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UK Researchers Build Micron LED Light Based Wireless Network

timothy posted about a year and a half ago | from the stay-in-sight-of-the-tower dept.

Networking 70

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 (5, Funny)

slim (1652) | about a year and a half ago | (#42751521)

(a bit like Morse Code from a torch)

Thanks for the clarification, News for Nerds.

Re:Transmitting binary data using a flashing light (1)

OzPeter (195038) | about a year and a half ago | (#42751713)

(a bit like Morse Code from a torch)

Thanks for the clarification, News for Nerds.

Unfortunately that description is in TFA

Re:Transmitting binary data using a flashing light (1)

wonkey_monkey (2592601) | about a year and a half ago | (#42752119)

If only there was some alternative to blindly copying and pasting a few paragraphs from the article when crafting a Slashdot summary...

Re:Transmitting binary data using a flashing light (0)

Anonymous Coward | about a year and a half ago | (#42752351)

That takes a skill-set that many people don't have. We're all great repeaters though! Yay us.

Re:Transmitting binary data using a flashing light (1)

NatasRevol (731260) | about a year ago | (#42752953)

Yay us!

Re:Transmitting binary data using a flashing light (1)

LocutusMIT (10726) | about a year ago | (#42754359)

Like Fry! Like Fry!

Wavelength (1)

i kan reed (749298) | about a year and a half ago | (#42751601)

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.

Re:Wavelength (1)

Anonymous Coward | about a year and a half ago | (#42751959)

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.

Re:Wavelength (1)

hardie (716254) | about a year and a half ago | (#42751985)

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"?

Re:Wavelength (0)

Anonymous Coward | about a year and a half ago | (#42752505)

You can't read. He talks about sending it to the other side of a wall. He sure isn't anything like correct.

Re:Wavelength (1)

TheGratefulNet (143330) | about a year ago | (#42753215)

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.

Re:Wavelength (0)

Anonymous Coward | about a year and a half ago | (#42759085)

You can get a lot more speed out of that low grade part if you design your circuit around for the purpose but that requires some more work than just trying it out.

Re:Wavelength (1)

citizenr (871508) | about a year and a half ago | (#42752445)

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

Re:Wavelength (1)

dave420 (699308) | about a year and a half ago | (#42752533)

The receiver doesn't have to know from where the signal originates, so a simple detector of the used wavelength would suffice.

Re:Wavelength (1)

DarwinSurvivor (1752106) | about a year and a half ago | (#42772641)

Funny, my remote control (same technology, slower data) works from tens of METERS away.

Re:Wavelength (1)

suutar (1860506) | about a year and a half ago | (#42752023)

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.)

Re:Wavelength (1)

stewsters (1406737) | about a year and a half ago | (#42752143)

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.

Re:Wavelength (0)

Anonymous Coward | about a year and a half ago | (#42752359)

It doesn't stop them from sniffing if you have windows.

ROFLMAO and its true.

Re:Wavelength (0)

Anonymous Coward | about a year and a half ago | (#42759099)

Great argument! You shouldn't put a lock on your door because it won't help if they have an axe!
Also, don't bother with health insurance because that won't help if an asteroid hits the planet!

This will be the end of the human race (0)

erroneus (253617) | about a year and a half ago | (#42751623)

Someone will transmit some data and unwittingly hypnotize the whole population. Skynet will, at about the same time, become self-aware and instead of killing all humans, become Skynet's slaves.

I have a better name for that... (3, Funny)

Zaatxe (939368) | about a year and a half ago | (#42751625)

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

Re:I have a better name for that... (0)

Anonymous Coward | about a year and a half ago | (#42751783)

so Fi-Fi...

Hope you're ready for poodle jokes.

Re:I have a better name for that... (0)

Anonymous Coward | about a year and a half ago | (#42751913)

Well, the original (and arguably the correct) name of "Wi-Fi" is "WLAN", for "Wireless LAN". Correspondingly the best name for this would be "FLAN" ("Fiberless LAN").

Re:I have a better name for that... (1)

Beorytis (1014777) | about a year and a half ago | (#42752519)

Correspondingly the best name for this would be "FLAN" ("Fiberless LAN").

So early adopters will be Mexican restaurants?

Re:I have a better name for that... (0)

Anonymous Coward | about a year ago | (#42753339)

and McDonalds worldwide

Re:I have a better name for that... (1)

DroolTwist (1357725) | about a year ago | (#42753353)

Will FLAN issues be known as 'FLANtulance'?

limited application (0)

Anonymous Coward | about a year and a half ago | (#42751639)

seems that unlike Wi-Fi, itll require a direct line-of-sight

Re:limited application (1)

dave420 (699308) | about a year and a half ago | (#42752547)

Light reflects wonderfully, so no.

Optical telegraph redux (0)

Anonymous Coward | about a year and a half ago | (#42751651)

This sounds like a new spin on the optical telegraph networks that sprang up around Europe shortly after the French Revolution. Human operators stationed in signal towers handled the sending, receiving, and forwarding. It was fairly successful but suffered from the same drawbacks that are described in TFA, i.e. obstruction, poor visibility conditions, etc, plus obviously some additional ones that aren't issues with these newer devices. They became obsolete when Morse and his English counterparts rolled out electric telegraphs in the mid 19 century.

This is described in the book "The Victorian Internet".

What happens if (0)

bobstreo (1320787) | about a year and a half ago | (#42751691)

you're not a basement dweller and actually have windows in a room with these?

I know, not as much a problem in the UK, so they probably didn't check into this potential issue.

Re:What happens if (0)

Anonymous Coward | about a year and a half ago | (#42752277)

Well, if there are problems using this technology with windows, just restrict its use to linux and mac. :-)

Applications (0)

Anonymous Coward | about a year and a half ago | (#42751719)

This sounds ideal for low-bandwidth line-of-sight communications, like for example changing channels on a TV.

Re:Applications (2)

rwise2112 (648849) | about a year ago | (#42752841)

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?

Re:Applications (2)

Anynomous Coward (841063) | about a year ago | (#42753853)

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

Better links (2)

OzPeter (195038) | about a year and a half ago | (#42751749)

Re:Better links (1)

clarkn0va (807617) | about a year and a half ago | (#42752621)

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!

Epilepsy (0)

Anonymous Coward | about a year and a half ago | (#42751791)

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

Re:Epilepsy (1)

BrokenCube (896491) | about a year and a half ago | (#42752489)

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:Epilepsy (1)

Farmer Tim (530755) | about a year and a half ago | (#42752591)

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.

Re:Epilepsy (1)

TheTerseOne (2447418) | about a year ago | (#42753581)

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! [youtube.com]

Re:Epilepsy (1)

sjames (1099) | about a year ago | (#42756291)

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.

What is the advantage? (1)

joe_frisch (1366229) | about a year and a half ago | (#42751875)

It requires line of sight or a limited number of bounces. Is it faster, cheaper, or lower power than conventional wireless?

Re:What is the advantage? (1)

suutar (1860506) | about a year and a half ago | (#42752067)

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.

Re:What is the advantage? (1)

joe_frisch (1366229) | about a year and a half ago | (#42752171)

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.

You answered your own question already. (0)

Anonymous Coward | about a year and a half ago | (#42752141)

It requires line of sight or a limited number of bounces. Is it faster, cheaper, or lower power than conventional wireless?

Requiring line of sight (or a few bounces) is the advantage - strictly limited range, easily constrained by commonly available and understood end-user technologies called "doors" and "walls".

This is what bluetooth promised, and sort of sometimes delivers - under ideal conditions and absent malicious hackers. Surely you can see applications for a technology that visibly limits broadcast range?

Re:You answered your own question already. (1)

joe_frisch (1366229) | about a year and a half ago | (#42752503)

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:You answered your own question already. (0)

Anonymous Coward | about a year ago | (#42756097)

The problem is that it isn't a very secure limit unless you are in a light-tight room.

Thus, dramatically more secure than any RF technology in real-world deployments. You want to see if a room's light-tight, all you need is a sunny day (turn off the lights and use your eyeballs to find leaks) or a dark night (turn on all the lights and go outside). RF being invisible means you have to trust instrumentation that cannot be trivially validated, therefore it is (in practice) far less securable.

If the system is modulating lighting LEDs, then it may possible to snoop on the AC power lines.

If so, ten bucks worth of line filtering components will fix that problem.

Re:What is the advantage? (1)

squiggleslash (241428) | about a year and a half ago | (#42752293)

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.

Unregulated (1)

Comboman (895500) | about a year and a half ago | (#42752465)

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 [wikipedia.org] which was based on very similar principles, I don't think this technology has much of a chance.

Security (1)

Registered Coward v2 (447531) | about a year and a half ago | (#42751889)

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

Re:Security (1)

suutar (1860506) | about a year and a half ago | (#42752157)

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 (1)

Anonymous Coward | about a year and a half ago | (#42751895)

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!

Re:Amazing (1)

DarwinSurvivor (1752106) | about a year and a half ago | (#42772665)

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 (1)

WaffleMonster (969671) | about a year and a half ago | (#42752041)

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.

Re:Creatures of the dark (1)

GrahamJ (241784) | about a year and a half ago | (#42752267)

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.

Re:Creatures of the dark (1)

NatasRevol (731260) | about a year ago | (#42753037)

Luddite.

Re:Creatures of the dark (1)

Graham J - XVI (1076671) | about a year ago | (#42753169)

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.

Re:Creatures of the dark (1)

NatasRevol (731260) | about a year ago | (#42753241)

Yes, it was a joke. EVERYone wants to stream 4k to their mobile!

Channels? (1)

bWareiWare.co.uk (660144) | about a year and a half ago | (#42752125)

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?

Re:Channels? (1)

slim (1652) | about a year and a half ago | (#42752479)

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" (1)

tlhIngan (30335) | about a year and a half ago | (#42752149)

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...

Re:It's called "802.11" (0)

Anonymous Coward | about a year ago | (#42756623)

Its the signal penetration that is a bitch. don't need alot of power for 2.4GHz through a wall, this 3THz version has some serious issues with going through walls, mainly because at that point, you just made a laser cannon.

Would be really useful for deep space and point to point comms though

A science fair project if I ever heard of one. (1)

OneSmartFellow (716217) | about a year and a half ago | (#42752307)

There's a reason people use Radio (and higher) spectrum. Maybe these guys haven't heard.

Re:A science fair project if I ever heard of one. (0)

Anonymous Coward | about a year ago | (#42752835)

Tons of smart people are involved with goofy projects these days. Some of these projects pay off, and the one's that don't are still keeping quality minds engaged and growing.

Article from The Economist (2)

GrahamJ (241784) | about a year and a half ago | (#42752373)

about this [economist.com]

What a bright idea! (0)

Anonymous Coward | about a year ago | (#42753457)

This sure seems like a BRIGHT idea.

NRZ coding (1)

enriquevagu (1026480) | about a year ago | (#42754115)

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.

Re:NRZ coding (1)

rubycodez (864176) | about a year and a half ago | (#42757997)

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)

Wifi was stupid. (0)

Anonymous Coward | about a year ago | (#42754177)

So is lifi.

Micron-based huh? (1)

Trogre (513942) | about a year ago | (#42755519)

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

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