Flickering lights could be used to help offices send internet data to computers

Flickering ceiling lights are usually a nuisance, but in city offices in St Cloud, Minnesota, they will actually be a pathway to the internet.

The lights will transmit data to specially equipped computers on desks below by flickering faster than the eye can see.

Ultimately, the technique could ease wireless congestion by opening up new expressways for short-range communications.

The LVX system puts clusters of its light-emitting diodes, or LEDs, in a standard-sized light fixture. The LEDs transmit coded messages to special modems attached to computers.

A light on the modem talks back to the fixture overhead, where there is sensor to receive the return signal and transmit the data over the internet. The first generation of the LVX system will transmit data at speeds of about three megabits per second, roughly as fast as a residential DSL line.

Mohsen Kavehrad, a Penn State electrical engineering professor who has been working with optical network technology for about 10 years, said the approach could be a vital complement to the existing wireless system.

He said the radio spectrum usually used for short-range transmissions, such as Wi-Fi, is getting increasingly crowded, which can lead to slower connections.

"Light can be the way out of this mess," said Kavehrad, who is not involved in the LVX project.

Technology analyst Craig Mathias of the Farpoint Group said the problems with wireless congestion will ease as Wi-Fi evolves, leaving LVX's light system to niche applications such as indoor advertising displays and energy management.

LVX Chief Executive Officer John Pederson said a second-generation system that will roll out in about a year will permit speeds on par with commercial Wi-Fi networks. It will also permit lights that can be programmed to change intensity and colour.

PA