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Using IR Lasers Instead of Fiber
Artifice_Eternity writes: "Can't deal with the trouble, time or expense of digging up the street to get fiberoptic cable to your building in the big city? There's another way...infrared line-of-sight infrared lasers between your building and another one nearby. Repeaters and redundancy can keep the chain going reliably for miles, with gigabit data transmission rates."
This is good for many reasons. The cost is
primarily in the one time purchase of the equipment. And it makes a lot of sense where line of sight is a shorter distance than a fibre cable must travel (tops of buildings in a congested city). These dont interfere with radio freqencies, so you don't have to concern yourself with noise, or creating noise. And its unlikely a backhoe will ever be a problem (as long as it doesn't block the line of sight).
The downside is the line of sight. You ALWAYS have to have line of sight. Rain, fog, clouds, trees, idiots with signs, they all can cause problems. Short distances are less of a concern, but you still have to maintain an almost perfect orientation. A little gust of wind can have you dropping packets.
But its probably a better solution than fibre where running fibre isn't an economically feasable solution. But no matter how good this is, fibre has far greater potential capacity, even though we don't yet have the technology to use all of it. It doesn't make sense to start building the internet backbone out of these things.
-Restil
Play with my webcams and lights here
Infrared line-of-sight links have been done for well over a decade. Datapoint's Arcnet had an infrared link device called Arclight that they used for a line-of-sight link for several miles. It would flake out in rain or fog - because rain and fog both absorb and refract infrared. So it might as well have been as opaque as black smoke.
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Arcnet was a self-healing token ring network with an underlying broadcast topology. So if two buildings were connected by Arclight and it went down, the network split into two rings, and when it came back up it healed into a single ring. Reconfig took miliseconds so it was no big deal.
You may not have heard of Datapoint. But have probably heard of the Intel. Seems Datapoint had a discrete-component standalone computer/smart terminal which was the basic node in their network - a diskless-workstation, fileserver, compute-server archetecture. They cut a deal with a semiconductor company called Intel to try to port their instruction set to a silicon chip for the next generation. But the resulting chip was too slow, so they went with another discrete component solution.
And Intel had cut the deal so they could sell the chip. So they took the chip to market, perhaps with a few tweaks, as the 8008 - first in the line that continued with the 8080, 8086, 80x86, Pentium,
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Yes, as many have commented this is old news. There haven't been any breakthroughs on this in several years. Let me rephrase that ... no significant breakthroughs.
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Once a year we have a customer come to us to ask about this option. Once a year we trot out our proposal, rerun the numbers and submit it. It always comes down to two things:
1) Speed
2) Reliability
The speed of the lines is fantastic when you have a clear day and relative distance is kept. Any atmoshperic conditions out of the ordinary will kill the line. Now, if you're only interested in using it for a mail gateway or to transfer data for a nightly batch cycle it rocks. For regular WAN access you'll be answering the phone from the folks on the floor.
Reliability is a concern past the speed. Keeping the connections is sometimes more an art than science. The article does have an interesting take on parallel transmissions, but commerically available products are cost prohibitive to make it a viable alternative for most businesses.
The best line from the article is: "Transmitting lasers through the air and modulating them at gigabit rates is a new and potentially powerful development," said Dr. Daniel Leslie, a physicist at Trex Enterprises who is familiar with the new systems.
Now, if you want to see something cool check out Dr. Leslie's company web page: http://www.trexenterprises.com/laserrad.html
If only we could work a Pringles can into this
This is why infrared is used instead of visible light. Infrared optics have been used for over a decade in night-vision systems, and the FLAIR system, which uses IR cameras to penetrate bad weather conditions as well as darkness, can be found on Apache attack helicopters.
So the only issue is having objects get placed in the way of the beam; not a big deal for companies that have line-of-site access from the roofs of their buildings -- the only things that'll get in the way thirty feet up are going to be new, taller buildings being built.
My company uses a similar setup (focused microwave rather than IR), and we're quite happy with it. We've had a few small one-second hicups, but that's because they are erecting a new building beween the ones we have radio links on (and yes, the new one is short enough to allow the radio to continue functioning).
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I Hit the Karma Cap, and All I Got Was This Lousy
I don't think having many repeaters ...
I think that for gamers 802.11b (or even 802.16 or whatever it is called) makes more sense - no aiming, no major configuration issues. Lots of repeaters if you want to spread over > 100 metres. Sure, anyone can tap in easily - isn't that the point?
Using lasers just complicates things and creates a whole lot more ways for the system to fail than radio frequency spectrum.
For gamers and more generally interactive communications a low ping is more important than huge bandwidth.
Probably the latency will be bad for gamers, but then again are you really suggesting that gamers will want some city wide network for gaming? If they are logging on to some sort of centralised server (ie., where you don't know who you are playing with) wouldn't hitting the internet directly make more sense? Fast connection through high speed routers with a wide audience to find a suitable opponent for a fragfest.
If its a LAN party type thing, then as per above - 802.11b or similar.
If you really need point to point communications, you can still use this sort of technology with a satellite dish and point the signal with similar line of sight accuracy. I know of line of sight RF communications in the 2.4 GHz band over kilometeres.
There is no cryptographic solution to the problem where the intended receiver and the attacker are the same entity.
have a look at here. they are selling this for years.
www.laserbit.hu
Utter Crap. As an Amateur Radio operator and RF design engineer, I can safely say that "wireless repeaters" don't attract lightning any more or less than any other rooftop equipment.
Also, If you're clever you could use fiberoptic feed from a source indoors, and be COMPLETELY electrically isolated from the rooftop.
Also, last time I checked, my Grandfather of 92 doesn't have a LAN in his house. (What, from the fireplace to the kitchen?)
-- You are in a maze of little, twisty passages, all different... --
laying fiber down in even a mildly metropolitan area cost around $70,000/mile no joke
Nope. Weather affects IR systems as well as visible light. Droplets in the air are a physical impairment to propagation, regardless of frequency. For light, at the higher end of the frequency spectrum, propagation is affected by the probability of getting "between" the rain droplets. About a 50-50 proposition at best.
At the other end of the RF spectrum, at microwave frequencies and lower, the lower frequency wavefronts are so large they don't see the droplets at all, or are only minorly distorted by them. So, microwaves work well 80-90 percent of the time in fog, rain, etc.
Anyway, that's why IR is called "night" vision, not "fog" vision.
-- You are in a maze of little, twisty passages, all different... --
Our system worked pretty well - it only covered about 300m, between 2 buildings. Rain wasn't that much of a problem though and we didn't get any fog while it was running. Snow caused some issues, but not enough to really give cause for concern.
What did cause problems were birds sitting on the equipment, and bird droppings which fouled up the receiver. The system was eventually put out of action by golf ball-sized hailstones.
You, yourself, can buy a several watt (yes watt) IR diode
Jesus!
I hope anyone using that kind of power makes sure they know what they are doing.
Because the IR beam is invisible your eye will not have a blink reflex to bright IR light. The first you will know about getting an eyefull of a powerful IR laser is when you blind yourself (or someone else)
You have no pain receptors on your retina.
Remember home made lasers can be an absolute bastard to align! A good staring point for information on home made lasers is Sams Laser FAQ
A good background to semicondutor lasers is Britney Spears Guide to Semiconductor Physics (Yep, its true! check out the link.)
Anyone quoted by a reporter knows how little they understand
Don't believe what you read is the truth.
1. During a good snow, it will not cross a street (200ft, +-10). (Commercial units. Had a demonstrable five mile range on a pretty day.
2. I don't know where you are located, but when it snows or rains here, it snows and rains pretty much all over the city (Anchorage, AK). Redundancy only works if a few of your transports get interrupted. Otherwise you get sit back and answer the user support line and make up excuses while watching the routes flap in the routing table.
3. Glass windows in many larger buildings are infrared mirrors. Heat loss reduction. Don't even think about the cost of changing one in a space-frame building. Equipment goes outside.
4. By the time we got "redundantised" and "routerised" to make the system even remotely reliable, paying the local one of the LECs for SONET transport was looking pretty good.
I might be tempted to use this where the sun shines a lot, or in large enclosed structures, or to some place completely inacessable by other means, but I don't think it's ready for prime time.
*whup* "Get along, little electrons. Heeyah!"