TECHNOLOGY FOR CHANGE

Let There Be Broadband: Light Fixtures of Tomorrow Will Handle Data

Stan Gibson | Date: 03-22-10 | Comments

The use of light waves could be a convenient high-speed alternative to present-day WiFi networks.

Researchers in Germany have set a new speed record in the race to send data across light waves. The breakthrough heralds the day when domestic light fixtures will double as broadband transmitters.

�The advantage is that you'd be using light that is already there,� says Dr. Jelena Vučić, a scientist at the Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institute, in Germany. The use of light waves could be a convenient high-speed alternative to present-day WiFi networks. Work to hammer out a standard in this field is being carried out by the IEEE 802.15.7 task group.

The lights used are not the common incandescent and fluorescent bulbs of today, but LED fixtures that are widely expected to become prevalent in the future. Data is transmitted by modulating or flickering the blue spectrum of the light very quickly�so fast that it�s invisible to the eye.

�You can still use the light to read. You still see white light because we�re only modulating the blue part of the light for data,� Vučić explains.

Vučić and her team sent data from a server to an LED ceiling light that delivered three high-definition video streams to receivers attached to laptops. The group began with a download rate of 100M bps and bumped that up to 230M bps, setting the speed record. Vučić says that rate could be doubled again by the use of a more sophisticated modulation signal.

Light waves can�t pass through walls as do radio waves. �If you place your hand on the receiver, the video freezes; if you remove it, the video goes on,� says Vučić. Practical future implementations would rely on multiple light sources in a given room to avoid the problem of a piece of furniture or a person�s body blocking the signal. However, that same characteristic can help confine a local area network to a building to deter hackers and keep out interference from neighboring networks.

Vučić and her colleagues will be presenting their findings during the Optical Fiber Communication Conference and Exposition/National Fiber Optic Engineers Conference (OFC/NFOEC), which will take place March 21-25 in San Diego.

Once the IEEE agrees on a standard, possibly this year, commercial products might be available two to three years after that, states Vučić.