The FCC recently ruled against Marriott for blocking customers’ access to WiFi generated by the cellphones. Guests who tried to use their own WiFi were deauthenticated so that the only WiFi option available was to use the one sold by the hotel, for a hefty daily fee. The Marriott Wifi engineers testified that they had done this to protect against interference to their own WiFi networks for paying customers. But the FCC ruled against Marriott and told them to stop blocking customers.

My gut feeling is that Marriott was doing this for the money, because they must have gotten a ton of customer complaints and it’s hard to think that they continued to back their IT engineers over the public. But as the FCC ruling made clear, it didn’t really matter why Marriott did it. There is no valid reason to block WiFi.

What Marriott failed to realize is that WiFi is truly a public spectrum. And while it is open to everybody, it also comes with some rules about how the public is allowed to use it. The FCC spectrum rules are clear on this, but I suspect that even many industry people have never read them. Certainly the manufacturers of WiFi devices don’t educate their customers very much about the obligations of using the spectrum.

The following portions of the FCC rules, although written in tech-speak, sum up the WiFi obligations:

§15.5   General conditions of operation.

(a) Persons operating intentional or unintentional radiators shall not be deemed to have any vested or recognizable right to continued use of any given frequency by virtue of prior registration or certification of equipment, or, for power line carrier systems, on the basis of prior notification of use pursuant to §90.35(g) of this chapter.

(b) Operation of an intentional, unintentional, or incidental radiator is subject to the conditions that no harmful interference is caused and that interference must be accepted that may be caused by the operation of an authorized radio station, by another intentional or unintentional radiator, by industrial, scientific and medical (ISM) equipment, or by an incidental radiator.

What these rules mean are that nobody has any more right to use the WiFi than anybody else. It does not matter if you are the first one using the spectrum in an area – everybody else has the right to use the spectrum in that same area as well. Further, you are allowed to use spectrum as long as you don’t harm other users, with the caveat that lawful interference must be accepted. With most licensed spectrum bands no interference is allowed. But WiFi, by its very definition as a public spectrum, can have mountains of interference and still be operating within the law. So when the rules say that you can’t cause harmful interference, this is interpreted for WiFi to mean that you can’t somehow stop others from using the spectrum – but that normal interference with WiFi is perfectly lawful and expected.

The Marriott engineers also tried to argue that deauthentication is not the same thing as interference. The system they were using repeatedly sent out signals that stopped WiFi users from staying connected to their cellular WiFi networks. Marriott says they weren’t blocking the spectrum, just the use of the spectrum, a very fine distinction that the FCC also didn’t buy.

And so the Marriott engineers were wrong about a few very basic rules of spectrum usage. They had no more right to the WiFi spectrum inside the hotel than any of their customers. And it doesn’t matter if customer use of WiFi from cellphones interferes with Marriott WiFi, since the cellphone WiFi is lawful and the interference is legally acceptable.

This is a caution to anybody who wants to use WiFi in a commercial application. Whether you are a wireless ISP (WISP), a hospital, an airport, or a coffee shop, you have no more right to the spectrum than anybody else. Again, this is something that the makers of WiFi equipment don’t tell their customers, or at least not outside of the very small print. If you really need interferences free transmissions, you ought to be looking for a different spectrum to use. There are absolutely no guarantees with WiFi, regardless of what the claims of the vendor who sold you your gear.

There have been several attempts over the years to build large public outdoor WiFi networks. Almost by definition these networks are going to fail, or at least perform incredibly poorly in some places. Such networks have to compete against every home router, public hotspot and other uses of the spectrum in the same area. Further, like cellular networks, WiFi networks can become overloaded with too many simultaneous users.

Some of us are old enough to remember the days when the 900 MHz spectrum got overloaded. This is are also free public spectrum and it was originally used for everything from cordless phones to garage door openers. It got so overloaded that eventually you couldn’t hold a 900 MHz phone connection long enough to finish a call. Because it seems like everybody has a plan to use WiFi that the day might come whenthis spectrum will also get overloaded in some places. And the only real solution for this will be for the FCC to provide more public spectrum. Because WiFi interference is lawful and expected, as much as users might hate it.