WiFi firmware that can detect and route around interference from non-WiFi devices

In Airshark: Detecting Non-WiFi RF Devices using Commodity WiFi Hardware (PDF), researchers from U Wisconsin (Madison) document a firmware for WiFi access points that can detect and dynamically adjust to interference from vacuum cleaners, baby monitors, and other non-WiFi devices that operate in WiFi's radio spectrum. This kind of thing is the backbone of the theory of cognitive radio: devices that can use software defined radio, phased-array antennas, and cleverness to route around other devices in the band, which may, eventually, enable the a lot more data to occupy the radio spectrum. In Airshark's case, the cleverness is in using the wireless cards on the computers and other devices as a sensing array to triangulate on interference.

Airshark taps into the application programming interface of wireless cards used on access points to gather data about radio frequencies in the surrounding environment. The software has been trained to recognize signatures of various devices, and can pick them out from the ambient radio noise with more than 90% accuracy even if signals from multiple such devices are present.

False positives were .39% for environments with four or more interfering devices and using various signal strengths. The researchers found the rate was .068% for signals stronger than -80dBm. "We also found its performance to be comparable to a commercial signal analyzer," according to their research paper "Airshark: Detecting Non-WiFi RF Devices using Commodity WiFi Hardware."


    1.  what would it take for me to convince you to stop reheating your coffee. My primary arguments are that microwaving coffee causes your AirTunes to cut out, wrecks the flavor of coffee, and making coffee one cup at a time is pretty efficient in terms of taste and waste. 

      1. If its cutting your wifi out, sounds like there is microwaves escaping. Don’t keep your face pressed aganst the glass whilst waiting for your coffee buddy :)

        1. Microwaves produce around 1000W of broadly tuned RF centered in the 2.4GHz range. FDA acceptible leakage is up to 5 mw/sq cm @ 5 cm from the oven. That won’t cook your brain, but it might raise the noise floor enough to completely jam  your Wi-Fi.

          1. While thats true, it doesn’t really matter all that much when the design of microwave ovens centers the megatron on the side of the oven so not to zap people with an open door anyway. Its a moot point, but my original comment was for jest.

    2. Are they on the same circuit in your house?

      I live in a fairly old house with old wiring and not every plug has excellent grounding.  If I plug in a radio and battery charger for my power tools into the same circuit the radio goes to almost complete static (if something is actually charging).  Could just be a grounding issue rather than an interference thing.

      But I have seen plenty of cases where it certainly is the microwave causing EM interference as well.

  1. And all I can think is, “thank fuck they named it something good (AirShark), and not an incomprehensible mess of uppercase letters (WRFPDTXYZAWMLXI)”. Still, it’s promising tech.

  2. They do detection, but there is no dynamical adjustment of any protocols due to the interference, and it does not triangulate anything. The authors only suggest this could be done in future implementation.

  3. I’m kind of excited by this (I work in the field). There are enterprise class solutions that do something similar, but using the APs themselves or dedicated wireless sensors(they take spectrum samples every n ms). This will allow a wireless controller switch to adjust the various AP power levels and channels as needed to “heal” coverage gaps. In practice it works… sporadically. Each iteration is just a a little better.

    This is a great idea. Rather than dedicated sensors or having AP spend small slices of time not being an AP, you can use the plethora of clients to make measurements. Larger sample data and more points reporting in… you can make much finer and accurate adjustments to your field coverage. I hope they make an API available to hook in some kind of central management.

    This is neat stuff.

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