UK researchers say
they have achieved data transmission speeds of 10Gbit/s via "li-fi" -
wireless internet connectivity using light.
This means over
10Gbit/s is possible.
Li-fi is an emerging
technology that could see specialised LED lights bulbs providing low-cost
wireless internet connectivity almost everywhere.
High
speed
The research, known as
the ultra-parallel visible light
communications project, is a joint venture between the
universities of Edinburgh, St Andrews, Strathclyde, Oxford, and Cambridge, and
funded by the Engineering and Physical Sciences Research Council.
The tiny micro-LED
bulbs, developed by the University of Strathclyde, Glasgow, allow streams of
light to be beamed in parallel, each multiplying the amount of data that can be
transmitted at any one time.
"If you think of
a shower head separating water out into parallel streams, that's how we can
make light behave," said Prof Harald Haas, an expert in optical wireless
communications at the University of Edinburgh and one of the project leaders.
Using a digital
modulation technique called Orthogonal Frequency Divisional Multiplexing
(OFDM), researchers enabled micro-LED light bulbs to handle millions of changes
in light intensity per second, effectively behaving like an extremely fast
on/off switch.
This allows large
chunks of binary data - a series of ones and zeros - to be transmitted at high
speed.
Earlier this year,
Germany's Fraunhofer Heinrich Hertz Institute claimed that data rates of up to
1Gbit/s per LED light frequency were possible in laboratory conditions.
And this month,
Chinese scientists reportedly developed a microchipped LED bulb that can
produce data speeds of up to 150 megabits per second (Mbps), with one bulb
providing internet connectivity for four computers.
'Light fidelity'
In 2011, Prof Haas demonstrated how an LED bulb equipped with signal
processing technology could stream a high-definition video to a computer.
He
coined the term "light fidelity" or li-fi - also known as visual
light communications (VLC) - and set up a private company, PureVLC, to exploit
the technology.
Li-fi
promises to be cheaper and more energy-efficient than existing wireless radio
systems given the ubiquity of LED bulbs and the fact that lighting
infrastructure is already in place.
Visible
light is part of the electromagnetic spectrum and 10,000 times bigger than the
radio spectrum, affording potentially unlimited capacity.
Another
advantage, Prof Haas argues, is that evenly spaced LED transmitters could
provide much more localised and consistent internet connectivity throughout
buildings.
The
disadvantage of traditional wi-fi routers is that the signal weakens the
further you are away from it, leading to inconsistent connectivity within
offices and homes.
Prof
Haas also believes light's inability to penetrate walls makes VLC technology
potentially more secure than traditional wi-fi connectivity.
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