

Forget WiFi, It's LiFi: Internet Through Lightbulbs - aptsurdist
http://www.good.is/post/forget-wifi-it-s-lifi-internet-through-lightbulbs?utm_campaign=daily_good&utm_medium=email_daily_good&utm_source=headline_link&utm_content=Forget%20WiFi%2C%20It%27s%20LiFi%3A%20Internet%20Through%20Lightbulbs

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Afton
How do you avoid interference between devices?

Is this meant for receiver-only, or bidirectional transfer? (he says
bidirectional in the ted talk, but only talks about phones using their cameras
to receive).

Seems a little like a technology in search of a problem.

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lgeek
You avoid interference in the same way you avoid it for radio wave
communication: multiplexing. It could be time-based (time slots for each
sender), frequency-based (different colors) or code-based (look up CDMA).

Plus, you already have 'spatial multiplexing' because light doesn't pass
through walls as opposed to RF.

~~~
Geee
It's OFDM based transmission so OFDMA would be trivial to implement on this.
Like on Wi-fi.

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alex_c
Duplicate discussion here:

<http://news.ycombinator.com/item?id=2850288>

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dpryan
Fraunhofer recently demonstrated 800 Mbps through visible light as well.
[http://www.fraunhofer.de/en/press/research-
news/2010-2011/20...](http://www.fraunhofer.de/en/press/research-
news/2010-2011/20/data-traveling.jsp)

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alok-g
This is not a new idea. Saw a functional demo more than eight years back.
Checkout: <http://www.talking-lights.com/>

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isTravis
Completely correct. This is not a new idea at all. However TalkingLights had a
huge bandwidth limit because they used flourescent lighting.

LEDs can go to much higher speeds - but even still, this isn't new.
Researchers in Japan and Boston University have been producing demos for
years:

[http://www.bu.edu/smartlighting/research/smart-light-
prototy...](http://www.bu.edu/smartlighting/research/smart-light-prototype/)

<http://www.naka-lab.jp/index_e.html>

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narkee
>And security would be a snap—if you can’t see the light, you can’t access the
data.

That doesn't make any sense at all. People don't intercept data transmission
with their eyes. If your computer or device can "see" the light, so can mine.

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aptsurdist
I think the point of that statement was just that the data isn't transmitted
through walls.

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ugh
Certainly. It’s line of sight. It’s actually possible to visually see who will
be able to catch the data.

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muyyatin
Light bounces off of objects, and so this may not be true.

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fla
Does it means every light source is connected to a network cable ? If so,
where is the security ? All it takes is to find a network cable and intercept
the traffic. And there will be thousands of network cables in every building
(at least as many as power cables). For me 'security' sounds like false
advertising, in practice.

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geon
There is allready "network over power" adapters available to turn the power
wiring of a building into a lan.

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fla
It does not solve the problem. My point is there will be tons of vulnerable
cables, making it very hard to secure.

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zwieback
Kind of a cool idea - take IrDA to the next level. Probably no issue with FCC
regulations since the visible spectrum is kind of a free-for-all.

~~~
dpryan
It's also convenient in that it takes advantage of the existing infrastructure
if you're performing the communication with general purpose LED lamps, which
are being rapidly adopted for their energy efficiency.

~~~
simcop2387
I think the coolest part of this would be if someone were to take it and
combine it with a "standard" (I really don't know how standard it is)
Powerline ethernet setup. Would make for a more reliable than wifi setup in
some buildings while being easily compatible with existing hardware.

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tlianza
Gives new meaning to a programmer "going dark."

Well, same meaning I guess. Only literal.

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andrewcross
This blew my mind. It makes sense that light will be more controllable (think
lamps projecting photos onto a wall), but the light itself being an internet
source is trippy.

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Cushman
What have you been imagining WiFi is all these years?

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scotty79
Could you just solder LED and phototransistor to a proper place in you wifi
cards and achieve same goal?

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creativeone
Anyway to see this in action?

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asmithmd1
Here is a link to his TED talk

[http://blog.ted.com/2011/08/02/wireless-data-from-every-
ligh...](http://blog.ted.com/2011/08/02/wireless-data-from-every-light-bulb-
harald-haas-on-ted-com/)

It seems like a good idea but he does not address how to get the data to each
light fixture

~~~
dpryan
This is an open problem. The dream scenario is to utilize power line
communications, but that technology has its own set of issues.

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watmough
I already use Ethernet over household wiring to get data from the uverse
router to my wife's office. I think it's 200 Mbs, but whatever, it's
completely transparent to use. It may be the only completely foolproof piece
of hardware in the house.

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akmiller
I like to work in the dark.

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ajays
Put on some sunglasses.

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Kadrith
Would it work with a black light?

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dcheng
I really hope they don't use this to autopilot cars. That seems completely
reckless. If a terrorist happened to get an LED flashlight that disrupted the
transmission of whatever light signals were going to the autopiloted cars,
there would be chaos. It would be so easy interrupt these signals.

Thinking more about it, any signal "controlling" an autopiloted car would be
insecure and be an easy exploit that any malicious-minded people could take
advantage of. But that's a discussion that's besides the point.

~~~
dcheng
why the downvotes?

