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Researchers Envision an LED-Powered Wireless Network
January 25, 2006

Could a new LED someday power a WiFi-type network supporting bit rates of up to 1 gigabit per second? Penn State University researchers think so, predicting that such a system, coupled with broadband over either medium- or low-voltage power line (BPL) grids, could potentially offer transmission capacities that exceed today's DSL and cable technologies while providing more security than existing RF-based wireless networks.


The technology's key, the researchers say, are white LEDs. They note that by 2012 tiny white LEDs could deliver light brighter than a 60 watt-bulb, yet draw only as much current as provided by four D-size batteries. A Japanese team recently suggested using white LEDs not only for lighting but also as light sources for wireless in-house communications.


A team assembled by Mohsen Kavehrad, a Penn State professor of electrical engineering and director of the university's Center for Information and Communications Technology Research, has designed an experimental system that shows that coupling white LEDs to BPL can deliver secure, wireless bit rates of 1G bps. That's a data rate currently only exceeded by fiber networks.


In the Penn State system, white LEDs are positioned so that the room is lit as uniformly as possible. Since the LEDs are plugged into the room's electrical system, broadband data, voice or video delivered via the power lines can piggyback on the light that fills the room to reach any wireless receiving devices present.


The technique also promises enhanced wireless security. Since light doesn't penetrate walls, as do the microwaves used in RF-based system, the white LED approach is potentially more secure. Additionally, there are no known health hazards associated with exposure to LED light.


While the LED wireless technology seems to present numerous benefits, there are also some roadblocks that could potentially block widespread deployment. Kavehrad notes that optical path differences can cause signal distortion in high-speed data transmission. This distortion is highly dependent on the room's dimensions and system configuration. However, if a system is designed appropriately, this distortion can be minimized, he claims. "For example, in our proposed system, at worst, distortion limits the data rate to one gigabit," says Kavehrad.


Although white LEDs are not yet commercially available for wireless applications, Kavehrad is confident that they eventually will be. "White LEDs are not there yet, but by 2010 they will be available and economical," he predicts. "Their low-energy consumption will make them especially attractive. In the future, when you turn on the lights for indoor low-cost lighting, you could receive broadband via the same white light LED.


Copyright 2004 PricewaterhouseCoopers. PricewaterhouseCoopers refers to the network of member firms of PricewaterhouseCoopers International Limited, each of which is a separate and independent legal entity. All rights reserved. The preceding article was written by John Edwards, a freelance technology writer based in Gilbert, Arizona. He can be reached by phone at +1-480-854-0011.

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