You may soon be able to go online with a flick of your light switch
What is it?
A way of transmitting data using the light emitted from LED lightbulbs. Supporters of the technology say it has several key qualities that will make it a viable alternative to Wi-Fi.
What are they?
First, it’s much faster. UK researchers say they’ve hit 10Gbps. Second, unlike Wi-Fi, you can use multiple Li-Fi devices in a room without them interfering with each other. Third, Wi-Fi is more expensive to run, and requires huge resources of energy to cool the base stations connected to masts. Li-Fi can also be used in places where Wi-Fi is a security risk, such as aircraft cabins, hospitals and nuclear power plants.
But its biggest advantage is that the Li-Fi spectrum, comprising visible light, is 10,000 times wider than Wi-Fi’s, which uses radio and microwaves.
Why is that important?
Because we’re heading for Wi-Fi gridlock. By 2019, experts predict that more than 10 billion devices will need Wi-Fi, and there isn’t enough spectrum to cope with that kind of overload. Li-Fi could boost capacity so we can all continue using the devices we now take for granted.
Can I use my existing lightbulbs?
Afraid not. Li-Fi works only with bulbs that have a special chip inside. This varies the intensity of the light in order to convert it into binary data (zeros and ones), which is picked up by a light sensor on the web-enabled device.
Won’t that give me a headache?
No, because the changes in brightness are imperceptible to the human eye, so there’s no annoying flicker. You do need to keep the lightbulbs switched on, but they can be dimmed so they are barely visible.
Is anyone using Li-Fi yet?
Yes. Nasa is planning to see how well the technology works on board the International Space Station. It’s been suggested that Li-Fi could be used on future manned trips to Mars.
Commercial enterprises are also experimenting with the technology, aware there’s big money to be made. Disney, for example, is working on a ‘Linux Light Bulb’ that lets toys ‘talk’ to each other. One of the leading manufacturers is the Edinburgh-based firm PureLifi (http://purelifi.com), which produced the above illustration to show how the technology works. It may look like the man with the tablet is stepping into a room full of showers, but those are shafts of light, each transmitting data.
If it’s so good, why aren’t we all using it?
Because it’s only recently been shown to work. Step forward Harald Haas, a professor at Edinburgh University and co-founder of PureLifi, who first demonstrated it at a conference in 2011 (watch his speech and read the transcript at www.snipca.com/18269). Haas even coined the term Li-Fi, saying it stands for ‘Light Fidelity’.
Haas imagines a world where cars use Li-Fi to prevent accidents and every street light provides internet access. He thinks that by 2040 Li-Fi “will serve thousands of applications and will be an integral part of the emerging smart cities, smart homes and the internet of things”.
Does it have any drawbacks?
Yes, the biggest being that it can’t penetrate walls. But that wouldn’t be a problem if every room in your house had a Li-Fi-powered lightbulb.
How long has it been around?
Longer than you may think. It’s a form of optical wireless communication, in which light is used to carry a signal. Nasa says this phenomenon was first detected by Alexander Graham Bell in the 1880s. He transmitted speech using changes in sunlight over a distance of several hundred yards. This led to his photophone (Wikipedia page: www.snipca.com/18279), which used the same principles as fibre-optic internet did over 100 years later. Clever chap, that Mr Bell.