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back to article WTF is... Li-Fi?

Reg Hardware Mobile Broadband Week Forget about Wi-Fi - the future of home wireless networking is, according to boffins, the light bulb. So say a number of researchers and technologists who are looking to light to provide the next step in high-speed data networking in the home. PureVLC D-Light The principle is simple: turn …

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Joke

Re: Doors

I have a networking solution that works with closed doors, but you have to shout very loud,

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switch that feckin light back on you cant!

Presumably any published speeds should be divided by two for when its daytime.

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Bronze badge
Paris Hilton

Car to car

Modulate LED tail and/or brake lights to inform the vehicle behind you of a panic stop. An ad-hoc mesh network can relay such data back to cars further back.

Paris, because getting rear-ended could be a thing of the past.

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Facepalm

What's the speed of light again, boys?

Can you say "multipath" from those modulated photons bouncing around the room? Gigahertz? I think not -- do the maths. Line of sight (such as inside a fiber waveguide) is super, but the splatter from your modulated desk lamp won't get you much bandwidth.

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Joke

I've already done this

Plugged a DC MR16 bulb into an AC transformer, unfortunately the only output I got was a steady stream of 'U's. 50 per second, to be precise.

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Headmaster

Re: I've already done this

Why, yes, I do have 400Hz house wiring.

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I'm sure this is probably covered by others, but .. seriously - this sounds great!

So there I am, putting on my media PC in the lounge room to stream a video onto the TV off some form of networked device (a fileserver in a distant room/youtube/some internet source/whatever). Now, when I watch movies, I like to turn off the lights for that full 'cinema experience'.

Nope, can't see a single problem with visible light design :/

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FAIL

As many lights in homes and in the UK are mini flourescent energy saving bulbs, due to EU Diktat, this won't work

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re: mini flourescent

LEDs are OK even w/ the EU, just (way) more expensive and the ones to get you to MHz xfer rate - even more.

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not detectable?

I'd want a lot of testing done before I'd allow all my lightbulbs to be flickering.

Even if it's too fast to consciously see I'd want to know that it wasn't going to end up causing splitting headaches before using it

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Anonymous Coward

Re: not detectable?

I'm sure there will be tests, I'm sure most of us can predict the results...

But all lights flicker, and just because some scientist using a brand new bulb in a lab can't see it doesn't mean I can't see the flicker from the much older tube in the office. (Though no one else seems to be bothered I need to counter it with sunlight to stop the colourful hallucinations induced by sitting under it 10 hours a day)

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Anonymous Coward

I predict a resurgence in happy hardcore as people start using strobe lights to deploy malware.

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Go

The lights don't have to be "on", or flicker

Late to the party, but I've seen the tech first hand. The flicker is a non issue - I am quite sensitive to flickering lights and don't notice anything when looking at them working, and the light is not modulated on-off, it's a much more complicated modulation scheme than that.

Also the light can still transmit data while it is not perceptibly on, the data rate might be lower but it can cope with quite high noise to signal ratios.

The people worried about moving from room to room: I think the lights will operate somewhat like mobile phone towers, on a more localised scale, where your connection should automatically switch to the most visible light source. This is just speculation on my part however.

Disclaimer, I'm loosely related to the Edinburgh project.

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Silver badge

"receive signals from digital billboards and domestic LED-backlit TVs"

Oh great, like we didn't have enough ad surface already.

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Joke

To answer your question, WTF is... Li-Fi?

Is it a high quality music reproduction system used in China?

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Bronze badge

Sat under an endlessly flickering light?

Isn't this sort of thing banned by the Geneva Convention?

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Anonymous Coward

I thought LED flickers enough for headaches as it is...

...this will lead to really sick buildings. Oh wait, no it won't because it's a silly idea and no-one will use it.

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Anonymous Coward

how do you...

Get the internet to your lightbulb? (for these super high speed data rates)

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Joke

No No ...

You won't be able to watch p0rns in the dark anymore.

Think!!!!

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Gold badge
Boffin

People have been trying this for years. LED's not needed.

IIRC Mitsubishi have patents for flashing the keyboard backlights of phones for reception by the ambient light sensor on other phones, again low bandwidth data like your phone book entry.

Likewise fluorescent lights in shops and meidal facilities have been looked at as LF comms for mobile devices, patient tracking and updating price labels in near real time.

The key phrase seems to be "smart ballast".

This sound like a gimmick to sell more LED's but I think non domestic lighting has a) a *huge* installed base and b) is fairly efficient. That makes a *lot* of market inertia.

Personally I quite liked a system to allow a daylight patrol of street lights. Any council vehicle could have a van top box that at normal road speed could pick up a data packet of up to about 1500 bits. More than enough to report if the the various parts are failing/failed and schedule a call out. Yes in many places the only way the local authority knows if a street light has blown is if it's reported by the public.

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Bronze badge

Re: People have been trying this for years. LED's not needed.

"This sound like a gimmick to sell more LED's but I think non domestic lighting has a) a *huge* installed base and b) is fairly efficient. That makes a *lot* of market inertia."

Two possibilities:

1: "Riding the wave". The guys behind this are running on the assumption that once LED pricing hits a certain sweet-spot, there will be a massive changeover, possibly pushed by new legislation on energy efficiency and/or mercury in manufacture and/or the workplace. If they have a mature(ish) technology before that happens, then they have an "in" to the market. They need to have their technology available for when everyone rewires, cos they're not going to rewire twice.

2: "Making the wave". They may feel that the increased efficiency of LEDs isn't going to be enough to convince people to swallow the cost of switching, but that this technology can help push the uptake of LEDs. "Double your office wireless capacity while halving your electricity bill." That's a lot easier to sell....

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Bronze badge

Seems to be a one way stream to me as theres nothing a bulb can do to recieve data

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Boffin

Let's speak geek.

"And light isn't affected by the spectrum regulations that govern how radio frequencies can be used."

I think what you mean is that light is in an unregulated frequency band.

Science!

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