Many users chalk up WiFi connection problems to congestion, especially when living in apartment buildings or urban areas; there's just too much data being pushed through those 11 meager channels! But a thorough new report (PDF) commissioned by UK regulators sent researchers into the streets to pinpoint WiFi's connection problems, and the culprit turns out to be... baby monitors.

Well, not just baby monitors, of course; any device that shoots radio energy into WiFi's 2.4GHz spectrum creates interference, and it's interference (not congestion) that lies at the root of most perceived problems with WiFi.

The 2.4GHz band actually has quite a bit of spectrum—a full 83MHz between 2.4GHz and 2.483GHz. Teams were dispatched across the UK to check connections in cities of all sizes, but they found congestion problems only in the center of London. Because WiFi is so limited by distance, 83MHz of spectrum proved to be plenty, except in the most densely populated bit of the country.

That's not to say that WiFi is an efficient protocol; it's not. Researchers found that a full 90 percent of all "frames" transmitted by WiFi radios contained only management and node broadcast data. "We have found that it is rare for the user data frame rate to exceed 10 percent of the total frame rate," says the report. Even so, the idea that one's neighbors are "hogging" all the bandwidth in a particular WiFi channel by excessive downloading simply isn't supported by the data.

The culprit for poor WiFi turns out, in almost all cases, to be interference. And it's not generally interference caused by other WiFi radios; the problematic interference is caused most by baby monitors, microwaves, portable phones, and most of all by "audio video senders" (wireless video extenders) which are common in UK apartment buildings.

"The effect of AV senders on WiFi clients is distinctive and repeatable," says the report. "As these devices are inexpensive and readily available in supermarkets, we conclude that the majority of the accusations levelled at residential users for abusing the WiFi networks are actually caused by the installation of AV senders or similar devices. Such devices can easily deprive neighbors of use of a WiFi channel and, at the same time, give the impression of overuse of the channel."

WiFi has become important enough—and the interference problem bad enough—that the report recommends creating a new "2.4GHz friendly" logo program to brand devices that are good radio-frequency citizens. Baby monitors now routinely trumpet their "WiFi friendliness" as a feature, and the new logo program would lay down some principles that every device operating in the 2.4GHz band could follow to make the same claim.