UK Researchers Build Micron LED Light Based Wireless Network

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UK Researchers Build Micron LED Light Based Wireless Network

Posted by timothy on Thursday January 31, 2013 @04:19AM from the stay-in-sight-of-the-tower dept.

Mark.JUK writes "Scientists working at the University of Strathclyde in Scotland (United Kingdom) have begun to develop a new Light Fidelity (Li-Fi) technology that will use special micron-sized LED (Light-Emitting Diodes) lights, such as those that could be used as part of home lighting or TV displays, to form part of a sophisticated wireless communications network (much like Wi-Fi is today). The principle, which revolves around manipulating the on/off flicker of LED lights to produce a digital network (a bit like Morse Code from a torch), is not new but most of the other teams are focusing on larger Li-Fi LEDs of around 1mm square in size. However micron sized LEDs not only allow you to use more lights (each of which can act as a separate data channel) but they can also flicker on and off around 1,000 times quicker than the larger LEDs."

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Transmitting binary data using a flashing light by slim · 2013-01-31 04:22 · Score: 5, Funny

(a bit like Morse Code from a torch)
Thanks for the clarification, News for Nerds.
1. Re:Transmitting binary data using a flashing light by OzPeter · 2013-01-31 04:35 · Score: 1
  
  (a bit like Morse Code from a torch)
  Thanks for the clarification, News for Nerds.
  Unfortunately that description is in TFA
  
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2. Re:Transmitting binary data using a flashing light by wonkey_monkey · 2013-01-31 05:08 · Score: 1
  
  If only there was some alternative to blindly copying and pasting a few paragraphs from the article when crafting a Slashdot summary...
  
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3. Re:Transmitting binary data using a flashing light by NatasRevol · 2013-01-31 06:10 · Score: 1
  
  Yay us!
  
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4. Re:Transmitting binary data using a flashing light by LocutusMIT · 2013-01-31 08:09 · Score: 1
  
  Like Fry! Like Fry!
Wavelength by i+kan+reed · 2013-01-31 04:28 · Score: 1

What kind of frequencies are these things capable of? If it's less than a couple hundred megahertz, good luck using that for anything on the other side of a wall.
1. Re:Wavelength by Anonymous Coward · 2013-01-31 04:56 · Score: 1
  
  It is light we're talking about here, so the carrier is in the TeraHertz range, and the data frequency could be up to the Gigahertz. I'm not sure where you're confused. This won't make it through walls like Wi-Fi, but it sure will make it across an empty room.
  I've heard of this kind of thing before, and part of the advantage is in security - you neighbor on the other side of the wall won't be able ton intercept.
2. Re:Wavelength by hardie · 2013-01-31 04:58 · Score: 1
  
  i kan reed is correct. The issue is not some theoretical one involving the frequency of light. The question is "how fast can you modulate an LED"?
3. Re:Wavelength by suutar · 2013-01-31 05:01 · Score: 1
  
  It's visible light, so yeah, no penetration. TFA says it won't replace your wifi if you're looking for multi-room coverage. On the other hand, it keeps your neighbors from using (or sniffing) your net, so maybe it's a feature. (TFA also characterizes it as being useful for "broadcasting" information; use these in roadsign displays and they can shovel data on road conditions to your GPS if it has line of sight, but the earlier work it's based on did work for using the room light as a single-room WAP.)
4. Re:Wavelength by stewsters · 2013-01-31 05:09 · Score: 1
  
  It doesn't stop them from sniffing if you have windows. You could still aim a very sensitive camera at the room. It does make it harder and much more expensive through.
5. Re:Wavelength by citizenr · 2013-01-31 05:33 · Score: 1
  
  it sure will make it across an empty room.
  Highly doubtful, unless you invent some superfast gigapixel cameras as receivers.
  This thing will work up to tens of centimeters like IrDA
  
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6. Re:Wavelength by dave420 · 2013-01-31 05:42 · Score: 1
  
  The receiver doesn't have to know from where the signal originates, so a simple detector of the used wavelength would suffice.
7. Re:Wavelength by TheGratefulNet · 2013-01-31 06:29 · Score: 1
  
  its not just the led, its the pair of led and phototransistor.
  I recently tried some opto couplers (for isolation in circuits) and found that some lower grade parts work at the microsecond level but the better parts are in nanoseconds. it meant the diff of being limited at 57k via several mhz.
  then again, that's inside a chip with a good path between tx and rx.
  in a room, you have varying distances, reflections, obstructions.
  this is going to be hard to 'get right'. I would not bet too strongly on this. rf still rules.
  
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8. Re:Wavelength by DarwinSurvivor · 2013-02-02 07:21 · Score: 1
  
  Funny, my remote control (same technology, slower data) works from tens of METERS away.
I have a better name for that... by Zaatxe · 2013-01-31 04:29 · Score: 3, Funny

If this system sends data with light, but through the air, I would call it "fiberless".

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1. Re:I have a better name for that... by Beorytis · 2013-01-31 05:40 · Score: 1
  
  Correspondingly the best name for this would be "FLAN" ("Fiberless LAN").
  So early adopters will be Mexican restaurants?
2. Re:I have a better name for that... by DroolTwist · 2013-01-31 06:45 · Score: 1
  
  Will FLAN issues be known as 'FLANtulance'?
Better links by OzPeter · 2013-01-31 04:38 · Score: 2

LED room lights will double as "Li-Fi" wireless nodes
Li-Fi Multi-tasking micro-lights could spark a communications revolution

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1. Re:Better links by clarkn0va · 2013-01-31 05:51 · Score: 1
  
  LED room lights will double as "Li-Fi" wireless nodes
  The great side benefit of that, that nobody seems to be talking about, is that living organisms can finally start to expose themselves on a routine basis to the low-level functioning of computer communication technology. In a mere few million years, we will have evolved to the point of comprehending the flickering of the LEDs, much the same as we now comprehend written and spoken communication.
  Who knows, maybe we'll even co-evolve some sort of organic signalling system of the same calibre, so we can eliminate the computer 'middle man' altogether!
  
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What is the advantage? by joe_frisch · 2013-01-31 04:48 · Score: 1

It requires line of sight or a limited number of bounces. Is it faster, cheaper, or lower power than conventional wireless?
1. Re:What is the advantage? by suutar · 2013-01-31 05:05 · Score: 1
  
  lower power, possibly. There are benefits to requiring line of sight, as well as drawbacks. You'd need more than one AP for a house, but you wouldn't have to worry about your neighbors stomping on your frequency.
2. Re:What is the advantage? by joe_frisch · 2013-01-31 05:12 · Score: 1
  
  I'd be surprised if it were lower power. RF is very efficient, and detectors very low noise. Basically RF detectors are limited by thermal noise ~1/40 ev, while photo detectors can't measure less than 1 photon (~1ev) and most are ~100X worse than that.
  Avoiding frequency congestion would be useful if the bandwidth is competitive with wireless.
3. Re:What is the advantage? by squiggleslash · 2013-01-31 05:20 · Score: 1
  
  It also requires that you actually want a light in whatever locations you plan to use this.
  That might seem like a "But everyone wants light!" thing, but actually the entire concept of lighting an area is something that has a lot of aesthetic complications attached to it that also have to be worked around. Yes, you want light, but you want it from a particular direction, you want it at a particular level, you typically want to be able to turn off some lights at certain times of day and night and turn on other lights.
  The entire advantage of radio is that it's invisible and doesn't otherwise impact a human being. Because it's invisible you can make it as strong as you need it and make it ubiquitous.
  
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Security by Registered+Coward+v2 · 2013-01-31 04:50 · Score: 1

Of course, anyone that can see the lights can monitor traffic undetected. Sort of or he old lihts on a modem.

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1. Re:Security by suutar · 2013-01-31 05:11 · Score: 1
  
  sort of like anyone with an antenna can monitor wifi traffic (max distance vs. through walls... *shrug* There's tradeoffs). For stuff that isn't essentially broadcast, I would expect encryption, just like (okay, better than) current wifi practice.
Amazing by Anonymous Coward · 2013-01-31 04:50 · Score: 1

Imagine what you could do with this kind of technology. Personally I could see dedicated cheap devices with which you could remotely control your TV, radio, and other appliances. The sky is the limit!
1. Re:Amazing by DarwinSurvivor · 2013-02-02 07:24 · Score: 1
  
  They already have these. It's just an IR LED connected to a usb or serial port and they're dirt cheap.
Creatures of the dark by WaffleMonster · 2013-01-31 05:02 · Score: 1

Or you can just buy 60ghz gear off the shelf today. The antennas are tiny, provides several gbits per device regardless of the number of devices. It has all of the same properties as visible light except you won't be destracted by it if you don't want the damn lights on.
1. Re:Creatures of the dark by GrahamJ · 2013-01-31 05:19 · Score: 1
  
  Agreed, I can't imagine how this would be better than 60GHz. Mind you I don't see a lot of point in either at home. Maybe someday I'll want to instal a device in every room so I can stream 4k video from a mobile device, but it sure as hell won't be anytime soon.
2. Re:Creatures of the dark by NatasRevol · 2013-01-31 06:15 · Score: 1
  
  Luddite.
  
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3. Re:Creatures of the dark by Graham+J+-+XVI · 2013-01-31 06:25 · Score: 1
  
  I hope that's in jest, if you knew me at all you'd know it should be :)
  I'm all for the bleeding edge but only if it's actually useful. I already have a few hundred megabits to my laptop, another gigabit or two really wouldn't change anything.
4. Re:Creatures of the dark by NatasRevol · 2013-01-31 06:32 · Score: 1
  
  Yes, it was a joke. EVERYone wants to stream 4k to their mobile!
  
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Channels? by bWareiWare.co.uk · 2013-01-31 05:09 · Score: 1

How would micron-LEDs allow more channels? If you are using different frequencies of light you wouldn't need them that small to cover the usable spectrum. If you are planning on resolving each pixel form the receiving device you certainly couldn't use micron sizes over any useful distance?
1. Re:Channels? by slim · 2013-01-31 05:36 · Score: 1
  
  I suppose it depends what you mean by "useful distance". I can imagine situations in homes or small offices where line-of-sight over quite short distances would be useful. I've had situations in some of my homes where I wanted something faster than WiFi, cable was messy, trunking/channeling was impractical. What if you could bridge those gaps with a pair of LED trancievers, the sensors focussed on the array of transmitters using a lens?
It's called "802.11" by tlhIngan · 2013-01-31 05:10 · Score: 1

The same 802.11 spec you use today initially specified another physical layer for wireless communication - using infrared.
Or it's technically one physical layer - just one is down in the 2.4GHz band and the other is way up there around 3THz or so...
A science fair project if I ever heard of one. by OneSmartFellow · 2013-01-31 05:21 · Score: 1

There's a reason people use Radio (and higher) spectrum. Maybe these guys haven't heard.
Article from The Economist by GrahamJ · 2013-01-31 05:27 · Score: 2

about this
Unregulated by Comboman · 2013-01-31 05:35 · Score: 1

The only thing I can think of is regulation. Unlike the radio spectrum, the light spectrum is unregulated so no need to worry about running afoul of the FCC and stay under certain power levels/frequency bands/etc. Also it might work in places where Wi-Fi doesn't due to RF interference (microwave oven factory maybe?) but generally there are other ways to fix that. Speaking as someone old enough to remember the colossal failure of IrDA which was based on very similar principles, I don't think this technology has much of a chance.

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Re:Epilepsy by BrokenCube · 2013-01-31 05:37 · Score: 1

photosensitive epilepsy?
We're talking millions or billions of flashes per second here - far far beyond the flicker fusion threshold. We won't be able to perceive it as anything less than a solid light source.
Re:You answered your own question already. by joe_frisch · 2013-01-31 05:39 · Score: 1

The problem is that it isn't a very secure limit unless you are in a light-tight room. If the system is modulating lighting LEDs, then it may possible to snoop on the AC power lines. I could imagine making the lighting system secure, but its not trivial. If you want security there are lots of encryption methods that are much more secure. If you are really worried about snooping (defense work), then you need a certified RF shielded room in any case.
It might be useful for separating bandwidth from different areas, but only if its total bandwidth is comparable to that of a modern wireless system.
Re:limited application by dave420 · 2013-01-31 05:44 · Score: 1

Light reflects wonderfully, so no.
Re:Epilepsy by Farmer+Tim · 2013-01-31 05:48 · Score: 1

Photosensitive epileptics are affected by high contrast, relatively low frequency flashes (well below 100Hz). A tiny LED switching so fast the most anyone is likely to see is a slight fluctuation in brightness (presuming it's not IR) would be less of a problem than the flashing LEDs on the front of existing routers.

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Re:Applications by rwise2112 · 2013-01-31 06:04 · Score: 2

This sounds ideal for low-bandwidth line-of-sight communications, like for example changing channels on a TV.
My God! That's brilliant! Control the TV remotely. What would be a good name for that?

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Re:Epilepsy by TheTerseOne · 2013-01-31 07:05 · Score: 1

so, didn't read the article,but what about people with photosensitive epilepsy? surely hundreds or thousands of flashes per second cannot be good for people with this ailment
And think about the Epileptic Dogs!

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Re:Applications by Anynomous+Coward · 2013-01-31 07:27 · Score: 2

Being able to control a tv using a remotely emitting, modulated, optically transmitting effector would be a great breakthough indeed.

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NRZ coding by enriquevagu · 2013-01-31 07:49 · Score: 1

C'on, this is Slashdot. Is it so complex to say that they employ an NRZ modulation using a light carrier, rather than "a bit like Morse Code from a torch"? Is it so difficult to refere to the switching/modulation frequency, or baud rate, rather than "they can also flicker on and off around 1,000 times quicker than the larger LEDs"?
The idea of using a LED light for communication is presented as a novelty in the summary, when all remotes work this way, and even the original 802.11 specs included a PHY layer that relied on IR. You are trying to make articles more dumb-user-friendly, but what you are getting is to kick out the users that might make valuable comments.
1. Re:NRZ coding by rubycodez · 2013-01-31 14:56 · Score: 1
  
  I can phase modulate the light from my torch by moving it back and forth in the direction of the observer, but my arm gets tired so I return to zero (RZ)
Micron-based huh? by Trogre · 2013-01-31 09:43 · Score: 1

Well I hope they're prepared for the impending patent litigation.

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Re:Epilepsy by sjames · 2013-01-31 10:43 · Score: 1

At that frequency, their retinas couldn't respond fast enough to produce anything but a steady on signal, just like looking at any constant source of light. That is distinct from the flickering of an old 60 Hz fluorescent that most people don't notice but can actually produce a variable signal on the optic nerve.