Optical wireless and
broadband over power lines: A high speed
alternativeTuesday, January 10,
2006
University Park, Pa. -- Penn State
engineers have shown that a white-LED system for lighting and
high data-rate indoor wireless communications, coupled with
broadband over either medium- or low-voltage power line grids
(BPL), can offer transmission capacities that exceed DSL or
cable and are more secure than RF.
Colored LEDs or
light emitting diodes currently are found in the numbers on
digital clocks, remote controls, traffic lights and other
applications. Recently, white LEDs have emerged in the market
and the tiny white lights are being considered as replacements
for incandescent and fluorescent bulbs.
Some
researchers predict that by 2012, tiny white LEDs will 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.
Now, Mohsen Kavehrad, the W.L. Weiss
professor of electrical engineering and director of the Center
for Information and Communications Technology Research, and
his team have shown that, in the system they designed,
coupling white LEDs to BPL can deliver secure, wireless bit
rates of a gigabit per second, a rate exceeded only by
fiber.
Kavehrad detailed the Penn State system and its
performance in simulation in a paper, "Hybrid MV-LV Power
Lines and White Light Emitting Diodes for Triple-Play
Broadband Access Communications," at the IEEE Consumer
Communications and Networking Conference in Las Vegas on
Tuesday, Jan. 10. His co-author is Pouyan Amirshahi, a
doctoral candidate in electrical engineering.
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.
Since light does not penetrate walls, as do
the microwaves used in RF, the white LED system is more
secure. In addition, there are no known health hazards
associated with exposure to LED light.
"Optical path
differences can cause signal distortion in high-speed data
transmission," said Kavehrad. "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. For example, in our proposed
system, at worst, distortion limits the data rate to one
gigabit."
Although white LEDs are not yet commercially
available for this type of application, Kavehrad is confident
that they will be. "White LEDs are not there yet but by 2010,
they will be available and economical," he said. "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."
The study was supported through Penn State's
Center for Information and Communications Technology
Research.
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Contact
Barbara
Hale
bah@psu.edu
http://live.psu.edu
814-865-9481
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Contact
Vicki
Fong
vfong@psu.edu
http://live.psu.edu
814-865-9481
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