Li-Fi: how the LED light turns into a modem

Scientists have been experimenting with new data transmission technology through LEDs in fluorescent lamps for several years. When paired with a photo receiver, the lamp turns into a normal modem. By analogy with Wi-Fi, this type of connection is called Li-Fi. If the LEDs flicker with high frequency in different colors, then you can achieve a fairly high data transfer rate. For example, two years ago the Germans recorded a speed of 800 Mbit / s at a distance of 1.8 meters in the laboratory. However, until the practical implementation of the case they have not yet reached.

But engineers from Fudan University in Shanghai recently conducted an experiment with Li-Fi , where four personal computers went online through one 1-watt LED light bulb.

According to the authors of the study, a light bulb with a microcircuit provides data transfer rates of up to 150 Mbps. The technology is ready for use: on November 5, the China International Industry Fair exhibition is promised to bring ten sets of Li-Fi samples.

Although this transmission method, by definition, works only in the direct line of sight, it is theoretically possible to combine all the lamps in an apartment into a mesh network through which a signal can be transmitted, for example, from one room to another through a common corridor. Lamps flicker at a high frequency, this should not be noticeable to the eye. For comparison, a standard fluorescent lamp flickers at a frequency of 10 to 40 kHz. That is, the person will feel that the lamp is shining as usual.
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Engineers believe that using light as a carrier has advantages over radio waves. First, the benefit in energy consumption: in radio modems, the efficiency does not exceed 5%, most of the energy goes into heat. Secondly, theoretically light can transmit information at a much higher speed than by radio, simply due to a shorter wavelength. Third, light bulbs can be used in hospitals, and in a densely populated city hotspots will not interfere with each other, like WiFi.