Communications of the ACM
Tripping the Light Fantastic
Credit: Yahoo! Taiwan
Casio recently unveiled a prototype for a smartphone that can transmit data using light. The phone's screen flickers with varying intensity to transmit data to another device. The flickering is so slight that it is imperceptible to the human eye, but the camera on another phone can sense it at a distance of up to 10 meters. The technology is the basis for a fast and inexpensive wireless-communication system known as Li-Fi.
To turn a light into a Li-Fi router involves changing its output to carry a message, and linking it with a network cable to a modem that is connected to a telephone or cable-broadband service. The University of Edinburgh's Gordon Povey notes that Li-Fi takes advantage of light-emitting diodes (LEDs), which are more efficient than incandescent bulbs and fluorescent tubes. The Edinburgh researchers have transferred 130 megabits of data per second over about two meters using LEDs.
Povey says that adapting existing LEDs to work with the sensors and light sources already found in smartphones and other devices will be the fastest way to bring Li-Fi to market. He notes that as light bulbs are gradually replaced by LEDs, every home, office, and public building could become a Li-Fi hotspot.
From The Economist
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