March 09, 2007, 2:55 PM — It's nice to be back on the pages of wireless.itworld.com, and it suddenly occurs to me that it's been a while. Indeed, I've been pretty tied up with projects, and I've just finished a very large exploration into the nature and effect of interference in the unlicensed bands and how various forms of interference can degrade the performance of wireless LANs. You can find the results in a series of Farpoint Group White Papers and Technical Notes here.
Let me cut to the chase - interference can in fact have a devastating impact on wireless LANs. What we did was define a methodology for evaluating interference, and then perform detailed tests using a number of sources of interference (all of them common devices found in homes and offices) on general Wi-Fi traffic, voice over IP over Wi-Fi (VoFi) traffic, and streaming video over Wi-Fi (VidFi) traffic. Some devices, like Bluetooth headsets, didn't do too much damage. But others, like certain cordless phones, wireless video cameras, microwave ovens, and even other Wi-Fi systems did a whole lot. This adds, if we stop here, a good deal of fire to the argument that mission-critical services shouldn't be deployed in the unlicensed bands (and thus on Wi-Fi) because, well, interference could come out of nowhere and really upset the wireless apple cart. And, to this point, it's been very difficult to detect interference in the first place.
But what I also found was a good number of tools now available from AirMagnet, Cognio, Fluke Networks, WildPackets, and others that enable network operations staff to identify, localize, and remedy interference without too much trouble. I now use Cognio's Spectrum Expert all the time for pre-installation planning, troubleshooting, monitoring benchmark conditions, and spectral and related analysis, and I wouldn't do an installation without it. What I expect to see, over the next few years, is the integration of this capability, which I call Spectrum Assurance (SA), directly into WLAN network management systems, with automated identification and remediation in many cases.
It's safe to assume that, as WLANs proliferate and become the default connectivity for so many users - at home, at work, in the field and on the road - interference is going to become much more of a concern. But we have the tools to deal with this challenge, and they're only to get more powerful and automated over time. Another potential WLAN showstopper derailed.
Anyway, back to work. Let me know what you think. I'll try to stop back and have more for you in these pages in the not-too-distant future.
_______________________
» Evaluating Interference in Wireless LANs: Recommended Practice
» The Invisible Threat: Interference and Wireless LANs
» The Effects of Interference on General WLAN Traffic
» The Effects of Interference on Video Over Wi-Fi
