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Hardware

Fiberless Optical Networks 143

Posted by emmett from the neat dept.
Alien54 writes "According to this Forbes Magazine article, the time for Fiberless Optical Networks may have arrived. Wireless optics have been given up for dead until very recently. But now better technology and lower product costs have enabled some to solve most of the problems. AirFiber (a company mentioned in the article above) is emerging as one of the favorites in wireless optics, and seems to have a set of good answers for the inevitable "bird and fog" questions: Can a flock of birds take down a network by flying through the lasers? Can a heavy fog send your precious information into the ether?"
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Fiberless Optical Networks More

Fiberless Optical Networks

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  • Damn straight it dosen't make sense. But then again alot of things don't make sense. Like why in the hell some many people are using windows. (Hey it's my first bash MS post on slashdot.)
  • Are you sure (because I'm not) that you're not confusing the origins of TCP with the origins of Ethernet?
  • Sounds a bit like some of the problems they had with microwave transponders, except you don't get ready cooked pidgeon/sparrow/seagull for lunch.

    Give me microwave anyday...

  • No, shit-for-brains, the poster said wireless system. Of course he's wrong, but that's not the point.

    Pay attention to the words.
  • Your failure to grasp the point is astounding. Of course you wanted to say something. Your use of the moronic "go for it" to justify your irresponsible behaviour, followed quickly by the ironic "Go write something meaningful," speaks volumes.
  • Actually, in addition to increasing the power of the lasers, they should use the newly developed green diode lasers instead of the boring IR ones. If enough buildings used them, we would get to see a nice laser light show each night :)

    Wouldn't this make your network a easy target for packet sniffing? All that a potential culprit need to is to point his/her own sensor skyward and they have read full access.

    Similarly it would be trival for such an attacker to send their own data, issuing their own commands to machines etc...

    This scenario, to me, obviates the need for encryption in such systems, increasing cost and complexity.

    Having made these points, I realise that the problems apply to any unguided media (e.g. microwave links) and not just to 'open' light systems.

  • Will eating "wireless fiber" help me stay online and regular?

  • Actually, the light coming out of the top of the Luxor in Las Vegas (not a laser, but highly collimated) has been known to kill a few birds now and then.
  • The wavelength of the laser is 780nm. AirFiber uses the same type of semiconductor laser as that used in writable CD-ROMs. So does this mean that I can hack my redundant writeble CD-Rom drives into a redundant 622 Mbps Fiberless Optical Network?? COOL!!
  • And when we do, is it going to have the same limitations that the present ones do? Could different light frequencies be used to allow 'fuzzy' rather than binary computation? Or more importantly, could the instantaneous 3D alteration of circuts allow people to 'evolve' intellegent computers like the circut boards that were 'evolved' to recognize a specific tone without a clock. ... don't have the link handy. It was in Discover about 2 years ago if anyone knows what I'm talking about. Kind of like evolving an algorithm, but on the hardware scale. Also, where are the replicators? I want food and all the restaraunts are closed, dammit. If I had a matter transporter I could go somewhere where it was daytime. And a warp drive would be nice, too--cut down on commute time!
  • I am very sure. Terminal Control Protocol was designed by the U.S. Army for use with wireless teletype terminals.

    It ofcourse under wnet many changes during the years (integration with NCP, changes to accomidate the OSI model), but it had its humble origins way back when.

    Read Stevens.

  • that's old stuff (Score:3)

    by Anonymous Coward on Sunday August 20, 2000 @10:47PM (#840901)
    Hi, just want to tell you that this laser thing really is old. Here at Aachen (in the very western part of Germany) the student hostels "Die Türme" [rwth-aachen.de] (the towers, called so for being the four heightest buildings here in Aachen) of the technical university RWTH [rwth-aachen.de] use such a laser to connect their local network via the laser with the main computer facililty of the RWTH and the web. The laser is about 4 years old and has a max. bandwith of 40Mbit. And yes, fog and heavy rain is a problem. Have a look at: http://www.oph.rwth-aachen.de/ag/netzwerk/technik/ laser.html for the technical data and here, you'll get a picture: http://www.oph.rwth-aachen.de/ag/netzwerk/technik/ laser.bilder.html (No, that's not me on the picture) . Sorry, all pages are in german.
  • by physically dipping into the lightstream with a dental mirror attached to an optic? (Kewl!)
  • it is wireless because it doen't use wires.

    Actually, the article and the summary above call it Wireless Optics, not Wireless Fiber. It uses Optical technology without using Fiber Optics. It uses lasers.

    The rest is the attack of the marketroids, I suppose

  • Not the birds or the fog. But if this is takn up by a lot of ppl/companies, will we not see bandwidth pollution similar to what is/happening with devices that operate in the 3G spectrum? The portable (not mobile) phones, the radio lan cards that are made, the airport (from apple)(yeah bastratdised radio lan cards), [perhaps the previous could be summed up as 802.11].??


    .sig = .plan = NULL;
  • No, X-rays wouldn't work. 1) X-rays are difficult to deal with - focus, detect, etc. Normal mirrors don't work for X-rays, you need special mirrors and use blazing angle reflections otherwise the X-rays just pass right through your mirror. 2) X-ray detectors are still a work very much in progress, and generally you won't get both time resolution and frequency resolution, which are cruical in this game.
  • Say you put one up on your building. Then you have one connection to the main office. How are you gonna convince other companies to put these up on their buildings so that YOU have a reliable network connection? Especially at 20G a building.

    Although, laser tracking, laser power adjustment, and redundant paths are a good way to combat the previous problems with laser networking.
  • Thing I'm wondering is what is the maximum available bandwith with an unladen african swallow, hmm?

    Zero. If it's carrying any data, it would therefore be a laden swallow. It doesn't even enter into it if it's African or European.
  • re: Item 4 -- what height are you assuming? Mountains, to take an extreme case, are visible for quite a bit more than 7 miles!

    I found an horizon calculator here [fas.org], and at a height of just 50 feet (which is what, a 5-story building?) the horizon is ~9.5 miles.

    This might be an issue in a suburban office park, but even here in little Baltimore we've got plenty of buildings higher than that. In particular, the World Trade Center in the harbor (which would never be confused with ones in New York) is 423 feet tall, giving an horizon of some 27 miles.

  • The buildings are about 1/2 mile to a mile apart. 10mw Output power.

    More info here: http://www.astroterra.com/
  • Fog is bad enough. What about people actively trying to do bad things to the network? Forget hacking. Just set off a smoke bomb. And what about packet sniffing? Send a model helicopter with an optical receiver to intercept the data...
  • I know that AirFiber has had functioning networks, many of them numbering hundreds of nodes, for several months now around the world and in use. Right this minute, internet packets are going through AirFiber nodes in real-world use.

    So while you're sitting there telling us that it's all vapor and research, while companies around the world are currently using AirFiber technology to provide internet service.

  • Links you might want to look into...

    http://atrey.karlin.mff.cuni.cz/~clock/r0nj4/
    h ttp://www.alphalink.com.au/~derekw/upntc vr.htm
    http://www.hut.fi/Misc/Electronics/circuit s/laserlink.html
    http://www.geociti es.com/SiliconValley/Lakes/7156/laser.htm
    http:// members.mint.net/n1bug/tech/laser/lase rfr.html
    http://opencollector.org/
    http://www.re pairfaq.org/sam/lasersam.htm
    http ://www.qsl.net/k3pgp/opening.htm

    The first link actually seems to be the best - instead of lasers, ultra-high brightness LED's are used - no great distances here, but aiming doesn't have to be as accurate, fog/rain/birds are less of a problem, the hardware interface is rather simple, and the LED's (and other parts) are cheap!

    I support the EFF [eff.org] - do you?
  • "Most likely, yes. Anything that interrupts or degrades the signal will be a problem. What about thunderstorms, which tend to emit on a lot of frequencies?"

    I don't know much about the other companies, but I know with AirFiber:

    * Birds are not an issue; signals are rerouted (the network is redundant) as soon as the connection is broken, which then automatically relinks;
    * Fog hasn't been a problem. Look at it this way -- if you can see a flashlight shining through the fog, you can see this laser.
    * How would thunderstorms be a problem? We're not talking about RF frequenciese here!
  • re: Item 4 -- what height are you assuming? Mountains, to take an extreme case, are visible for quite a bit more than 7 miles!


    I found an horizon calculator here, and at a height of just 50 feet (which is what, a 5-story building?) the horizon is ~9.5 miles.

    This might be an issue in a suburban office park, but even here in little Baltimore we've got plenty of buildings higher than that. In particular, the World Trade Center in the harbor (which would never be confused with ones in New York) is 423 feet tall, giving an horizon of some 27 miles.

    You are right, of course, but there may still be other obstructions in the way. And, of course, with greater and greater distance (and higher buildings) sway is much more of a problem. I daresay with a 2-story building over 1/2 to 1 mile distance, sway is not an issue, but atop the World Trade Center the sway can be several feet.

    Add to this the fact that even a laser will spread and scatter greatly after a distance as great as 27 miles. For various reasons, it's unlikely that optical wireless can be made to cover great distances any time in the immediate future.
  • "Who's going to try it first?"

    Several companies are already currently using AirFiber's system.
  • It'll be a little longer before they're obsolete.

    I'm posting this over a (gasp!) 14.4Kbps modem because my cable modem service has been out for the last 18 hours. (ObIrony: the customer support line is just a recording, and the ISP's advice when your cable modem isn't working is to send e-mail to tech support.)

    Meanhile the phone company keeps calling to sell us ADSL, but once the order is placed they forget all about it. (This has happened three times this year already.)

  • The problem is not the cost of materials; the problem, especially in cities, is in waiting for city bureaucracy to give a permit, paying a huge fee for the permit, digging up and later replacing concrete and steel to lay the cable, inch by inch, block by block. This gets ludicrously expensive even over inconsequential distances.
  • You will be amazed by your wide bandwidth, high flowthrough downloads. (ouch, sorry.)
  • I haven't heard that TeraBeam has any solutions to these problems, but I know the folks at AirFiber have. As they mention in the article, they space the R2D2s based on weather patterns in the area.
  • Well, cetainly there are constraints on the range of such a signal. I just think that the Earth's curvature would be among the least.

    Does anybody have figures on how much a well-focused laser will spread? I seem to recall that when you bounce it off the Moon, the area covered is measured in square miles, but I haven't looked it up.

    I'm guesing that atmospheric conditions (and other buildings) represent the biggest obstacle.

  • Thing I'm wondering is what is the maximum available bandwith with an unladen african swallow, hmm?

  • Birds and Fog (Score:1)

    by Anonymous Coward
    Most likely, yes. Anything that interrupts or degrades the signal will be a problem. What about thunderstorms, which tend to emit on a lot of frequencies?
  • Yup, thats pretty much how it works. the glasses generally work much the same way night vision glasses work, except that night vision glasses aplify visible light, whereas these would amplify light at frequencies that correspond to the laser you wanted to look at.
  • Running a 30 mile cable takes several months to a year. Running a laser for 30 miles would take a few weeks at most. To calibarate it, it would only take a few days.
    until (succeed) try { again(); }
  • A classic example of this type of problem can be seen on our nation's (United States) highways (bear with me). Back in the dark ages, before the national highway system was built, people tended to settle near their places of employment. As the suburbs grew, the need for a larger traffic infrastructure became apparent. As a result, the highways were built; however, in many cases they were built with a) old technology b) poor planning for future growth and c) limited space. Now we're in the middle of huge construction projects all over the country to deal with these issues. Once again bear with me... So what does this have to do with IP networking, specifically wireless networking? Well - the issues are the same. As the demand for high speed connections grows (especially in residential areas), the infrastructure will have to mature. Due to space constraints, cost of land lines and other things mentioned by earlier posters, we can't really have new land lines sprouting up wherever. Not only that, but it's not in our best interests. Any solution will become obsolete someday, but wireless systems are more applicable to the situation at hand; if we are unable to adobt such strategies, we'll face similar problems on the Internet than what we do on today's highways. If anything I said wasn't apocryphal and totally based on opinion rather than fact, I apologize. I'm really looking for a forum to b*tch about the fricking construction project right near my house.
  • by ramping up the power but people might complain when we run out of birds.

    Also it could get messy for a while what with all the headless pigeons and arms of careless windowcleaners falling about the place.

    Bob.
  • That really doesn't make any sense--therefore, invest in it!

    I now have incredibly high-tech phone misdirection and blocking devices! They're called "prisms".

    Oh well. Even if it *does* work, my phone card still won't be activated, and I'll have to call the company somehow to tell them my phone service doesn't work...

    I liked the paper-cups-and-string method much better. And I didn't have to rent the string! What am I doing now, leasing the air?
    ---
    pb Reply or e-mail; don't vaguely moderate [ncsu.edu].
  • I hope this doesn't sound like a troll because I mention "Beowulf Clusters", but wouldn't optical wireless communications systems be better employed in indoor and predictable environments to provide high speed communications in examples such as clusters then in the outdoors?

    The abandoning of wires would save hours of diagnosing faults within wire connections for network administrators, and a laser data transmitter could be physically repointed at a different reciever with ease without even having to unplug cables and reconnecting them. With so much potential for this market, why is Air Fiber focusing on the outdoor market when they could perfect this technology for indoor usage with much less cost?

    This idea also reminds me of the concept, which has been purported for years, that wireless optical could become the next medium for data transfer within a computer's processors once silicon had reached it's the height of potential. Whatever happened to those projects?

    MashPotato - Mobile Array of Support Helpers for Potato

  • Re:Bandwidth Pollution:: (Score:3)

    by Chic Pea ( 153193 ) on Sunday August 20, 2000 @06:24PM (#840929)
    Not the birds or the fog. But if this is takn up by a lot of ppl/companies, will we not see bandwidth pollution similar to what is/happening with devices that operate in the 3G spectrum? The portable (not mobile) phones, the radio lan cards that are made, the airport (from apple)(yeah bastratdised radio lan cards), [perhaps the previous could be summed up as 802.11].??

    What you are thinking of is the RF (radio) spectrum. Since it is broadcast, it is regulated, and yes it is being used up.

    This, however is a point to point laser beam... (as in light... a totally different part of the EM spectrum) the only other station receiving the beam is where it is pointed.

  • This would be great (Score:2)

    by Anonymous Coward
    I work for a major Internet bandwidth carrier and know how long it takes to get fiber/DS1s/DS3s provisioned both in and out of the US -- for freeking ever. Totally unacceptable times for the fast moving business of technology that we all work in. DS3 in a month is a total miracle. DS1s get installed after about 6-9 weeks on average. Our customers get really impatient, and there is nothing that we can do because we rely on the Local Exchange Carriers to get the line to the customers. Getting the customers to the core is not an easy job.

    Having the ability to point a laser at some building across town, having been able to set it up in three days or less, would be flippin' awesome. Think about how great this would be for one time conferences and setting up temporary solutions. Who cares if it is not totally stable -- birds, fog, and your occasional script-kid gone cute with a big kite, trying to knock out your service.

    The building at which I work does in fact have a wireless (not optical) Sonet connection, along with standard OC12s and OC48. It should be noted that the city which I work and live also is a current test bed for Sprint and their wireless broad band solutions (also not optical in nature). These are excellent and very viable solutions for a quick connection.

    It should be noted that I had moderator points and *really* wanted to moderate up http://slashdot.org/comments.pl?sid=00/08/20/22342 00&cid=5 because I thought it was just plan funny, even for a troll post.
  • No, the labor costs more then it costs for an expensive laser. Plus, if someone digs a line up, think about the problems that causes.
    until (succeed) try { again(); }
  • This is a very good point. If a fiber line is obsolete, if needs to be dug up and what not. A wireless system just needs to be replaced.
    until (succeed) try { again(); }
  • Irresposible? Are you my mom? This is a comment site for news. You are taking it far too personally.

    Guess I've offended the "community." Bet something whitty is coming my way. Woo hoo. Don't forget to tell your friends.

    Oh yeah. I believe the sympatico internet is available only in Toronto right now, but it will be great for cottage country.

    Even the samurai
    have teddy bears,
    and even the teddy bears

  • Well, I suppose I should. For that matter, I'll read Cerf tonight (his paper w/ Kahn is on his site, [wcom.com] but in facsimile form, which makes for tough reading!)

    I confess I thought perhaps you were recalling Ethernet's influence from AlohaNet and the collision detection / avoidance needed in a broadcast network.

  • And would you have to put window cleaners on danger pay?

    "When I'm cleaning windows .... agggghh me arm!!!"

    Bob.

  • Re:Classic fiber channels not dead (Score:3)

    by ostiguy ( 63618 ) on Monday August 21, 2000 @01:32AM (#840936)
    People may use wireless optical stuff to simply avoid dealing with awful phone companies. Our t1 is upheld by the Verizon fiasco (may be in Fri) now. Att *could* do frame relay for us, as it is 2k for the drop and 1900 a month, in 30 to 45 business days. To expedite the delivery to 15 days, they want to bump us up to national service, so that would be 7k for the drop, and 5300 a month on a 36 month term = a 200k over 3 yr. commitment. We are actively looking at the lucent wireless gear, but building height on our new site is a problem.

    Its misery like this that will help push people to find new high bandwidth solutions.

    matt
  • What about health risks to humans? If someone acidentally points the laser at me eye, will I go blind?

    I'm not being sarcastic, either ... I think that lasers could be dangerous. Even those laser pointing pens that kids love playing with can cause retina damage.

  • Can a flock of birds take down a network by flying through the lasers?

    Can a network take down a flock of birds that are flying through the lasers?

    Now that would be cool.

  • if.... (Score:3)

    by maroberts ( 15852 ) on Monday August 21, 2000 @02:21AM (#840939) Homepage Journal
    const double MAX_POWER=500.0*ONE_MEGAWATT
    const double NORMAL_POWER=500.0*ONE_MILLIWATT

    if (flockOfBirdsDetected()) {
    setLaserOutputPower( MAX_POWER);
    wait(1);
    collectCookedDinner();
    setLaserOutputPower( NORMAL_POWER);
    }
  • Can a network take down a flock of birds flying through the lasers?

    I can see how this would interfere with RFC 1149 [rfc-editor.org]and RFC 2549 [rfc-editor.org] based networks. "War of the networks"? "Imminent death of the net predicted, film at 11"? It would take care of dinner nicely, though. Pass the cranberry sauce, please?

    Stefan.
    It takes a lot of brains to enjoy satire, humor and wit-

  • that article in forbes seems to have more real info than the company site itself. but they still dont mention the frequency the lasers use. they dont say anything about beam width etc. the guy who did the interview with forbes says he used "special glasses" to view the beam, which almost certainly means theyre using infrared which therefore means water (eyes for example) is going to appear opaque to the beam. now if the beam power is going to be continually adjusted for atmospheric conditions (btw. what about heavy snow?) im guessing its going to have to be fairly intense at times. i dont know if i trust their cheery "it's even safe to look in the beam" propaganda. they could've at least given the laser CDRH/ANSI classification somewhere on the site.

  • Solution to the bird problem. (Score:5)

    by Magus311X ( 5823 ) on Sunday August 20, 2000 @06:27PM (#840942)
    Can a flock of birds take down a network by flying through the lasers?

    Well, if you increase the power of the lasers, you could then only need to pose this question:

    Can a network take down a flock of birds flying through the lasers?

    Problem solved. ;)
  • Beware to the people that are interested in optical networking, unless you are so interested purely from a research standpoint. Optical Networking is the term to be talking if you are a Venture Capitalist these days. VCs are just pumping more and more money into any company that has optical networking in its business description. And, just as dot-coms had their flops, so will optical networking. Optical Networking stocks are also flying through the roof, just as dot-coms did a year or two ago. I'll be wary of optical networking for a good while until several leaders truly come out ahead of the pack.

    Optical Networking is ALREADY here. All the major network backbones run over fiber optics, hell even most cable companies have a hybrid fiber/coax network.

    Also, the leader HAS emerged, it is Nortel, they sell $10+ billion/year of optical networking gear.
  • With the recent Lucent record of over 3 Tbs transfer speed across 300 km using "classic" fiber optics channels (reported on slashdot earlier) I see less utility value in pursing wireless fiber optics channels. The decreased material costs of fiber will be more then likely offset by increased costs in power consumption, due to attenuation of the signal in water molecules and solid particles. I think wireless fiber still has more than a few years to mature.

    Firing lasers off through the sky is only a temporary solution. You will always get higher transfer rates using an actual fiber becuase it is such a better transmission medium. However, it is quite expensive to run fiber all over the place right now, as prices go down it will become more feasible and things like this will die off.
  • More power, Scotty! We need more power!
  • 780 nm
    http://www.airfiber.com/products/faq/Html/helpse t.HTM
    As for saftey if meets IEC Class 1 requirments.

    The FAQ seems very comprehensive.
  • Wireless broadband will no doubt be "the next big thing". I'm sure fibreless optical links will be great but I'm not convinced (yet) that they will be as big as some people are claiming. However, wireless radio broadband will certainly be huge.

    Wireless networks have several advantages over traditional land lines, especially in areas of rapid expansion. For one, the right of way issues are greatly reduced. It is a severe pain in the ass just filling out the forms to try to drag a cable across town, or across the state, or across several states. And it's not cheap either. The expense of actually laying the cable is also quite substantial. However, with wireless networks, you only need to setup a few base stations and boom, you've got a network.

    Pretty soon, everyone and their mother (literally!) will be wanting / needing broadband access, and right now a lot of people (and businesses!) just don't live where it's possible to get broadband any time soon. DSL is great, but the limited range means a lot of people are left out, and the limited speeds makes it unsuitable for a lot of uses. The best hope for most locations is a cable modem or getting their own line laid, cable connections are not particularly suited for high bandwidth serving or businesses, and paying for your own line to be laid is just murderous. On the other hand, if someone could just install a wireless connection with T1 -> OC1 (or faster) speeds with little delay they would make a lot of people very happy.

    Additionally, wireless networks are well suited to developing countries. There are lots of places on this Earth that lack even basic telephone service. By bringing wireless networks to these places, they can not only get phone service at much less the cost than they would be able to through more traditional setups, but they can actually get not too shabby connections to the wonderful world wide internet. In fact, many countries are deploying wireless telephone networks for precisely these reasons.

  • Well, look at it this way. Think about how long it takes to run a 30 mile fiber line.
    True, that does suck, and it's still pretty expensive.

    Now, think about how long it would take to run it wireless. Just point and shoot.
     Easier said than done. You'd need to calibrate the transmitting device to probably the nearest thousandth of a degree in each direction to be able to hit your receiver about, say, 1 mile away. (very crude, out-of-my-arse calculations.)
    The other issue is what might be in the way of the signal -- around Pittsburgh, for example, the terrain is rather hilly. It'd be hard to set up a link between downtown (even on top of the USX tower, ~850 feet high) and Greentree, only a mile or so away, as Mount Washington tends to get in the way. Not to mention what random building might pop up in between your two stations.

    Bringing something like cable or DSL into new areas would be quicker and cheaper. The labor costs for laying the line is much higher then a more expensive wireless system.
    True, in maybe the Midwest where there are no tall hills. Around here, we're stuck with the classic guided media, expensive as it might be.

  • I'll be wary of optical networking for a good while until several leaders truly come out ahead of the pack.

    Then Cisco will buy them and we'll all be back to the start.

  • Long, long ago I was at a science and engineering summer camp at Northwestern University and one of the project I built was a piezoelectric modulator for a laser beam that transmitted an audio signal across the room to a photocell that turned it back into an electrical signal. If you could do that with very little cost in parts (other than the laser, which was at that time a several hundred dollar device) 25 years ago, I'm actually surprised more "campus" networks are not glued together with laser beams instead of wire. Especially in commercial office complexes where companies move frequently and where new wire runs from building to building can be costly. Seems like it would be much easier and cheaper than microwave, and almost as reliable. Surely 100Mb optical modulators are not expensive these days.

    It would make for a nifty way for a few houses to share a broadband connection, too, if the cost is a problem.

  • Well,

    old radar used to be (still is?) microwave, so I've heard similar stories of foxes/cats coming to feed on the birds microwaved near commercial airports.

    However, given that the mast probably was metal, it probably would have been a bad idea to microwave it. (visions of tesla coil lightning bolts arcing from the mast...)

    I always thought big carriers should supplement their food by fishing. Does anyone know if they did this in the bad old days of sailing ships and salted meat?
  • sure, you have to use encryption, but you'd have to do that with an IR or even over the wire network too. A visible laser network is probably more secure than a bog-standard lan, as it brings security (visibly) to the foreground.

    Johan

  • OTOH, this may finally cure the pidgeon problem that most major cities seem to have.


    --
  • ... open up that data haven in Kinakuta I've been dreaming about all these years.

  • Glaring Technical Error (Score:4)

    by Chic Pea ( 153193 ) on Sunday August 20, 2000 @06:40PM (#840955)
    From the article:
    "And, with asynchronous transfer mode technology (ATM), the lasers have become intelligent enough to track the laser beams between the two optical transceivers, so they never get off target."

    How the heck is ATM going to keep the lasers on target? I think the author confused this with ATM signallig setting up SVC's on the fly to provide reliable data transfer through the network in the case of a link going down.
  • Fog that limits visibility to 10 meters? Where do you live?

    Come spend a spring in New Orleans or London. We get fog that, literally, limits all visibility to less than 2 meters. That means it's very hard to make out your hand held at arm length. Very scary stuff.

  • Weather susceptibility still a problem? (Score:5)

    by davidb54 ( 120923 ) on Sunday August 20, 2000 @07:28PM (#840957) Homepage
    This is an exciting technology, but there are some unfortunate tradeoffs which have to be made when trying to achieve ultra-broadband wireless in not-so-thin air.

    Bit rate is proportional to bandwidth times the logarithm of the signal-to-noise ratio. To maximize bandwidth, you go up to higher and higher transmission frequencies. To maximize signal to noise ratio, you step up the transmission power. But in a wireless laser network, both of these steps have their disadvantages.

    The first problem is essentially that the higher frequencies (e.g. infrared, which is on the order of microns, as opposed to microwave, which is on the order of centimeters) are more susceptible to various scattering phenomena. The most frequently mentioned is, of course, fog, dust, smog, etc. These scatterers are far to small to have any significant effect on, for example, cellular communications (transmitted signal has a wavelength of tens of centimeters, not microns), but they are excellent scatterers in smaller wavelengths. In addition, the atmosphere itself scatters visible light more and more effectively as you go to higher and higher frequencies, reaching a maximum somewhere in the ultraviolet. This is due to the electronic properties of diatomic nitrogen and oxygen and cannot be avoided. (As a side note, it is also why the sky is blue and sunsets are red). So, one cannot step around the fog problem by going to even higher frequencies. I believe, but am not certain, that fiberless lasers still operate in the IR.

    The second problem, of course, is that stepping up the power output of the transmitter is expensive. A tenfold increase in bandwidth requires a thousandfold increase in signal to noise ratio. To see why this is so, imagine that with a given signal to noise ratio, you can resolve 16 signal strengths with a bit error rate of less than, say, 10^-8. This means that you can transmit 4 bits of information per symbol. To get twice as many bits per symbol, or double the bit rate, you need to be able to resolve 256 signal strengths - i.e. square your signal to noise ratio. To get 12 (three times as many) bits per symbol, you need to cube your S/N, and so on. Essentially, you have to double your S/N for each additional bit per symbol you wish to be able to resolve at a certain bit error rate. Hence the need for enormously increased power to achieve relatively modest increases in bandwidth.

    So, with these constraints in mind, it will be interesting to see what optimum is achieved by TeraBeam et al, and how resilient their systems turn out to be.

    Dave Bailey

  • Unless there a method that uses radio waves I can't see how that would be a problem. If you are using on/off states in binary to transfer informaion all the receiver needs to know is wheather there is light or not at any given time. I don't get it.
  • Actually, in addition to increasing the power of the lasers, they should use the newly developed green diode lasers instead of the boring IR ones. If enough buildings used them, we would get to see a nice laser light show each night :)

  • What about fog? (Score:3)

    by Ibag ( 101144 ) on Sunday August 20, 2000 @06:50PM (#840960)
    An engineer sticks a thick piece of cardboard in front of the laser to simulate a sudden fog or a particularly pesky pigeon. Instead of losing data, R2-D2 senses a problem and automatically reroutes the information via another pathway--another R2-D2 unit with an unobstructed signal--so none of the data is lost.
    The only problem with this is that unless the R2-D2 units are large distances away from eachother, its very unlikely that fog will merely be between two units. A unit stuck in the middle of the fog will be completely surrounded on all sides, so communication will be shot between whoever uses the particular node and the rest of the world. Of course, depending upon how widespread this becomes, it is still possible that one can send a signal from one point that has no fog to another point that has no fog, but who is to say that on a heavily foggy day everybody who uses the system in a certain place will be without their precious network... I'd like to see what these things do when they are covered in a cardboard box!

    Ibag

    "Me fail english? That's unpossible!" --Ralph

  • Reminds me of the "ArcLight" (Score:4)

    by Ungrounded Lightning ( 62228 ) on Sunday August 20, 2000 @07:31PM (#840961) Journal
    This reminds me of something more than 20 years back: Datapoint's "ArcLight", for their Arcnet.

    Arcnet was a token-ring based network with a broadcast topology. Cut the connection between two parts and it immediately reconfigures into two nets. Plug it back in and it reconfigures into a single net.

    Ran on 8080-based terminals.

    To get between buildings they used a gadget with an infrared laser diode (which had just come out) and a photodiode - each behind a lens about 6 inches in diameter. The device looked somewat like a weatherproof half-height-full-width monitor case with a little bit of a lightshade and the screen replaced by a couple of big glass eyes.

    In a city where most buildings weren't skyscrapers (so a little defocussing could deal with building sway and clear-air turbulence without too much energy loss and interference acceptance), clouds and fog were rare, and at a time when high-speed data lines were 300 baud, it was great. A LAN that spanned multiple buildings. If the fog rolled in the network partitioned until it went away (no data between the head office and the branch for a couple hours, but the nets WITHIN the buildings were still up. Birds were handled by retransmissions that were part of the normal protocol.

    Something similar would be easy with IP these days: Run a low speed (56k, T1, whatever) between the buildings AND put up the high-speed link. On foggy days your bandwidth drops but your connection is still there. IP also understands flakey connections and rerouting around them, and TCP understands using retransmission to make a reliable connection over unreliable links.

  • Wow. (Score:3)

    by mindstrm ( 20013 ) on Sunday August 20, 2000 @07:44PM (#840962)
    It's amazing. Take a perfectly normal concept, like meshed networks, and apply it to wireless, and suddenly, you have made some kind of great advancement of science.

    I don't see how this is any different than normal problems. Ther are using a wireless PHI.. fine.

    The only point the article has made is that the price of optical open-air laser networking gear has come way down, so now it is feasible to build meshed networks with it, and hence, overcome some of the inherent problems with it.

    And if the equipment used to cost $150,000.. how much do you think the monthly rental for that DS3 cost anyway? Not cheap. It will quickly dwarf the cost of equipment.

    Of course, when we talk about canned networks for corporations (which *IS* a big deal these days), this gets more interesting.
  • prices will go down for the fibre it self but you'll still have right-of-way issues to deal with using any kind of land-line.
  • Well, look at it this way. Think about how long it takes to run a 30 mile fiber line.

    Now, think about how long it would take to run it wireless. Just point and shoot.

    Bringing something like cable or DSL into new areas would be quicker and cheaper. The labor costs for laying the line is much higher then a more expensive wireless system.


    until (succeed) try { again(); }

  • Can a flock of birds take down a network by flying through the lasers?

    Maybe they could adapt RFC 1149 - A Standard for the Transmission of IP Datagrams on Avian Carriers [isi.edu] and, instead of seeing the birds as a potential problem, use them as carriers. Sure, a device would have to print the scrolls of paper, and attach it to the birds. It would probably decrease bandwidth, as the mentioned RFC mentions: "Avian carriers can provide high delay, low throughput, and low altitude service.". It's worth a good read.

    To deal with this, they could also use RFC 2549 - IP over Avian Carriers with Quality of Service [isi.edu] .
  • Then for example you could connect to your linux server from your basement 100 stories underground when nuclear warheads are going off above you.

    Two small problems with that:
    1. Your Linux server had better be in a reinforced building strong enough to withstand a nuclear blast.
    2. Even if it was in such a building, the radiation from the nuclear blast would interfere with the wireless communication.

    In the interests of keeping this post on-topic, this is different from wireless/packet radio in that light and radio waves are two very different things. Light waves are on a *much* higher frequency, and as such aren't as prone to interference from man-made radiation (such as the nuclear blasts that sips brought up). But, the tradeoff is of course that there are line-of-sight issues.

    =================================
  • I just didn't have the time to read the whole /. article.

    But you had plenty of time to post and waste everyone else's time.
  • Maybe the can bundle the armed robot reported in slashdot last week, with the laser system, have it scan the sky, shooting down the birds before they get to the laser...oooops, that was a 747 not a goose.

    Going on means going far
  • ...wireless environment, which you should know if you care to crack open any introductory text on the subject (I prefer Stevens , TCP/IP Architecture Vol.2).

    Problems with signal degradation have already been solved. In fact, the U.S. military has been using wireless data communications for years. The speed isn't all there, but the basic problems have already been solved.
  • Hrm. Lasers are inherently polarised. How easy is it to switch that polarisation and to transmit (say) error correction in the polarisation, information in the carrier?
  • like can your lasers take down a flock of birds...
  • If you would have read the article it said
    Oh, in case you're with the Humane Society, even if a bird does fly through the laser, it doesn't come out looking like fried chicken; the lasers used wouldn't even hurt your eye, according to the AirFiber folks.
  • I wonder what birds flying through my data would look like? Fog I know, I see that all of the time.

  • In the article it spefically states that they can automatically increase the power of the laser in the case of fog. More laser power apparently cuts through the fog.

  • Too bad carrier pigeons are extinct.
    What a waste it is to lose one's mind. Or not to have a mind is being very wasteful. How true that is.
  • No, I didn't. I read the headline. I actually wanted to relate it to a National Geographic article but I didn't have time to write it down. It was in one this year where networks were being studied using wireless connections in large cities. They were looking at configurations regarding line of site. It was on the back page of the June 2000 issue. They use 3-D maps to help with the process. Here's [nationalgeographic.com] a link to the library article in the National Geographic site. I just didn't have the time to read the whole /. article. Sorry for the old mix up.

    Even the samurai
    have teddy bears,
    and even the teddy bears

  • A Flock of Seagulls [citysearch.com] has migrated through the lasers' paths!
  • Can a network take down a flock of birds flying through the lasers?

    Hey you might be on to something here.

    Get an optical wireless network, fly swatter, security system and anti-missle defence system all in one!

  • Re:What about fog? (Score:5)

    by Kris_J ( 10111 ) on Sunday August 20, 2000 @08:23PM (#840987) Homepage Journal
    A unit stuck in the middle of the fog will be completely surrounded on all sides, so communication will be shot between whoever uses the particular node and the rest of the world.
    Thank you, I thought exactly the same thing after reading the article. How does the system cope with fog?
    I'd like to see what these things do when they are covered in a cardboard box!
    Isolated from any control system they revert back to their basic programming -- kill all the humans. First they burn through the box, then they start killing anything moving...
  • Beware to the people that are interested in optical networking, unless you are so interested purely from a research standpoint.

    Optical Networking is the term to be talking if you are a Venture Capitalist these days. VCs are just pumping more and more money into any company that has optical networking in its business description. And, just as dot-coms had their flops, so will optical networking.

    Optical Networking stocks are also flying through the roof, just as dot-coms did a year or two ago.

    I'll be wary of optical networking for a good while until several leaders truly come out ahead of the pack.
  • Has anybody thought about the security issues?
    One of the advantadges to fiber is that it is incredibly difficult to tap, and the tap can be easily detected. Is the same true of wireless optical? And is tapping even relevant? I would assume that in the case of the Internet, you've got Carnivore tapping you, but otherwise fiber lines can pretty much be assumed secure. In the case of private networks, anyone with the budget for wireless optical could probably come up with a good encryption scheme. But is there anything I've missed here in the tapping issue?

  • Why "wireless fiber" (Score:3)

    by Ungrounded Lightning ( 62228 ) on Sunday August 20, 2000 @07:09PM (#841000) Journal
    The purchasers of bandwidth understand:

    - "Fiber" to mean very fast data sent via light (in something called "fibers" or "fiber optics" or something like that...)

    - "Wireless" to mean signals sent between two stations without any hardware spanning the distance. (Just install a box at each end and maybe an antennaish thing on the roof.)

    So "wireless fiber" produces the idea of sending high-speed data via light between two sites with gadgets on the roof without anything but open space in between them.

    Even if the words don't really make sense when you look at them closely.

  • Navy radar and mess deck food (Score:3)

    by A nonymous Coward ( 7548 ) on Sunday August 20, 2000 @09:15PM (#841008)
    25 years ago, the carrier I was on had a big honking radar. We used to hear scuttlebutt that the techs would get seagulls off the mast by mircowaving them. We figured it explained mystery meat and scab steak.

    --
  • I took his remark to mean that if there are lots and lots of R2-D2s around, instead of direct long distance links, you would reroute thru closer neighbors.

    Sort of like if long distance phone calls are out, you call Aunt Martha who calls cousin Bob and so on, each being a bit closer, until the final local call goes thru.

    I did something similar once, when home to work was not a local flat rate call. A friend in between, who was a local call to each place, installed an extra phone and set it up to call forward.

    --
  • Well it needs to be directional enough, so lasers will do. IR will penetrate fog and smoke alot easier than visual light as it is. Fire Fighters in big cities now have an IR camera they can take in with them into rooms pitch black with oily smoke, and they can search out victims and survivors just fine thank you. So IR is a distinct advantadge when it comes to smoke and fog.

  • Fog is a feature! (Score:3)

    by KFury ( 19522 ) on Sunday August 20, 2000 @06:01PM (#841012) Homepage
    "With new eFog, your point-to-point wireless optical data communications link can be enhanced into a local area network!"

    Next quarter, analysts forecast the public release of eClouds which will allow for a wide area network with a range of approximately 7 miles.

    Kevin Fox

  • OK, I must just be dumb or out of it, or something along that line. But, why do they call it wireless fiber? It doesn't make sense, a fiber is a solid object, a "wire" if you will. Wireless would imply that the "wire" does not exist. Why not just come up with a fun buzzword that actually makes sense?!?

  • Shannon's delight (Score:4)

    by XNormal ( 8617 ) on Sunday August 20, 2000 @10:14PM (#841030) Homepage
    Most of Dave's comments are relevant to RF communication, not to optical.

    Capacity is proportional to the logarithm of (1+signal to noise ratio). A small but significant difference. The result is that for a given power budget it is always better to use as much bandwidth as possible unless you are limited by arbitrary constraints such as the FCC's dumb frequency management practices.

    There's no need to go to higher optical frequencies to increase capacity. The carrier frequency of a 1.3 micron infrared laser is 230 terahertz. It's easy to see that a few hundreds of megabits per seconds barely scratch the theoretical capacity.

    You've got so much bandwidth in optical that more than one bit per symbol makes absolutely no sense. In fact, you want LESS than one information bit per symbol by using forward error correction codes.

    The right frequency to choose is in the atmospheric window wavelengths - those least absorbed by water vapor.

    In fog conditions the cumulative attenuation per meter is so high that even a hundredfold increase in laser power will not make a significant increase in the effective range. You are stuck with a few hundreds of meters. Deal with it. AirFiber's architecture looks like the right way to do it. Even if you ignore the bird problem, with a relay every few hundreds of meters the end-to-end reliability drops exponentially with the number of hops the signal has to go through. A mesh architecture can cover long distances while still maintaining adequate availability.

    ----
  • This wavelength is around the peak of the first Atmospheric window [ucsb.edu]. It's also cheap because it's the wavelength used by CD readers.

    ----

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