Li-fi: 100 times faster than wi-fi

Harald Haas invented li-fi in 2011.

Harald Haas invented li-fi in 2011.

Harald Haas, a professor at Edinburgh University is a busy man.  In 2011 he invented a wireless broadband technology that uses LEDs to send data at hundreds of times the speed of today's wi-fi networks.

The system is known as li-fi (short for light fidelity) and offers compelling advantages over wi-fi. 

Not only is it is more energy efficient, but it is also capable of up to 10,000 times the bandwidth of wi-fi. Many see li-fi as being complimentary to wi-fi.

Wi-fi uses unlicensed 2.4 GHz or 5 GHz radio spectrum. Li-fi uses visible light between 400 and 800 terahertz. As the number of wi-fi devices proliferates, overcrowding could render wi-fi unusable. Li-fi could help ease this congestion.

Transmitting data using light isn't anything new. Back in 1880, Alexander Graham Bell (the inventor of the telephone) transmitted audio using visible light.

What is new with li-fi is the use of specialised LED driver chips. These can dim and brighten LEDs encoding data much like a fast form of Morse code. The entire process happens so fast that it is completely imperceptible to humans.

At its simplest, a li-fi system consists of an LED transmitter and solar panel receiver system. It might sound basic, but it works, and it is fast. In the lab, li-fi has clocked in at speeds of up to 224 gigabits per second. Back in the real world, data speeds from a single 5Mw micro LED are around a still zippy 1-3 gigabit per second.

It's also secure. wi-fi signals can penetrate most walls to pass beyond the boundary of your home or business and can be intercepted. Light doesn't penetrate walls so securing a li-fi network can be as simple as drawing the blinds.

You'd be forgiven for thinking that staying online with li-fi would need the lights left on. Haas's li-fi system is so sensitive that he's demonstrated it working with LED bulbs dimmed to such low levels that they appear turned off.

Commercial interest is mounting. Velmenni, an Estonian company, has already developed a commercial version of the technology. They've already trialled it in offices and industrial environments in Estonia. The Velmenni version of li-fi has recorded speeds of up to 1GBps.  

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This is up to 100-times faster than the current crop of wi-fi technologies.

Haas' own company, PureLiFi, is also manufacturing li-fi equipment for businesses. Although home li-fi is still several years away, adoption of much of the infrastructure needed (LED lighting) continues to grow, which could make retrofitting li-fi a hassle-free process.

The potential for li-fi could is significant. One of the most obvious is using li-fi to deliver broadband using LED streetlights. Li-fi does have its limitations. Performance varies with lighting conditions. For outdoor use weather such as fog or rain could impact data throughput.

 - Stuff


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