Visible light communication Lifi: No need for WiFi, you can surf the Internet by turning on LED lights

No WiFi signal is needed, just turn on an LED light to surf the Internet. Recently, the School of Computer Science and Technology of Fudan University has announced that an international cutting-edge communication technology that uses visible light in the room to transmit network signals has been successfully implemented in the laboratory. Researchers connected the network signal to a 1W LED lamp bead, and 4 computers under the light can surf the Internet, with a maximum speed of 3.25G and an average Internet speed of 150M, which is the fastest "Internet access by light" in the world. Next month, 10 prototypes will be unveiled at the 2013 Shanghai Industrial Expo.

　　Visible light communication is called Lifi

　　Drawing a flashing light bulb above a person's head has long been used to symbolize an inventor's sudden inspiration, but German physicist Harald Haas has come up with a brilliant idea: relying on a small light to turn invisible network signals into "visible" network signals. Haas and his team at the University of Edinburgh in the UK have recently invented a patented technology that uses flashing lights to transmit digital information. This process is called visible light communication (VLC), and people often affectionately call it "Lifi" to show that it can bring revolutionary changes to the current wireless network transmission technology represented by WiFi.

　　How far is this unimaginable network technology from us? The answer is: very close, it is coming to us step by step from the laboratory of Fudan University. Xue Xiangyang, a professor at the School of Computer Science and Technology of Fudan University, told reporters that there are many limitations in the current radio signal transmission equipment. They are rare, expensive, but inefficient. For example, mobile phones have millions of base stations around the world to help them enhance signals, but most of the energy is consumed in cooling, with an efficiency of only 5%. In contrast, light bulbs used all over the world are inexhaustible, especially in China, where LED light sources are replacing traditional incandescent lamps on a large scale. Just add a microchip to any humble LED bulb to turn it into a wireless network transmitter.

　　Visible light communication is safe and economical

　　Since last year, the Shanghai Science and Technology Commission has deployed this international cutting-edge wireless communication technology in universities and research institutes across the city. The research and application of key technologies of visible light communication undertaken by Fudan University has made important progress: researchers not only use visible light to transmit network signals in a laboratory environment, but also achieve "one to four", that is, by lighting a small light, four computers can access the Internet and transmit network signals to each other at the same time. Professor Chi Nan, a researcher on the project, pointed out that light, like radio waves, is a type of electromagnetic wave, and the basic principle of propagating network signals is the same. In the study, ordinary LED bulbs were equipped with microchips, which can be controlled to flash millions of times per second. When it is on, it means 1, and when it is off, it means 0. Because the frequency is too fast, the human eye cannot perceive it at all, but the photosensitive sensor can receive these changes. In this way, binary data is quickly encoded into light signals and effectively transmitted. The computer under the light can read the "Morse code" in the light through a special receiving device.

　　"Where there is light, there is network signal. Turn off the light and there is no network at all." Chi Nan told reporters that compared with existing WiFi, future visible light communication is safe and economical. WiFi relies on invisible radio wave transmission. As the power of equipment increases, local electromagnetic radiation is bound to increase. Wireless signals pass through walls, and 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, which means greater bandwidth and higher speed, and network settings require almost no new infrastructure.

　　Lifi technology also has its limitations

　　Of course, as a brand-new network technology and product still in the laboratory, its future potential should not be overestimated. "Because, a series of key technology products, from lighting communication control to chip design and manufacturing, are all 'hands-on' by researchers. To really enter thousands of households like WiFi, it needs to go through a series of industrial developments, and there is still a long way to go." Chi Nan believes that Lifi technology itself also has its limitations. For example, if the light is blocked, the network signal will be cut off, etc. Therefore, it is not a competitor of WiFi, but a mutual complement that helps to free up spectrum space. Whether it can produce killer applications in the future depends on people's unlimited imagination: cars rely on LED lights to "talk" to each other, and passengers in the cabin of an airplane use the LED reading lights above their heads to surf the Internet...