Using Visible Light for Data Transfer

James Evans writes "Wired has an article about a New Zealand company which has developed a technology to transmit data at speeds up to 400Mbps up to 4km. They are working to have it more resistant to changes in weather, as well as increasing the distance. It has a number of advantages, including lack of federal regulation of the spectrum, as it is of course, visible light." In related terrestrial networking news, waytoomuchcoffee writes "Science Blog reports that the backbone for the World's Fastest Network is up and running. It's a fiber optic 40 gigabit per second connection between Chicago and LA. Teragrid is a project by the National Science Foundation designed to link up supercomputer centers."

Comments

Fiber Optics

[GeckoFood]

We have been streaming voice data over fiber-optic lines for a while now, and even digital data signals for networking. This sounds like fiber-optic transmission without the actual fiber-optic line! Very cool, indeed.

Perhaps this is the future of truly wireless computing?

One thing the article states is that the current range is about 11 km. This seems a little short. However, considering this is a line-of-sight type of thing, that does make sense. Give 'em time, and they'll get it down to hundres of miles with good reliability, and then I think we'd see a bit move towards it for WAN technology and business usage.

Cool

[Timesprout]

Sounds like a cool technology clean, high performant, low infrastructure, does not slice limbs off or create two headed babies. This should make it a very attractive sell to commerce and to the public

I would have some security concerns though since it makes it a lot easier for those of malicious intent to intercept the signal as its basically being broadcast in the open. The technology would seem to lend itself naturally to strong encryption though.

I think they could be onto something big here.

A great idea

[Anonymous Coward]

The sooner we can get away from using out of date radio waves for data transfer the sooner the true broadband revolution will occur.

Consider this, most cellphones around the world operate at 1500MHZ and so have a seemingly impressive maximum THEORECTICAL data transfer rate of 750Mbits/sec. Unfortunately due to physical contraints on modulation systems a good rule of thumb is that the actual data rate provided is about 1/2000 of this and so we end up with around 375 Kbits/sec that is just coming out with 3G systems.

Now the optical band is out of the question for obvious reasons but if we could transmit in the THZ band or higher we could see massive improvements.

Consider this, going up as high as 10^16Hz would mean the PRACTICAL data rate going up to 5 Terrabits/Sec! Even a worst case senario would make multi megabit mobile data access available to all.

Now admittedly there is some problem with attenuation at these frequencies but this could simply be overcome by boosting the power. Overall it seems obvious that higher frequencies are the way to go.

Re:A great idea

[Anonymous Coward]

The problem (the way I understand it) is that higher frequencys don't travel through materials very well...

A crude example, sound waves travel through walls pretty easily. Shining a flashlight doesn't work too well.

To compare, from my experience, a 2.4ghz wireless setup can generally transmit more reliably than a 5.x ghz rig.

This light thang is cool, though definitely not a new idea. What they're doing is refining the tech. I think its great, throwing these up everywhere, with lots of redundant backups (in case one goes out) sounds like an excellent solution in an effort to continue beefing up the net's bandwidth. I'd love to see this technology available to the regular joe, just like the current wireless stuff is. With enough neighborhood participation, some killer private networks could be rigged up in no time ;D

Re:First Light?

[rasjani]

This actually allready happens...

... with satellite signals.

It is not even rare (atleast with biggest finnish cable provider). They are receiveing the signal via satellite most likely and when there's heavy snowstorm or rains, picture quality is really bad in some cases. So, anyone with cabledish themselves can verify this also ;)

Re:Federal Regulation

[Anonymous Coward]

Of course this can be regulated: "Transmission of information across property lines by technical means must follow the following regulations: bla bla." Just like with WiFi you could simply avoid premature outcry by having strict rules but lax enforcement (as long as no big business gets hurt).

Re:Fiber Optics?

[Anonymous Coward]

Not to mention dispersion, alignment, misalignment due to light tremors due to cars, wind, people.

Re:Disadvantages...

[blixel]

Security?

That was the first thing that occured to me when I read the post. It will probably be like everything else. First comes the technology, then years later everyone slaps themselves on the forhead for not thinking of making it secure from the beginning. Like Telnet, FTP, POP, 802.11, IM's, etc.....

Re:Lack of regulation

[mpe]

It sounds like a VERY nice system for short-range, non-critical communictaions, but personally, I can't think of any points I would want to communicate to where I have line-of-sight...

They give an example in the article. Where you need to communicate across a public road. (N.B. in New Zealand "motorway" means any surfaced road.)
Indeed any case where you need to communicate between several buildings fairly close together. Digging a cable trench is very expensive.

If I could get an inexpensive device that could communicate for about 10 miles, I would certainly get several.

They estimate that it can do up to 11km. With a single repeater 16km sounds plausable.

Re:Disadvantages...

[Anonymous Coward]

I don't think a video camera would achive much, unless you have a video camera that can record over 400 million fps.

Not security, but reliability...

[rasjani]

It could be as secure as wi-fi where the actual "media" is free for anyone to grap. What this means is that it requires strong crypto to be secure.

I think the realiability is bigger issue. What if someone wants to cut your operations. Big piece of carton or huge van to front of emitter could quite efectively cut it. How's that for denial of service ;)

Well, i admit that i havent read the article so i dont know how it actually operates but what about "light noise" from other sources.. Or other co-existing "light hubs" in the area. How do they effect the data and its reliability. Only way to prevent this (which i can think off) is using laser as transport medium light and thats not so new anymore is it. And DoS'n laser is even more simpler since the lightbean is really narrow usually and doesnt spread as "normal light".

Re:Not security, but reliability...

[Catbeller]

On the other hand, you might use a prism to create a 'tap' into the network. Or maybe a 3 port hub.

The cool thing about an optical line-of-sight transmitter: by hauling yourself to the roof with a pair of binoculars, you can look directly down the link and SEE the NSA/FBI/CIA/local cops' prism tap.

With WiFi, you never know if a tap is sitting in a van down the street, or the local 7-11 has an NSA tapping station behind the storeroom.

But optical, ah, you can SEE the buggers listening in on your conversations.

Snicker. Wouldn't it be cool if you could jack the power on the laser, and melt the bastard's tapping opticals? Priceless.

Already done at Xerox PARC

[phillymjs]

I just read about this the other day in the book "Dealers of Lightning" (page 140). While they were developing the laser printer in the 70's, some of the researchers had to move to a different building 1KM away. They had line of sight between the two locations, so they rigged up a system of lasers and photodetectors to bridge their network between the two buildings.

The beam went over a public highway, and after one woman went into a ditch after it startled her one foggy morning, they coarsened the beam to make it invisible.

What about right of way?

[Carnivorous Carrot]

We set up a microwave link between two buildings several miles apart. We had to get a right of way from all the land owners inbetween.

I wasn't involved directly in that project, so I don't know if it was needed because it was microwaves, or just in general.

I wouldn't rush to think this is some sort of easy method to solve problems, though.

Hope they think of this...

[Wylie Coyote]

Visible light huh? Like... I can see it? Hmmmmm. Hope someone thinks to encrypt it :)

How 'bout redundancy.

[Anonymous Coward]

It's easy to block 1 path. But if you have 10 or 20 light paths, it becomes less probable all of them are blocked. And making the lights in the invisible spectrum is a good idea.

Re:Federal Regulation

[nolife]

I know the local law enforcement gets away with it but to me it still does not seem justified. That's like telling someone not to steal and being charged with obstruction. They are not doing any justice until after they catch you actually speeding. You flashing your lights at a motorist does not automatically mean that the driver was even speeding or breaking any law to begin with and even if they were, the police would have to prove it first. Now if they are chasing the speeder after the fact and you get in the cops way they have a reason to charge you. Why don't they charge every person with a CB that discusses where the police are? What if you stood up the road with a sign in your hand? What about a local radio station that announces it? Can they hand out fines for that? A locality that has a practice like this has the wrong idea of what a speed limit is for. Speeding tickets, limits and fines are not supposed to be income for the police and communities, they are there to promote safety. The goal is to provide police presence and get you to slow down in areas that need extra attention. Targeting individual cars or ticketing someone who might be warning someone to slow down does not meet that goal and really does not make any sense at all. Areas that treat it as income probably have artifically low speed limits that make it even worse.