Can You (Legally) Control Rogue Devices On Wi-Fi?

Radio-frequency interference is the carbon monoxide of the wireless world – invisible, tasteless, odorless, arriving without warning, and with the ability to really ruin your day – unless you know the symptoms and have the right tools at your disposal. And that’s just what we have for you in this new series of articles from noted wireless expert Craig Mathias of Farpoint Group.

You may recall from the first article in this series that governmental regulatory authorities like the FCC set aside the unlicensed bands for low-transmit-power devices that are willing to accept any interference present while operating. This seems to imply that anyone could come into your facility with any kind of wireless device and feel free to power it on even, if it causes interference, unintentional or not, to your Wi-Fi and other wireless systems.

In practice, though, you have a lot of control over your local airwaves. Up to a point, anyway.

A recent FCC decision involving the Marriott hotel chain scolded (and then fined!) the firm for forcibly disassociating Wi-Fi clients, in what was pretty clearly a move designed to get those clients to use Marriott’s own fee-based Wi-Fi service. Marriott claimed interference as a justification for its actions, but was regardless rebuked. This would seem to indicate that even steps taken against rogues might be called into legal question.

Can you prevent rogue devices on your WLAN?

While as a practical matter intrusion detection and prevention solutions are still allowed, we expect the FCC to clarify ultimately the fundamental issues here. Because one of the best ideas circulating about dealing with interference involves the application of common sense to the challenge at hand.

Suppose you own a convention center. The radio environment can be nothing short of chaotic, especially during network-equipment-industry events, and your own Wi-Fi service, which likely today hosts a number of mission-critical applications, may be seeing interference so severe as to compromise its function and mission.

This has nothing to do with getting more guests to pay for the use of that network; it’s more about fundamental survivability. You may recall that Steve Jobs, during the iPhone 4 announcement, actually requested the audience to turn off their Wi-Fi devices so he could do a simple demo. It’s that kind of issue. 

So – suppose a given facility could simply state, as a matter of policy, that only certain devices could be used within its walls. Rules would be posted at the entrance to the facility, and enforced using the same intrusion detection and localization technologies already widely deployed today. Even though this all seems to run counter to the spirit of the rules regarding the usage of the unlicensed bands, we believe this is the single best idea out there today – and we also believe that the FCC will ultimately support this concept as long as its applied in limited geographic areas and in a non-discriminatory and uniform fashion.

What else might you do? Well, there’s a huge amount of unlicensed spectrum available at 60 GHz. – roughly seven times the amount of spectrum available at 2.4 and 5 GHz. combined – and an IEEE standard, 802.11ad, addressing its use. The Wi-Fi alliance is hard at work developing specifications here, which we expect by next year.

Yes, these transmissions don’t go through walls very well, but should be just fine in open-office environments. The huge amount of spectrum available will provide not just high throughout, but also high capacity – and the directional nature of these transmissions means less opportunity for interference.

Future of Wi-Fi

And you thought the Wi-Fi space was slowing down and even maturing… No, we continue to meet opportunities and challenges with the same spirit of innovation that has defined wireless LANs over the past quarter of a century. We have the tools, and now you have the knowledge – interference is a fact of life in wireless, but by no means does it point to the end of the road.

In future series, I’ll be talking more about the future of Wi-Fi. Stay tuned.

All Posts In This Series:

Solving The Next Great Wi-Fi Challenge: Interference
RF Detection: Solving The Next Great Wi-Fi Challenge

1) Solving The Next Great Wi-Fi Challenge: Interference

2) RF Detection: Solving The Next Great Wi-Fi Challenge

3) Why LTE-U Is The Next Great Interference Threat To Wi-Fi

4) How BYOD Policies Can Help Deal with BYOD-Related Wi-Fi Interference

5) Can You (Legally) Control Rogue Devices On Wi-Fi?


Craig J. Mathias is a Principal with Farpoint Group, an advisory firm specializing in wireless networking and mobile IT. Founded in 1991, Farpoint Group works with technology developers, manufacturers, carriers and operators, enterprises, and the financial community. Craig is an internationally-recognized industry and technology analyst, consultant, conference and event speaker, and author. He currently writes columns for Boundless, Connected Futures,, and various sites at TechTarget. Craig holds an Sc.B. degree in Computer Science from Brown University, and is a member of the Society of Sigma Xi and the IEEE.

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