Lifi's experimental success at Fudan University: Click on the LED light to get online

Visible light communication is called Lifi

All along, painting a shining light bulb on the head of a person is used to symbolize the inspiration of an inventor, but the German physicist Harald Haas "lights up" the light bulb itself. Myth: rely on a small light to turn an invisible network signal into a "visible" network signal. Haas and his team at the University of Edinburgh in the UK have invented a patented technology that uses flashing lights to transmit digital information. This process is called visible light communication (VLC), which is often called "Lifi". In order to show that it can bring revolutionary changes to the wireless network transmission technology currently represented by WiFi.

How far is this unimaginable network technology from us? The answer is: very close, it is coming to us from the Fudan University laboratory step by step. Xue Xiangyang, a professor at the School of Computer Science and Technology of Fudan University, told reporters that the current radio signal transmission equipment has many limitations. They are rare, expensive, but not efficient. For example, mobile phones, millions of base stations around the world help them enhance their signals, but most of them Energy is consumed by cooling, and the efficiency is only 5%. In contrast, the bulbs used in the world are inexhaustible, especially in the domestic LED light source is replacing the traditional incandescent lamps on a large scale. Simply add a microchip to any humble LED bulb to turn the bulb into a wireless network transmitter.

Visible light communication is safe and economical

Since last year, the Shanghai Municipal Science and Technology Commission has deployed this internationally advanced wireless communication technology in universities and research institutes throughout the city. The research and application of key technologies for visible light communication undertaken by Fudan University have made important progress: researchers not only use it in the laboratory environment. The visible light transmits the network signal, and the realization can be "one for four", that is, a small light is illuminated, and four computers can simultaneously access the Internet and transmit network signals at the same time. Professor Chi Nan, a researcher, pointed out that light, like radio waves, is a kind of electromagnetic wave, and the basic principle of transmitting network signals is consistent. In the study, the ordinary LED bulb is equipped with a microchip, which can control it to flash millions of times per second, which means 1 is off and 0 is off. Since the frequency is too fast, the human eye is not aware of it, and the photosensor can receive these changes. In this way, the binary data is quickly encoded into a light signal and transmitted efficiently. The computer under the light, through a set of special receiving devices, read the "Morse password" in the light.

"Where there is a light, there is a network signal. Turn off the lights, the network is completely absent." Chi Nan told reporters that compared with the existing WiFi, the future visible light communication is safe and economical. WiFi relies on invisible radio wave transmission, the power of the device is getting larger and larger, and the local electromagnetic radiation is bound to increase; the wireless signal passes through the wall and the network information is not safe. These security risks are “swept away” in visible light communication. Moreover, the spectrum is 10,000 times larger than the radio spectrum, meaning more bandwidth and higher speeds, and the network setup requires almost no new infrastructure.

Lifi technology also has its limitations

Of course, as a new network technology and products still in the laboratory, its future potential should not be overestimated. "Because, from lighting communication control to chip design and manufacturing, a series of key technology products are all researchers' hands-on, to truly enter the thousands of households like WiFi, through a series of industrial development, there is still very Long way to go." Chi Nan believes that Lifi technology itself has its limitations, for example, if the lights are blocked, the network signal will be cut off and so on. Therefore, it is not a competitor to WiFi, but a complement to each other that helps to free up spectrum space. In the future, whether it can produce killer-style applications, but also rely on people's unlimited imagination: cars rely on LED lights to "dialogue", passengers in the aircraft cabin use the overhead LED reading lights to go online...