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TEDGlobal>London

Harald Haas: Forget Wi-Fi. Meet the new Li-Fi Internet

September 29, 2015

What if we could use existing technologies to provide Internet access to the more than 4 billion people living in places where the infrastructure can't support it? Using off-the-shelf LEDs and solar cells, Harald Haas and his team have pioneered a new technology that transmits data using light, and it may just be the key to bridging the digital divide. Take a look at what the future of the Internet could look like.

Harald Haas - Communications technology innovator
Harald Haas is the pioneer behind a new technology that can communicate as well as illuminate. Full bio

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Double-click the English subtitles below to play the video.
I would like to demonstrate
for the first time in public
00:12
that it is possible to transmit a video
00:15
from a standard off-the-shelf LED lamp
00:19
to a solar cell with a laptop
acting as a receiver.
00:24
There is no Wi-Fi involved,
it's just light.
00:30
And you may wonder, what's the point?
00:32
And the point is this:
00:35
There will be a massive
extension of the Internet
00:38
to close the digital divide,
00:40
and also to allow for what we call
"The Internet of Things" --
00:43
tens of billions of devices
connected to the Internet.
00:47
In my view, such an extension
of the Internet can only work
00:51
if it's almost energy-neutral.
00:55
This means we need to use existing
infrastructure as much as possible.
00:57
And this is where the solar cell
and the LED come in.
01:03
I demonstrated for the first time,
01:08
at TED in 2011,
01:11
Li-Fi, or Light Fidelity.
01:13
Li-Fi uses off-the-shelf LEDs
to transmit data incredibly fast,
01:15
and also in a safe and secure manner.
01:21
Data is transported by the light,
01:25
encoded in subtle changes
of the brightness.
01:28
If we look around,
we have many LEDs around us,
01:32
so there's a rich infrastructure
of Li-Fi transmitters around us.
01:35
But so far, we have been using
special devices -- small photo detectors,
01:41
to receive the information
encoded in the data.
01:46
I wanted to find a way to also use
existing infrastructure
01:50
to receive data from our Li-Fi lights.
01:54
And this is why I have been looking into
solar cells and solar panels.
01:58
A solar cell absorbs light
and converts it into electrical energy.
02:02
This is why we can use a solar cell
to charge our mobile phone.
02:08
But now we need to remember
02:13
that the data is encoded in subtle changes
of the brightness of the LED,
02:14
so if the incoming light fluctuates,
02:21
so does the energy harvested
from the solar cell.
02:24
This means we have
a principal mechanism in place
02:28
to receive information from the light
and by the solar cell,
02:31
because the fluctuations
of the energy harvested
02:38
correspond to the data transmitted.
02:40
Of course the question is:
02:43
can we receive very fast and subtle
changes of the brightness,
02:45
such as the ones transmitted
by our LED lights?
02:50
And the answer to that is yes, we can.
02:54
We have shown in the lab
02:58
that we can receive up to 50
megabytes per second
03:00
from a standard, off-the-shelf solar cell.
03:03
And this is faster than most
broadband connections these days.
03:06
Now let me show you in practice.
03:11
In this box is a standard,
off-the-shelf LED lamp.
03:16
This is a standard,
off-the-shelf solar cell;
03:23
it is connected to the laptop.
03:25
And also we have an instrument here
03:28
to visualize the energy
we harvest from the solar cell.
03:31
And this instrument shows
something at the moment.
03:34
This is because the solar cell already
harvests light from the ambient light.
03:37
Now what I would like to do first
is switch on the light,
03:42
and I'll simply, only switch on the light,
03:45
for a moment,
03:47
and what you'll notice is that
the instrument jumps to the right.
03:50
So the solar cell, for a moment,
03:54
is harvesting energy
from this artificial light source.
03:56
If I turn it off, we see it drops.
04:00
I turn it on ...
04:03
So we harvest energy with the solar cell.
04:04
But next I would like to activate
the streaming of the video.
04:08
And I've done this
by pressing this button.
04:15
So now this LED lamp here
is streaming a video
04:17
by changing the brightness of the LED
in a very subtle way,
04:22
and in a way that you can't
recognize with your eye,
04:26
because the changes
are too fast to recognize.
04:29
But in order to prove the point,
04:33
I can block the light of the solar cell.
04:35
So first you notice
the energy harvesting drops
04:39
and the video stops as well.
04:43
If I remove the blockage,
the video will restart.
04:44
(Applause)
04:49
And I can repeat that.
04:55
So we stop the transmission of the video
and energy harvesting stops as well.
04:57
So that is to show that the solar cell
acts as a receiver.
05:03
But now imagine that this LED lamp
is a street light, and there's fog.
05:07
And so I want to simulate fog,
05:13
and that's why I brought
a handkerchief with me.
05:16
(Laughter)
05:19
And let me put the handkerchief
over the solar cell.
05:20
First you notice
05:25
the energy harvested drops, as expected,
05:27
but now the video still continues.
05:31
This means, despite the blockage,
05:34
there's sufficient light coming through
the handkerchief to the solar cell,
05:37
so that the solar cell is able to decode
and stream that information,
05:41
in this case, a high-definition video.
05:46
What's really important here is that
a solar cell has become a receiver
05:50
for high-speed wireless signals
encoded in light,
05:56
while it maintains its primary function
as an energy-harvesting device.
06:00
That's why it is possible
06:05
to use existing solar cells
on the roof of a hut
06:08
to act as a broadband receiver
06:12
from a laser station on a close by hill,
or indeed, lamp post.
06:14
And It really doesn't matter
where the beam hits the solar cell.
06:19
And the same is true
06:23
for translucent solar cells
integrated into windows,
06:24
solar cells integrated
into street furniture,
06:28
or indeed, solar cells integrated
into these billions of devices
06:32
that will form the Internet of Things.
06:36
Because simply,
06:38
we don't want to charge
these devices regularly,
06:39
or worse, replace the batteries
every few months.
06:42
As I said to you,
06:46
this is the first time
I've shown this in public.
06:47
It's very much a lab demonstration,
06:50
a prototype.
06:52
But my team and I are confident
that we can take this to market
06:54
within the next two to three years.
06:57
And we hope we will be able to contribute
to closing the digital divide,
07:00
and also contribute
07:05
to connecting all these billions
of devices to the Internet.
07:06
And all of this without causing
07:10
a massive explosion
of energy consumption --
07:11
because of the solar cells,
quite the opposite.
07:14
Thank you.
07:16
(Applause)
07:17

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Harald Haas - Communications technology innovator
Harald Haas is the pioneer behind a new technology that can communicate as well as illuminate.

Why you should listen

Imagine using your car headlights to transmit data ... or surfing the web safely on a plane, tethered only by a line of sight. Harald Haas is working on it. He currently holds the Chair of Mobile Communications at the University of Edinburgh, and is co-founder and Chief Scientific Officer of pureLiFi Ltd as well as the Director of the LiFi Research and Development Center at the University of Edinburgh. His main research interests are in optical wireless communications, hybrid optical wireless and RF communications, spatial modulation, and interference coordination in wireless networks.

Haas has long been studying ways to communicate electronic data signals, designing modulation techniques that pack more data onto existing networks. But his latest work leaps beyond wires and radio waves to transmit data via an LED bulb that glows and darkens faster than the human eye can see. His group published the first proof-of-concept results demonstrating that it is possible to to turn commercially available light emitting diode (LED) light bulbs into broadband wireless transmission systems. 

"It should be so cheap that it's everywhere," he says. "Using the visible light spectrum, which comes for free, you can piggy-back existing wireless services on the back of lighting equipment."

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