Via Quartz
-----
Current wireless networks have a problem: The more popular they become, the slower they are. Researchers at Fudan University in Shanghai have just become the latest to demonstrate
a technology that transmits data as light instead of radio waves, which
gets around the congestion issue and could be ten times faster than
traditional Wi-Fi.
In
dense urban areas, the range within which Wi-Fi signals are transmitted
is increasingly crowded with noise—mostly, other Wi-Fi signals. What’s
more, the physics of electromagnetic waves sets an upper limit to the
bandwidth of traditional Wi-Fi. The short version: you can only transmit
so much data at a given frequency. The lower the frequency of the wave,
the less it can transmit.
Li-Fi doesn’t work in the dark or outdoors, but it only has to be a supplement to existing wireless networks to be valuable.AP Photo/Kin Cheung
But
what if you could transmit data using waves of much higher frequencies,
and without needing a spectrum license from your country’s telecoms
regulator? Light, like radio, is an electromagnetic wave, but it has
about 100,000 times the frequency of a Wi-Fi signal, and nobody needs a
license to make a light bulb. All you need is a way to make its
brightness flicker very rapidly and accurately so it can carry a signal.
The idea sounds daft: Who would want to sit under a flickering bulb? But Li-Fi, a standard proposed just two years ago, is seeing rapid technological progress.
First,
data are transmitted to an LED light bulb—it could be the one
illuminating the room in which you’re sitting now. Then the lightbulb is
flicked on and off very quickly, up to billions of times per second.
That flicker is so fast that the human eye cannot perceive it. (For
comparison, the average energy-saving compact fluorescent bulb already flickers between 10,000 and 40,000 times per second.)
Then a receiver on a computer or mobile device—basically, a little
camera that can see visible light—decodes that flickering into data. LED
bulbs can be flicked on and off quickly enough to transmit data around
ten times as fast the fastest Wi-Fi networks. (If they could be
manipulated faster, the bandwidth would be even higher.)
If you’ve ever used a solar-powered calculator, you already know how to connect to Li-Fi.Oledcomm
Li-Fi
has one big drawback compared to Wi-Fi: you, or rather your device,
need to be within sight of the bulb. It wouldn’t necessarily need to be a
special bulb; in principle, overhead lights at work or at home could be
wired to the internet. But it would mean that, unlike with Wi-Fi, you
couldn’t go into the next room unless there were wired bulbs there too.
However, a new generation of ultrafast Wi-Fi devices that we’re likely to start using soon
face a similar limitation. They use a higher range of radio
frequencies, which aren’t as crowded with other signals (at least for
now), and have a higher bandwidth, but, like visible light, cannot
penetrate walls.
Engineers and a handful of startups, like Oledcomm, have been experimenting with Li-Fi technology.
The Fudan University team unveiled an experimental Li-Fi network in
which four PCs were all connected to the same light bulb. Other
researchers are working on transmitting data via different colors of LED
lights—imagine, for example, transmitting different signals through
each of the the red, green and blue LEDs inside a multi-colored LED
light bulb.
Because
of its limitations, Li-Fi won’t do away with other wireless networks.
But it could supplement them in congested areas, and replace them in places where radio signals need to be kept to a minimum, like hospitals, or where they don’t work, such as underwater.