Verizon, T-Mobile Love Unlicensed Spectrum — How Long Till They Kill Wi-Fi?

C.P. McGrowl

By C.P. McGrowl, Chief Channel Curmudgeon

FCC Chairman Ajit Pai has come in for his share of scorn over recent gutting of Net neutrality rules, deservedly in this curmudgeon’s opinion. But most of the tech and business world apparently missed the memo on an earlier decision that could have serious implications. (Ed. note: Channel Partners was there.) I’m talking about the February 2017 announcement that mobile operators will now be allowed to use unlicensed frequency bands, so long as the operators adhere to published FCC technical requirements.

In the cellular world, this development has been referred to as LTE-Unlicensed (LTE-U), and the carriers appear to be most interested in the 5-GHz unlicensed band. Can’t blame them — the 5 GHz band has roughly 500 MHz of spectrum. That’s more than the entire cellular industry has licensed today. And best of all, they don’t have to pay hundreds of millions of dollars for it! The Wall Street Journal reports that both Verizon and T-Mobile plan to launch LTE-U capabilities this spring. AT&T has opted for LTE-LAA (Licensed Assisted Access), which sounds innocuous but also takes advantage of some unlicensed spectrum by aggregating it with licensed spectrum.

While LTE-U is a bonanza for mobile operators, particularly as they move toward small cells that could make good use of those 5 GHz channels, it’s not great news for any business that depends on Wi-Fi, or, by extension, the partners who serve those customers.

Why?

The key element in all radio-based communications systems is radio spectrum. Shannon’s Law (technically the “Shannon–Hartley theorem”) tells us that the amount of bandwidth available on a channel (in RF, “bandwidth” means the same thing as “radio spectrum”) in combination with the signal-to-noise (S/N) ratio, defines the maximum transmission capacity of any communications channel (that is, the maximum number of bits per second it can carry).

In short, without radio spectrum you’ve got no network, and the more spectrum you have (all other things being equal), the more capacity you have to sell.

Unfortunately, not everything is “equal” when it comes to radio. Physics is part of the problem: Not all radio frequencies perform equally. Higher frequencies lose more power over a given distance, which means that a network using higher frequencies requires more base stations to serve the same geography — a major cost issue for providers.

The other problem is law. The FCC regulates the use of most radio spectrum in the United States; other countries have similar regulatory authorities. Each band of frequencies is assigned to a specific application,  such as government, military, aviation, and of course, cellular networks. The cellular carriers traditionally have had to buy their radio spectrum at auctions, and today those assets represent …

… hundreds of millions of dollars on the carriers’ balance sheets.

There’s a good reason a few windows in the radio spectrum were left as unlicensed, which means anyone is allowed to use them so long as the transmitters operate according to technical requirements, such as maximum transmission power, published by the FCC. The availability of unlicensed radio spectrum has given rise to countless wireless products, including cordless phones, baby monitors and garage door openers, among other wireless consumer doohickeys. But for business users, the most important application is Wi-Fi networks.

As the unlicensed 2.4 GHz band used for the original 802.11b and g Wi-Fi networks have become saturated, more and more enterprise Wi-Fi networks are shifting to 802.11n — meaning that, eventually, the cellular carriers could be vying for the same channels you’re using for managed Wi-Fi. They’ll both “work,” technically. but your customer’s Wi-Fi performance is definitely going to suffer.

Initially it appeared there would be major pushback from the Wi-Fi industry, but instead the Wi-Fi Alliance released a Coexistence Test Plan to help LTE-U devices share unlicensed spectrum fairly. That’s all well and good, but at some point, the needs of Wi-Fi users and those of the carriers will come into conflict.

For now, that conflict appears to be sometime in the undefined future, but without doubt, it will come. If we have learned anything in networking it is that traffic always expands to fill the available capacity, and it does so way faster than you thought it would. The carriers’ plans call for them to look for unused unlicensed channels before looking to schmooze in on your existing Wi-Fi network, but I have zero doubt that time will come.

The irony is that for years, one of the big arguments the carriers made for cellular data over Wi-Fi networks was that the cellular networks operated on licensed channels, so there’s no chance that anyone else is going to “walk over” your transmission. Of course, that was always a half-truth (I wouldn’t go so far as to call it “fake news”) because cellular data channels are shared by all of the users in a cell or cell sector, so as more users pile on the shared channel, the average performance for all of them will degrade.

Physics is a cruel taskmaster. People love the capabilities mobile wireless has given them, so wireless data traffic continues to grow unabated. So far, the carriers’ use of unlicensed spectrum has “slipped in” unnoticed, but we can virtually guarantee, and other experts agree, that this is a conflict that will eventually be fought in Wi-Fi networks in hotels, restaurants, convention centers and office parks across the U.S. of A. Don’t say I didn’t warn you.

C.P. McGrowl, chief channel curmudgeon, is a recurring feature on Channel Partners. Since 2018, a rotating cast of characters have used this space to vent about what’s sticking in their craw. The Channel Partners editorial staff pledges to protect the identity(s) of C.P. McGrowl, up to and including a night or two in jail on contempt of court charges. Heck, that would add to their journalist cred. Bring it, DOJ.

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