The benefits of light-emitting diodes (LEDs) as a brighter, more efficient alternative to fluorescent lamps have become common knowledge. It may only be a matter of time before LEDs become the lighting source of choice for consumers.
What is not so widely known is another beneficial use of LEDs—as a wireless network router.
Light bulbs that produce their own wireless digital signal—light fidelity, or Li-Fi—are the subject of research around the world. While the technology has not reached the same degree of mainstream usability as its lighting counterpart, scientists have made notable gains this year.
In April, Germany’s Fraunhofer Heinrich Hertz Institute claimed that data could be transmitted by standard off-the-shelf LEDs at a rate of 1 gigabit per second (Gbps) per light frequency. Since LEDs typically use three frequencies, one for each of the three primary colors—red, green and blue—that make up white light, the Institute claimed the total speed could reach 3 Gbps.
In October, scientists at Shanghai’s Fudan University announced that they had developed a microchipped LED bulb that can produce data speeds up to 150 megabits per second with one bulb providing Internet connectivity for four computers.
Shortly after that announcement, a group of researchers in the United Kingdom announced its own breakthrough. They developed a micro-LED light bulb that can transmit 3.5 Gbps per each of the three bands of color, reaching a total speed of 10 Gbps.
Their research—a joint venture between the universities of Edinburgh, St. Andrews, Strathclyde, Oxford and Cambridge—described as the ultra-parallel visible light communications project, referring to the three streams of light beamed in parallel to maximize the amount of data transmitted. They use a process known as orthogonal frequency divisional multiplexing, which produces millions of changes in light intensity per second to generate binary, or digital, signals.
Use of LEDs as a source of data transmission has many advantages, including cost and security. Since the signal is limited to line of sight, it has disadvantages compared with traditional Wi-Fi, which is transmitted over radio signals and can penetrate walls. As LEDs become more widely used, the Li-Fi application could become a popular and affordable means of hooking up to a network or the Internet.