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Li-Fi also li-fi

noun [uncountable]

Light Fidelity: a method of transmitting data wirelessly using LED (= light-emitting diode) technology

'Li-Fi could replace Wi-Fi as university spin-out looks to transmit data through LED light bulbs …'

Global LEDs/OLEDs (press release) 5th March 2012

Imagine only needing to hover under a street lamp to get public internet access, or downloading a movie from the lamp on your desk. There's a new technology on the block which could, quite literally as well as metaphorically, 'throw light on' how to meet the ever-increasing demand for high-speed wireless connectivity. Radio waves are replaced by light waves in a new method of data transmission which is being called Li-Fi.

light-emitting diodes can be switched on and off faster than the human eye can detect, causing the light source to appear to be on continuously

A flickering light can be incredibly annoying, but has turned out to have its upside, being precisely what makes it possible to use light for wireless data transmission. Light-emitting diodes (commonly referred to as LEDs and found in traffic and street lights, car brake lights, remote control units and countless other applications) can be switched on and off faster than the human eye can detect, causing the light source to appear to be on continuously, even though it is in fact 'flickering'. This invisible on-off activity enables a kind of data transmission using binary codes: switching on an LED is a logical '1', switching it off is a logical '0'. Information can therefore be encoded in the light by varying the rate at which the LEDs flicker on and off to give different strings of 1s and 0s. This method of using rapid pulses of light to transmit information wirelessly is technically referred to as Visible Light Communication (VLC), though its potential to compete with conventional WiFi has inspired the popular characterisation Li-Fi.

The concept of Li-Fi is currently attracting a great deal of interest, not least because it may offer a genuine and very efficient alternative to radio-based wireless. As a growing number of people and their many devices access wireless internet, the airwaves are becoming increasingly clogged, making it more and more difficult to get a reliable, high-speed signal. The opportunity to exploit a completely different part of the electromagnetic spectrum is therefore very appealing. As well as being a potential solution to our ever-increasing hunger for bandwidth, Li-Fi has other advantages over WiFi, such as being safe to use on an aircraft, in hospitals and medical devices, and even underwater, where WiFi doesn't work at all.

Research suggests that Li-Fi has the potential to be faster, safer and cheaper than conventional WiFi technology. In more ways than one, it looks like the future of wireless communication definitely has a 'bright side'…

Background – Li-Fi

The technology underpinning Li-Fi was pioneered by German physicist Harald Haas, currently based at the University of Edinburgh in the UK. Haas coined the term Li-Fi in 2011 in the context of a talk presenting the new technology at the TED (Technology Entertainment and Design) Global conference. The word quickly entered common parlance as an instantly recognisable alternative to WiFi. Both terms are examples of abbreviations linguists sometimes describe as clipped forms, i.e. WiFi = wireless fidelity, Li-Fi = light fidelity.

Haas's research project, originally known as D-Light (short for Data Light), is now set to launch a prototype Li-Fi application under the name of newly-formed company VLC (Visible Light Communication) Ltd, which was set up to commercialize the technology.

For teachers


by Kerry Maxwell, author of Brave New Words

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Read last week's BuzzWord. lifelogging.

This article was first published on 8th May 2012.

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