Thinking About Interference

4:45 PM -- If you examine the key barriers to the adoption of WiFi in historical perspective, it started with doubts about the reliability of radio in this application and proceeded to lack of a standard, low throughput, concerns about security, issues with total cost of ownership (TCO), network management challenges, rapid technological evolution and its impact on TCO, and now interference. All of these have been addressed -- but few know about solutions for the last one.

I initially set out to discover if interference really is an issue or not in enterprise settings. I previously published a general White Paper on this topic and a methodology for evaluating the above. (See Thinking About Interference.)

I’ve now applied this methodology to real-world settings and completed testing on the effects of interference on general WiFi traffic, VoFi, and VidFi (that’s video over IP over WiFi). And the answer is yes, interference is already, or is going to be, a problem for many WLANs. Real-world testing revealed that some common forms of interference (like microwave ovens and cordless phones) can in fact be devastating to WiFi -- and can regardless be very difficult to identify. You can read the results in Farpoint Group ’s three Tech Notes, published here, here , and here. But -- cheer up. Good solutions are already available.

The key is to use Spectrum Assurance (SA) tools from companies like AirMagnet Inc. , Cognio Inc. , Fluke Networks , and WildPackets Inc. Farpoint Group owns a copy of Cognio’s Spectrum Expert and we use it frequently. Ultimately, we see SA tools being integrated with the RF Spectrum Management (RFSM) tools used for (among other mundane chores) setting transmit power levels and channel assignments already present in enterprise-class WLAN systems. So, over the next few years, the impact of interference will be minimized to the greatest degree possible. And the next barrier? Whatever it is, we’ll fix that one, too.

— Craig Mathias is Principal Analyst at the Farpoint Group , an advisory firm specializing in wireless communications and mobile computing. Special to Unstrung

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