Li-Fi

Li-Fi, which stands for Light Fidelity, is a Visible Light Communications (VLC) system, which transmits data between devices by using light waves emitted by Light Emitting Diodes, or LEDs. The term was coined by Harold Has, a professor at the University of Edinburgh, during a Ted-Talk in 2011. In Li-Fi, the LED is the equivalent of a router, and data transfer is capable of reaching speeds of 224 gigabytes per second, and is, on an average, 100 times faster than Wi-Fi. While 224 GB/s was tested under lab conditions, speeds will be a lot slower in real-world applications, although they are predicted to outshine Wi-Fi even then. Li-Fi is currently only in its testing phase, with commercialisation predicted in a few years. Li-Fi is currently being marketed and developed mainly by a company called *pureLiFi*, which introduced the first Li-Fi dongle.

Professor Harold Haas coined the term Li-Fi in 2011, during a TED Global Talk in Edinburgh, where he introduced the idea of ‘wireless data from every light’. He demonstrated the use of Li-Fi by streaming a video onto a laptop, with the use of an LED light and a solar panel. The transfer of data which Professor Haas demonstrated was only a single direction one, unlike that required for browsing the Internet. Haas went on to found a company called *pureLiFi* in 2012, which is now a pioneer in LiFi technology, and has released products to the public which enable LiFi. These are not in common use yet, but the commercial value for LiFi is expected to increase greatly in the future. *PureLiFi* partnered up with a French lighting company called Lucibel, to create a Li-Fi integrated light system for households.

Data is transmitted over Li-Fi by the use of LED light bulbs, which can be dimmed and brightened at extremely high speeds, due to the fact that they are a semiconductor light source. These changes are not visible to the human eye, so that it is not intrusive. These light bulbs must be fitted with a signal processing technology, which streams data from servers and the Internet and transmits it through the beam of the light bulb. Then, a receiver dongle captures the beams by using a photodiode and converts the changes in amplitude into electrical signals. These electrical signals are then converted back in binary form, which is then recognised as web, video, and audio applications.