French start-up Oledcomm demonstrated the Li-Fi technology at the recently held Mobile World Congress, the world’s biggest mobile fair, in Barcelona. Laboratory tests have shown theoretical speeds of over 200 Gbps — fast enough to “download the equivalent of 23 DVDs in one second”. What is Li-Fi? Li-Fi, or light fidelity, invented by German physicist and professor Harald Haas, is a wireless technology that makes use of visible light in place of radio waves to transmit data at terabits per second speeds—more than 100 times the speed of Wi-Fi. How it works? Li-Fi is a Visible Light Communications (VLC) system. This means that it accommodates a photo-detector to receive light signals and a signal processing element to convert the data into ‘stream-able’ content. Unlike Wi-Fi, which uses radio waves, Li-Fi runs on visible light. Here, data is fed into an LED light bulb (with signal processing technology), it then sends data (embedded in its beam) at rapid speeds to the photo-detector (photodiode).
The tiny changes in the rapid dimming of LED bulbs is then converted by the ‘receiver’ into electrical signal. The signal is then converted back into a binary data stream that the user would recognise as web, video and audio applications that run on internet enables devices. An LED lightbulb is a semi-conductor light source meaning that the constant current of electricity supplied to an LED lightbulb can be dipped and dimmed, up and down at extremely high speeds, without being visible to the human eye. Advantages: Li-Fi could make a huge impact on the internet of things too, with data transferred at much higher levels with even more devices able to connect to one another. Li-Fi offers great promise to overcome the existing limitations of Wi-Fi by providing for data-heavy communication in short ranges. Due to its shorter range, Li-Fi is more secure than Wi-Fi. Since it does not pollute, it can be called a green technology for device-to-device communication in the Internet of Things (IoT). Li-Fi systems consume less power. Limitations of Li-Fi: As visual light can’t pass through opaque objects and needs line of sight for communication, its range will remain very restricted to start with. In order to enjoy full connectivity, more capable LED bulbs will need to be placed at various places. Also, initially, there will be high installation costs of visual light communication systems as an add-on to lighting systems.
sources: the hindu.