted Access

The new technology works by combining existing mobile network spectrum with low-power Wi-Fi spectrum to create a bigger pipe. The technology uses micro-cell-like mini antennas.

It's interchangeably called LTE-U, which stands for LTE-Unlicensed, or its new name LAA, or License Assisted Access.

Remarkably, that new name sounds more like an altruistic, social government program. The new moniker even manages to change elements of the name from "unlicensed" to "licensed." There's a reason marketing experts get paid what they do.


And there's a reason LAA needs to tread lightly. Wi-Fi Alliance, the Wi-Fi trade body, says LAA poses a risk that could negatively impact "billions of Wi-Fi users who rely on 5 GHz," and that "more work needs to be done."

Ericsson has just said its LAA roll out will begin in Q4 2015.


Wi-Fi band rules say users can't cause interference. It's not allowed. The MNOs and equipment makers insist that LAA won't cause interference.

And maybe that indeed will be the case. Radio signals are better aimed these days, and interference minimization does in fact tie in with an industry trend where frequency waste is increasingly minimized through algorithms and other beaming techniques. Ericsson and Qualcomm are innovative leaders in RF technology.

Interference has historically been created by frequencies stepping on each other—a kind of overlapping caused by a lack of targeting. Clean it all up and there's more capacity through less interference.


Ericsson says it can obtain speeds of 450 Mbits using both the LTE spectrum that the carrier has paid for at great expense, usually at a government auction, and this unlicensed band it's plucked for free.

Initial users will be Verizon and T-Mobile, among others, says Sarah Thomas in LightReading, a telecom publication.

"Rude" technology

The big question, of course, is the interference issue. If Qualcomm and Ericsson, the two main players, can get LAA to work flawlessly on the increasingly popular public frequencies they're purloining, as they say they can (and have shown in the lab), then kudos to them. They've improved society.

If, on the other hand, LAA "takes over the band it operates in" and causes Wi-Fi devices to "experience degraded service, service interruptions, and/or complete loss of their connections," as an article by Tinaya in the blog WorldTVPC described as a worst-case scenario, then there'll be trouble. Not least from me. I live on a hilltop, and microwave 5 GHz can travel a long way via line-of-sight with no obstructions.

To add insult to injury, we may all be paying for that stomping in our wireless bill too.


Copyright © 2015 IDG Communications, Inc.

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