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 10 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.
10x Faster Connections Than Wi-Fi, Through the Nearest Lamp
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?
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 10 times as fast as the fastest Wi-Fi networks. (If they could be
manipulated faster, the bandwidth would be even higher.)
Li-Fi’s Limitations Are Similar to Next-Generation Wi-Fi
Li-Fi has one big drawback compared with 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 ultra-fast 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.
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