The term Li-Fi (Light Fidelity) was coined by University of Edinburgh Professor Harald Haas. Harald Haas, coined the term “Li-Fi” at his TED Global Talk where he introduced the idea of “Wireless data from every light”. He is Chairman of Mobile Communications at the University of Edinburgh and co-founder of pureLiFi. Light Fidelity (Li-Fi) is a high-speed and fully networked wireless communication technology. Li-Fi is a form of visible light communication and a subset of optical wireless communications.
Li-Fi and Wi-Fi are quite similar as both transmit data electromagnetically. However, Wi-Fi uses radio waves while Li-Fi runs on visible light. The visible light spectrum is 10,000 times larger than the entire radio frequency spectrum. By August 2013, data rates of over 1.6 Gbit/s were demonstrated over a single color LED in Li-Fi. Researchers have reached data transfer rates of over 224 Gbit/s in Li-Fi. Visible light is only a small portion of the electromagnetic spectrum. Visible light communication (VLC) is a data communications medium which uses visible light between 400 and 800 THz
VLC technology was exhibited in 2012 using Li-Fi. Li-Fi is a Visible Light Communications (VLC) system which is accommodates a photo-detector to receive light signals and a signal processing element to convert the data into ‘stream-able’ content. 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.
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 we would recognize as video, web and audio applications that run on internet enables devices.
There are so many applications work on VLC. But here is some example of it.
1. SMART LIGHTING : Smart lighting with VLC provides the infrastructure for illumination, control and communications and will greatly reduce wiring and energy consumption within a building.
2. WiFi SPECTRUM RELIEF : VLC can provide data rates greatly in excess of current WiFi and this can be done at low cost
3. AVIATION : Radio is undesirable in passenger compartments of aircraft. LEDs are already used for illumination and can also be used instead of wires to provide media services to passengers. This reduces the aircraft construction costs and its weight.
4. UNDERWATER COMMUNICATIONS : RF does not work underwater but visible light can support high speed data transmission over short distances in this environment.
The signal of Li-Fi cannot pass through walls, but Due to its high speeds, Li-Fi could make a huge impact on the internet of things (IOT) too.