01.17.2006 12:00 AM
Penn State Engineers Combine White LEDs and BPL for High-speed Indoor Wireless
Mohsen Kavehrad, the W.L. Weiss professor of electrical engineering and director of the Center for Information and Communications Technology Research at Penn State, working with other engineers there have designed a system that couples white LEDs to broadband over power line data, allowing wireless transmission at bit-rates of a gigabit per second.
The Penn State news release Optical wireless and broadband over power lines: A high-speed alternative
, said that in the system, white LEDs are positioned so the room is lit uniformly. The LEDs are plugged into the room's electrical system. Broadband data on the power line modulates the white LED lights in the room. An optical wireless receiving device illuminated by the modulated light decodes the data.
As long as the light stays in the room, the data from the LEDs is secure. Of course, if the data exists as RF on the power line, it can it can easily be intercepted with some BPL systems.
While the concept sounds simple, there are complications. Professor Kavehrad said, "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. For example, in our proposed system, at worst, distortion limits the data rate to one gigabit."
Kavehrad admitted that white LEDs are not commercially available for this type of application, but he saw this changing. "White LEDs are not there yet but by 2010, they will be available and economical. In the future, when you turn on the lights for indoor low-cost lighting, you could receive broadband via the same white-light LED."