KIMM ANDERSON / AP Enlarge
KIMM ANDERSON / AP Enlarge
ST. CLOUD, Minn. — Flickering ceiling lights are usually a nuisance, but in city offices in St. Cloud, 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 new expressways for short-range communications.
The first few light fixtures built by LVX System, a local start-up, will be installed this week in six municipal buildings in this city of 66,000 in central Minnesota.
The LVX system puts clusters of its light-emitting diodes, or LEDs, in a standard-sized light fixture. The LEDs transmit coded messages — as a series of 1s and 0s in computer speak — to special modems attached to computers.
A light on the modem talks back to the fixture overhead, where there is a sensor to receive the return signal and transmit the data over the Internet. Those computers on the desks aren't connected to the Internet, except through these light signals, much as Wi-Fi allows people to connect wirelessly.
LVX takes its name from the Latin word for light, but the underlying concept is older than Rome; the ancient Greeks signaled each other over long distances using flashes of sunlight off mirrors and polished shields. The Navy has used a Morse-coded version with signal lamps.
The first generation of the LVX system will transmit data at speeds of about 3 megabits per second, roughly as fast as a residential DSL line.
Mohsen Kavehrad, a Penn State electrical engineering professor who has worked 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 Mr. Kavehrad, who is not involved in the LVX project.
But there are significant hurdles. For one, smart phones and computers already work on Wi-Fi networks that are much faster than the LVX system.
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 also will permit lights that can be programmed to change intensity and color.
For the city, the data networking capability is secondary. The main reason it paid a $10,000 installation fee for LVX is to save money on electricity down the line, thanks to the energy-efficient LEDs. Mr. Pederson said, one of his LED fixtures uses about 36 watts of power to provide the same illumination that 100 watts provides with a standard fluorescent fixture.