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How not to get slammed by the FCC for Wi-Fi blocking

Bob Brown | Feb. 11, 2015
Healthcare giant’s wireless communications manager offers advice for navigating WiFi waters.

Marriott's case is one where they assumed they had more of a right to the spectrum than other wireless users. Marriott further assumed they could intentionally interfere with the other users to take control of the spectrum. Marriott was wrong on both counts and the FCC fined them for their mistake. (For more on this story, see "Marriott CIO: FCC message on Wi-Fi blocking loud and clear.")

One other note: some people are complaining that disassociation/deauthentication is not the same as interference. Let's take a closer look at that.

Disassociation/deauthentication by an intrusion protection system works by repeatedly emitting a signal from a Wi-Fi device that causes the target device to disconnect from its network, resulting in a repeated interruption to the radiocommunication service of that Wi-Fi device. The rules say:

15.3 Definitions

15.3(m) Harmful interference. Any emission, radiation or induction that... seriously degrades, obstructs or repeatedly interrupts a radiocommunications service operating in accordance with this chapter.

Comparing the operation of an IPS's deauthentication feature to the definition of harmful interference, it's easy to see that if someone intentionally deauthenticates someone else, the person doing the deauthentication is causing harmful interference. That said, the FCC doesn't require you to share your network with everyone else, so using an IPS to deauthenticate unwanted wireless user devices from YOUR network is legal. Using an IPS to deauthenticate unwanted wireless users from THEIR network is illegal.

The FCC has known about IPS offerings since they first came out. If the Commission believed their existence were illegal, they would have forbade their marketing, importation, sale and use from the very beginning, as they already do with all other forms of jamming devices. The Commission understands IPSes have a legitimate use. Thanks to Marriott, the Commission and everyone else now understand IPSes can have an illegitimate use.

How common do you think the Wi-Fi blocking practices used by Marriott are among other organizations (not just in the hospitality industry)?

Until this happened and wireless engineers began posting their objections on internet sites, I thought this was a rare occurrence. It's pretty obvious now that when the FCC says they're concerned by the number of complaints they've received, they aren't kidding. Not having seen actual numbers, I'm not sure what adjective I would use to describe the magnitude of the problem. It certainly doesn't appear to be an isolated problem, either in terms of raw numbers or in terms of a specific industry.

Why do you think that's the case?

One reason is because very few wireless engineers have read and understand the FCC's rules for operating Wi-Fi systems or other unlicensed devices. The comments being posted certainly support this conclusion. Most Wi-Fi engineers seem to think they only need to concern themselves with microwave ovens, Bluetooth devices and Wi-Fi hotspots. They have no idea they are also required to share the spectrum with amateur radio, remote TV broadcasting, radio-navigation, and others... with Wi-Fi being on the bottom of the regulatory heap. It only takes one careless user, like Marriott, to cause problems for everyone.


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