Killing My WiFi (With This Song)

Spec-ing the Layers with WiSpy
(one time, one time)
Channel gone red with this stream
(two times, two times)
Killing my channel with this song
Killing my WiFi
With this song
Taking my WiFi
With this stream
Killing my WiFi
With Bluetooth spe-ee-ee-eeakers...

Wireless streaming (music, video or, in the case of the wonderful song referenced above, a music video) can sure kill a WiFi connection.  It's good to have a spectrum analyzer to identify the problem.  It's even better to remember to use it.

Wireless streaming devices are popular nowadays, but most of them are benign.  An AppleTV, for instance, can wirelessly stream audio and video or it can act as a mirroring device for whatever audio or video is on your smartphone, tablet or laptop.  (And mirroring is tougher on WiFi than basic streaming.  When I mirror my iPhone 5, I'm creating three streams.  One from my wireless router to my phone for the Internet stream, a second from my phone back to the wireless router as part of mirroring and then a third from my wireless router to my AppleTV, also as part of mirroring.  Mirroring is a real bandwidth hog.)  When I stream or mirror to an AppleTV, the wireless audio or video is all using WiFi.  The 802.11 standard (which is what WiFi is based on) has excellent sharing protocols built in, so that my other WiFi devices don't get killed by my streaming or mirroring.

Non-WiFi streaming devices can be a big problem.  Sonos systems, for example, are commonly set up using a non-WiFi wireless technology.  In fact, if Sonos audio is used as part of a home theater, non-WiFi wireless is required.  Sonos, and many other non-WiFi streaming systems, use the 2.4 GHz frequency band.  Some speakers may use Bluetooth and some may use a proprietary technology, but it's almost all 2.4 GHz.  And when it's in the 2.4 GHz band and it's not WiFi, then it doesn't share the way 802.11 devices do.  It creates interference.

So, what to do about 2.4 GHz interference?  First of all, don't do what I did when I was trying to help a friend set up his WiFi recently.

My friend is paying for 150 Mbps Internet download speeds, but he was getting less than 1 Mbps.  He was using a wireless modem from the phone company, and the wireless modem is a model that I've had problems with before.

I was faced with an important choice:

A) Troubleshoot like a professional by working my way up the OSI layers.  Start with the physical layer by running a spectrum analyzer (I use Metageek WiSpy 2.4x with Chanalyzer software.  Lots of people use WiSpy DBx because it allows for analysis of the 5 GHz band, but that is unnecessary and can sometimes even be counterproductive).  Then move to the MAC layer by checking devices' WiFi Settings and possibly using a Protocol Analyzer.

B) Act like I know everything and complain to the phone company about their crappy wireless modem.

Naturally, I chose B.  After wasting hours on the phone with the phone company (hours that we were supposed to be spending seeing "Top Five" before the Kings vs. Maple Leafs game), I finally set up a 5 GHz radio with a separate SSID and saw the Sonos interference magically (not magic, of course, because Sonos systems only ruin the 2.4 GHz band) disappear.

The moral(s) of this story?

1) Avoid acting like a know-it-all when troubleshooting wireless problems.

2) Start with a quick spectrum sweep if audio/video streaming is happening nearby.

3) Don't sleep with your co-star if you don't want to get divorced.

One last little note: I'm often a critic of spectrum analyzers.  I see people (people on Twitter, people on blogs and especially people in real life) use them incorrectly all the time.  "If you're looking at Duty Cycle, you're in the wrong place," is a saying that I like using when it comes to using spectrum analyzers in WiFi environments, for example.  But spectrum analyzers are darned good for one very specific use: identifying things (speakers, microphones, security cameras, microwave ovens) that are killing your WiFi (with or without this so-oo-ooooong).


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ben at sniffwifi dot com

Twitter: @Ben_SniffWiFi


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