Wi-Fi slowed by interference, not congestion

Problems with Wi-Fi performance tend to be the result of interference from other devices using the same frequency, rather than mutual congestion between Wi-Fi users, an Ofcom-commissioned study has found.

The report, Estimating the Utilisation of Key Licence-Exempt Spectrum Bands, was carried out by Mass Consultants and published on Wednesday by the telecommunications regulator. The authors recommended a certification scheme for radio devices that use 2.4GHz, claiming this would be in the interests of those promoting such devices.

"Some non-Wi-Fi devices already sport 'Wi-Fi-friendly' claims on their datasheets," the report's authors wrote. "We propose extending this concept to a '2.4GHz-friendly' logo, which would help drive acceptance of innovative technologies in this band."

The 2.4GHz band is licence-exempt, meaning that manufacturers and users do not need to have licences to make or use devices that run in this band. Such devices include not only 802.11b/g Wi-Fi equipment, but also security cameras, remote controls, baby monitors and microwave ovens.

"Where the users' problems are spectrum-related, they tend to be due to interference between devices in the 2.4GHz… band rather than congestion, as was initially believed," the authors wrote. "Such problems are common but geographically dispersed. In the centre of London, however, it has been shown that the demands on this band are much higher than other locations surveyed and users are experiencing the combined effects of interference and congestion."

Ofcom's report noted that many people believed "some domestic users generate excessive amounts of Wi-Fi traffic, denying access to other users".

"Our research suggests that this is not the case, rather the affected parties are almost certainly seeing interference from non-Wi-Fi devices such as microwave ovens, Audio Video (AV) senders, security cameras or baby monitors," the authors wrote.

According to the report, busy inner city locations showed signs of congestions as well as interference, but said even a single device such as an analogue video sender could severely affect Wi-Fi services within a short range in low population density areas.

"These interference problems are the indirect result of light regulation in the 2.4GHz band," the authors wrote. "A plethora of radio types, which are not all designed via standardisation processes, means that peaceful co-existence does not arise organically. Co-existence must be enforced by some means if [licence-exempt] bands are to be shared effectively."

A spokesperson for Ofcom told ZDNet UK on Monday that the regulator was "looking at the results of the report and will consider the options that the report puts forward".