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7 WiFi Killers That May Surprise You

  • If you're interested in WiFi, love Christmas decorations -- or both -- you probably noticed recent reports out of the United Kingdom that your active holiday decor may be disrupting the WiFi signals in your home or business. Whether the impact is the result of shoddy electrical design by the manufacturers of the fairy lights (as they say in the UK) or a more sinister collusion between wireless router makers and the Christmas light industry to sell more wireless hardware is certainly a question that hangs in the air.

    Are ugly, light-up sweaters responsible for mobile denials of service? That one is still being investigated, but there is one clear truth that wireless experts already know regardless of the holiday light dust-up: Non WiFi products very much can make wireless life miserable.

    Without diving too deep into the technology, we can boil the problems down to a couple of regulatory realities. WiFi works in the unlicensed 2.4-GHz and 5-GHz frequency ranges. There are many other devices that also leverage the fact that you can transmit in these spectrums without expensive and complicated licensing requirements.

    In addition, all the wireless devices that tend to step on each other are required to tolerate interference, unless you can change their channel to a non-polluted one within their operational profiles. In other words, interference is a fact of life under the current rules. Now that you know about pretty lights with evil intentions, let's take a look at a number of other common interferers that you may not be aware of.

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  • Bluetooth can make you blue

    Bluetooth devices work in the 2.4 GHz spectrum, where we find 802.11b, g, and n WiFi. Most Bluetooth devices are innocuous, and built to be good neighbors by avoiding active WiFi channels. But older versions of Bluetooth weren't so friendly and could be disruptive to WiFi users in the immediate area. And if you get a lot of Bluetooth devices all in the same room, the laws of physics say that your 2.4 GHz signal will be impacted. Whether the impact is perceptible or not will vary by individual scenario, but if your WiFi is wonky, try checking the headsets, Fitbits, and keyboards at the door.

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  • When WiFi gets nuked

    The microwave oven is the absolute Godfather of Interference at times. The high-power transmitters in microwave ovens not only warm up your holiday cocoa, but they put a really interesting wideband interference signature on spectrum analyzers and wireless intrusion prevention systems. They make for easy demonstrations of interference in wireless classes, but can drive you nuts when they disrupt your streaming video while coworkers are nuking their burritos. Not all microwave ovens are guaranteed to cause trouble, but as these handy appliances age, and seals and shields break down, they can be surprisingly nasty to WiFi. Generally, microwaves cause more problems with 2.4 GHz than 5 GHz.

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  • Hold the phone!

    Cordless phones can be hard on both WiFi bands. It's further complicated by the fact that when you shop for cordless phones they may not mention anywhere on the packaging that it uses 2.4 GHz or 5 GHz frequencies. But when you start using it, the interference may be devastating to both bands. Cordless phones may seem passé to you, but if they are still an option in your home or business, be sure to purchase units that are clearly labeled as based on DECT 6.0 technology. DECT 6.0 works at 1.9 GHz, and couldn't interfere with WiFi if you wanted it too.

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  • Gadgets galore

    When it comes to interference training for WiFi administrators, assorted gadgetry operating at 2.4 GHz is standard fodder. The list is long: baby monitors, garage door openers, wireless microphones, display mirroring devices, drones, remote control toy cars, and a lot more. If it's "wireless," it may well be built to leverage 2.4 GHz or 5 GHz. There's no real way to know unless you look up specific model numbers, and sometimes you have to go all the way to the FCC's database of registered products to find a spec. If your wireless is acting flaky, take inventory of everything in the area that transmits via wireless and sleuth out their operating frequencies. You may find a culprit in the mix.

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  • Pull those plugs

    "Wall-wart" power supplies are those cheapie AC adapters that either power or charge an endless range of devices, including many discussed in this article. Amateur radio operators and RF engineers know well the interference damage that these mass-produced, low-quality disposable power supplies can wreak. They can be brutal to diagnose and easy to look right past. It helps to have a spectrum analyzer that can show you signals in the air. But when a cheap power supply is radiating wideband noise, an easy test is to simply unplug it and see if your WiFi problem goes away.

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  • Beware the bad guys

    Finally, don't discount the "bad guy" factor. There are a fair number of wanna-be hackers and penetration testers out there that have access to illegal, but easy to get, interference-generating devices that can lay waste to WiFi cells. The same thing can be done with a high-powered WLAN adapter purposefully configured to be malicious. If you live out in the sticks, you probably don't have to worry about this one, but when you're in a dense apartment building or even a busy wireless hotspot area, you never know when a knucklehead is going to try to prove his "skills."

    (Image: Mikko Lemola/iStockphoto)