“Now that WiFi access points can cost under $100, the technology has jumped quickly from esoteric to everyday. And as more consumers learn the convenience of untethered Internet access, they’re also learning what things can stop WiFi from working.
Traffic jams are at the top of that list: When multiple WiFi access points, the hubs of individual wireless networks, sit near each other, WiFi receivers can see senseless noise instead of a clear data stream. This is what happened at the CeBIT computer trade show in Germany last year, where a maze of overlapping WiFi networks stopped many laptops from getting online.
MobileAccess Networks, a Vienna-based firm that installs cellular and WiFi networks inside office areas, regularly runs into this issue. The company uses software originally developed by WiFi enthusiasts to sniff out open wireless connections — not to find free Internet access, but to know what WiFi channels to avoid when setting up wireless networks in clients’ offices.
The treatment for WiFi interference should be familiar to anybody who has wrestled with an old analog cordless phone: Change the channel. The WiFi standard most people use, called 802.11b in technical jargon, allows for 11 different frequencies, clustered around the 2.4 GHz band.
WiFi experts, however, generally recommend choosing from only three of these channels — 1, 6 and 11 — to ensure there’s enough room between to avoid interference.
Matthew Gast, author of a book about WiFi and an engineering consultant with Trapeze Networks, a California-based company that builds wireless networking equipment, said he didn’t think that most people would encounter Kastner’s gridlock scenario — they live sufficiently far apart. But in densely developed areas with many Internet users, problems can arise.
He related a story he’d heard about one Florida suburb where so many signals jammed each other that residents formed an ‘ad hoc neighborhood spectrum allocation committee” of WiFi users.’”
More at http://www.washingtonpost.com/wp-dyn/articles/A38700-2004Apr24.html