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Wireless 10 gigabits/sec data transfer 93

Posted by Hemos from the purty-please dept.
swedub writes "Lucent Technologies announced a breakthrough technology that eventually will enable business customers and service providers to transmit up to 10 gigabits per second (Gb/s) of information between locations through the air. " They are calling it WaveStar OpticAir. Global Crossing will be doing field testing this December already. This is the first system to actually use Bell Labs dense wave division multiplexing-can I get coverage in my area? But the encryption issues will be interesting, methinks.
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Wireless 10 gigabits/sec data transfer More

Wireless 10 gigabits/sec data transfer

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  • Re:SSH is a pain... :-( (Score:1)

    by Anonymous Coward
    Ssh is more of a pain than telnet because it is not preinstalled on your system. The reason it (or an equivalent program) is not installed by default is due vendors afraid of violating US export restrictions.

    Thus, the government effectively keeps strong encryption out of many US and non-US computers by increasing the pain in the butt factor. It's a clever and effective technique.

  • Re:That's Incredible!! (Score:1)

    by Anonymous Coward
    DWDM is in the visible spectrum, and the light is different colours, that's where the wavelength division multiplexing part of it comes in.

  • Wow.. brilliant technology. (Score:1)

    by Anonymous Coward
    sarcasm(on);

    Yeah, I heard theyre working on some strange new bizzare technology that will actually let you transmit an unlimited number of data streams in parallel over thin air.


    Theyre calling it something weird like "radio" I think.

    sarcasm(off);


    Bowie
    PROPAGANDA [themes.org]

  • Re:That's Incredible!! (Score:1)

    by Anonymous Coward
    Right on! I've been looking for a combo WAN / disco ball for years!

  • Weather (Score:1)

    by slew ( 2918 )
    Actually VERY large buildings like the boeing assembly plant actually have their own weather
    inside (fog, etc). I wonder if that means it won't work worth crap there either ;-)

    Optical isn't too different from microwave when it comes to weather problems (just ask anyone who
    owns a DSS system) and they seem to be pretty successful in an outdoor situation...
  • The idea is pretty cool, but if you are transmiting several differnt frequencies at once will you not also need several emiters for each frequency and what happens if one of them gets out of alignment.

    The other question is what pricing is going to be. I can guarentee its not going to be cheap since it is line of site only there will not be a HUGE demand for the things even though I can thing of a dozen or more aplications off the top of my head. Although its still got to be cheaper than digging a trench and laying fiber.

    Come to think of it with that much band width the television / movie bizz has got to be excited. This has got to be cheaper than a satalite uplink and if there is a remote even within the usable range of this tech all they have to do is set up and shoot the video down it.

    What is the efective range of this anyway?

    Well there are alot of questions on this tech. (others have posted the ones about weather ect.) but it does look promising and has more uses than I think most people are giving it credit for asuming it doesn't go down compleatly in a rainstorm.

    I'll be watching for more.
  • Since it's just a beam of light, how would this stand up to the rigors of use in space? Maybe to communicate between space stations, or a possible link between say, a space station and the moon. (Cloud cover on earth would probably make this unfeasable there) We're really not that far off from this.


  • What it sounds like is they found a way to achieve OC-768 over a laser. OC-768 comes to about 9.6Gbit/sec (I think), so my guess is the marketeers probably thought they would round the figures up to make it sound nice.

    There are several companies out there offering OC-3 and OC-12 over laser right now, so it isn't *too* much of a surprise that we now see this level of service. Think of SONET without the fiber...but remember it may be fast, but line-of-sight isn't always easy to achieve in even moderately crowded downtown areas.
  • You're right...you're right. OC-192 equivalent. Maybe it was just my wishful thinking. :) But still, I wonder what kinds of applications are going to be able to use this kind of bandwidth.

    I mean, the Abilene network is moving towards OC-48 on their backbone, and that will be shared by hundreds of universities, labs, etc. So basically, I'm not sure what the point is in point to point 10GBs...get my point?
  • Other systems I have seen like this fade out at 2 km and are useless in fog, snow, rain.... Anyone know any specifics about this one?

    I know there is one in production in Arizona somewhere.

    Joe
  • encryption not needed

    hahahahahahahahahahahaha...=)

  • Part of Harvard's internet connection comes via a microwave link from MIT. So whenever network performance is a little off, the hip thing to say is "Hmm, it's a little cloudy today..."
  • Put the laser receiver on the solid ground and run traditional line over the relatively short distance to and onboard the ship...
  • I don't think this sort of link is supposed to hook up a computer, but rather an entire site... 10gb/s is wasted on a single PC, workstation, or server... even a decently sized workgroup would waste the link...
  • Remember switching! bandwith seems to be getting easier all the time.

    of course, going through the air seems pretty cool, takes the fiber out of fiber optic and back into breakfast cereal... speaking of which
  • hrms... i'm using a microwave link now that sits on the roof and aims through the trees... encryption should be an non-issue as long as bandwith usage remains manageable; that is, the amount of bandwith the average user can use is close to what is reasonably encryptable using a lightweight scheme. Of course, snoopers would have to splice the actual laser... just keep a camera with really really big zoom along the path of the signal... hmm. so i guess i could upgrade my t1-ish (strange, 200 KBps (kbytes)downloads despite paying for 384 kbits microwave) to this in a couple weeks, cough. Ah. Anyone notice dem pitiable foo's in the article who confused bits and bytes? Phall to phoenish.
  • Why would any service provider use this? How many service providers have a direct connection to the other location, and what happens when a bird flys through the beam, or something else blocks it.
    Lucent should try making something usefull for a change. inferno and now this... they had so much potential


  • I wonder if this will drop out whenever it rains
    or snows like infrared Ethernet does?
  • cable modems in my area (central NJ) reportedly have downtimes of at least 15% averaged over a week. this seems ridiculous to me, but they're still selling like mad.
  • >Birds are not so much a problem because if it's
    >important, a TCP-like net connection is being
    >used, and retransmissions will occur. Now a whole
    >flock of birds, well...


    The solution is simple. Crank the transmit power up to a 20-30 watts or so. Any bird that flies through the beam likely won't do so again. Ever. 20-30 watts of laser radiation will probably also break through thick fog, and create an impressive light show people can admire. :) };)



  • Well, 10GB/s - 10% downtime avarages to 9GB/s. I'll settle for that! :-)
  • Well, in the press release, I didn't hear that they are wining about alignment: "bringing photons not only to the desktop, but to rooftops, windows and ships at sea"

    Also, it states the supported distance: A four-wavelength system with a maximum capacity of 10 Gb/s for distances up to five kilometers is expected to be commercially available in the summer of 2000. That's about three miles.

    By the way - this is an original company press release. Pretty much hyped, and still quite far in the future. Let's check back in one year and see what they actually delivery, and how big the market for that product will be...

  • It's a laser beam going from roof to roof. Eavesdroppers will have to intercept this beam. It's much easier to dig up a cable and tap that.
  • Since this is obviously not reliable as a constant link, would this technology be better suited as a package transmitter? ie. large amounts of info at one time.

    US Navy Subs only send/receive data at certain times. (when they are on the surface)

    Also, all Navy ships (or most anyway) have Stable Elements already, so adapting that signal to a tranceiver would be easy.

    It sounds like the private sector wouldn't benifit as greatly as the Military might. But you gotta admit, the thought of filling up your (present) Hard Drive in a sec or 2 is a pretty awesome concept!

  • These new, bigger, better, uncut devices are all very well but they do not meet a growing need: A WLAN device that costs the same as a modem.

    What we the people need is a WLAN device that can communicate with other WLAN devices in the neighbourhood, so making the internet more independent of local telecoms authorities. With parallel routing the bandwidth could be huge.

    It is still cheaper for me to buy 2 NE2000 clones and a 100m of cable than one single WLAN card. Until this changes we will never break the grip of the telcos, and will forever remain subject to the whims of the governments that they support.

    Vik :v)


  • No - not OC-768. What they have is 10Gbps which is OC-192.

    But - what they actualy have is 4 OC-48 links.
    Each OC-48 link is 2.5Gbps (really 2.488 - but close enough) and they use 4 different wavelengths of light.
  • Uh, I am pretty sure I have 128MB of RAM, not 16MB (128Mb).
  • Besides, infra red in the 1500nm range is affected to a lesser degree by fog and such, than light in the visual range.
  • Or more likely, active stabilisers driven from the gyro's in the ship's centre.
  • Hrm. I got the impression they are all pretty much neer the 1500nm range. Therefore, the spread due to differences in refraction are going to be pretty small.
  • I worked with a client who had 2 IR Wireless links (LACE - Laser Atmospheric Comm. Equipment ? ) installed. The systems were configured for T-1, although they could be used for Ethernet at 10Mbps. The path length was about 1/2 mile in each case. One link was pretty reliable, the other was quite troublesome. In the troublesome link, one end was mounted atop a chimney ( can you say wind? Sure! ) and the other was on a floating membrane roof. The links cost about $37K each, including the T-1 to Fiber converter and the mounting hardware. They were inconvienient to work with due to the mounting locations and hardware, and when aligning them, very minute adjustments of knurled-headed screws made significant changes in signal. The complete range of usefull adjustment was on the order of one rotation of the screw!

    I imagine that there are applications where these types of things are usefull, but the installation has to be rock-solid and well engineered.

    I think a better growth path is to install fiber. Lots of fiber. Everywhere. NOW !

    Z
  • Would I have to wear a tinfoil hat if I were standing in the datastream?
  • data cds are 650 megabytes... that extra 70 megabytes are used as a buffer. if you have a glitch in an audio cd, maybe you have an audible distortion in a song. if you have a glitch in a data cd, its all corrupted...


    ..................................@ @
  • With "spread spectrum" they mean that they are
    using multiple "colors" at the same time to create
    extra bandwidth. I don't think it has anything to
    do with using multiple transmitter-receiver pairs.
    Although it would be a good idea to provide
    redundancy.
  • Very high frequency - light (not visible I'm sure). Just think of it as fiber optics without the fiber, I suppose the same error-correction techniques would apply. Besides, with 10GB/s you have lots of room for redundancy.
  • DWDW is centered around 1550nm - in the infra-red region, but the main reason for that is that the fibre has a dip in its attenuation right about there (it can be engineered up and down a bit but its centered around 1550). However since there not using fibre they may have decided to go with some other freqs... That said with the amount of money invested in infra-red comms lasers its doubtful theyve switched to something totally different.
  • "Lasers are directed ... "

    Well, my Ham Radio experience tells me that radio is VERY directional, especially at high frequencies! Ever hear of EME bouncing? Basically, ya take a very short wavelength (in the low digit Gigaherz range) Yagi antenna, aim it at the moon and it maybe bounces back somewhere here on earth. I've been in the presence of conversations with folks from Agentina... all via radio waves bouncing off the moon.

    Mike
  • This technology is not intended for ISP use. If you read the article, the suggested uses are things like corporate campus networks and special events requiring high bandwidth. You don't get one to your house. You get one between your two great big office buildings or the two ends of your college campus, or you set one of these up at a big conference.
  • I doubt that this will become very popular. I work for a small ISP and can say that this just wouldn't be financialy feasable. Plus, the weather here sucks eight months out of the year. Another factor that people haven't mentioned is what about a nice wind storm? Or bandwidth on the internet to begin with? DSL is already causing a slight slowdown as it is, this would bring it to its knees if it were to be popular. I'm beginning to think that Lucent is full of crap between the ears (IMHO).
  • they mention DWDM which stands for dense wavelength division multiplexing... in escence they are using many different eavelengths... and they are probably IR ....
  • The main reason this system is better than RF is because it has much higher capacity... The fastest LMDS radios today can do 155 Mbps while this can do 10 Gbps. So there's an obvious advantage. Another advantage is licensing. microwave radios require licenses to operate, this does not. Those licenses have to be paid regularly too... and they are getting expensive.
  • that's actually called scintillation and does have a dramatic effect on performance. However, by installing them properly and with proper design, one can reduce the effects.

  • Vaporware (Score:2)

    by Anonymous Coward
    Maybe there should be a vaporware category. Please don't take my post as a flame or flamebait, but I am starting to get tired of stories like [company] discovers/invents a new process/technology that may become useful sometime between 1 and 10 years. I just find information that is relevant today to be so much more useful, if there was a vaporware category then I can consider it as such. The same thing goes for game sites that write article after article of previews and rumors and interviews about games that aren't out yet. I guess I prefer to live in the now. I'm just too impatient to constantly be looking forward to the next big thing.
  • >Also, what kind of redundancy does this thing
    >offer? What if something passes in between the
    >receiver and transmitter, or the weather is bad?

    If a cd-rom doesn't make it, you just walk over, pick it up, and throw it again.

  • One of the first things that I learned about when I was studying the physical layer in network communications were protocols using this type of medium for physical transport. The author of the text (Andrew Tanenbaum, the author of Minix) criticized it for its easy disruption by weather/obstruction/heat. Something that many people seem to fail to consider with this is the refractive qualities of air - although they see the obvious, such as birds and other foreign object flying through the paths of the beams(something the is quite likely to be corrected for in the protocol; any good data protocol will incorporate error correction/detection featers so these types of incidents are made quite irrelevant), they don't seem to see that if there is a substantial difference in the heat between the two points, the air will be different enough to refract the light so it misses the transceiver entirely. Again, if the protocol designers have a clue, they might incorporate some sort of detection/correction (in this case, possibly moving motors in the transceiver to correct for the refraction). Just my two cents worth on this protocol.
  • It's a laser beam going from roof to roof. Eavesdroppers will have to intercept this beam. It's much easier to dig up a cable and tap that.


    Not really. If there is dust, smog, or rain in the air, a fair amount of the light will scatter. With proper equipment, it wouldn't be too hard to tap the beam.

  • A fair amount of light ? How about a few photons here and there. Any light that is disspersed will go in all directions. Trying to intercept such scattered light and properly demodulating and demultiplexing it would be extremely difficult without even considering encryption.


    Ever go to an outdoor laser show? What you're seeing there _is_ scattered light, without the benefit of smoke generators.


    The light is also being transmitted at a very specific, known frequency. Put a good quality filter on the tapper, and your signal-to-noise ratio improves considerably.


    Want more signal? Place your receiver so that it's as close as it can be to looking down the beam.


    You can't do laser communications over miles with a laser pointer. There is a very bright laser producing the beam, and a fair amonut of scattering.

  • From the article:
    "At this rate, customers will be able to transmit the data contained on 15 CD ROMs through the air in less than a second."

    CD capacity is ~600M, right? 15*600 is 9000, or 9G. Isn't 10Gbps, ~1Gbyte/s? Did they confuse GBit and GByte?

    On the other hand, either way it's faster than PCI, so I won't be using up all that bandwidth by myself...
  • A lot of people pointed out that weather can and will mess up an outdoor laser-based network. Given that, I assume that most of the uses for this will be indoors. Think manufacturing plants (Boeing, Ford), conference/concert halls, trading floors, etc. It makes a lot of sense if you want a high-bandwidth rapid-deployment network inside a building with appropriate lines-of-sight. Much easier to install/uninstall than draping cable over or under everything, especially if you need this network for only a few days/weeks.

    Kaa
  • a) Bad weather? Falling rain/snow, fog, dust clouds, tree leaves, a bird... Poof. Terrible reception.

    b) Not mobile? One of the big things that radio networks are good for is allowing laptop users to move through the areas of service. Lasers are directed ...

    c) Useless for people needing the high speed link - see a

    The way I see this technology working isn't too impressive. It seems to me that it would just link directly into a more conventional network for temporary use when the weather is known (or projected) to be good... The conventional net would then be divided among a large number of users... The distances it carries data can't be great, because as distance increases, the likelihood of an interruption also increases. Also, even tightly focused laser beams become diffuse eventually...
    From the way the article presented it, it seems like there would be multiple nodes each feeding data to the next... but then you have to have permission to put a node down on property that you don't own...
    The only real use I see for this is for very short term things where laying the lines is too much hassle and 100% uptime isn't particularly important... ie. conferences, expos, etc...
  • It seems every time I see an article on Slashdot about some new way of laying out networks or how netwoking is changing, the author seems to make an small snide comment about encryption. Look, the fact is that we have solved this problem with IPsec and other tools such as ssh. Who cares if everyone is able to read my traffic, for I am using end-to-end encryption with all hosts that I frequent and send sensitive data to?! As machines capable of using IPsec become more prevelant (and they will now that Windows users finally got their own decent IPsec implementation through PGPnet), these comments will become more and more disinformative.

    I guess what I'm trying to say is that these comments are just going to contribute to FUD. The tools to be secure are out there. Use them, for goodness sake.
  • A DS3 (About 44 Mbps, or 5.5 MByte/sec) runs about $1500 PER MONTH. This gadget is the bandwidth of about 227 of them. The equivalent of 100 times the bandwidth of a 100Mbps ethernet, vs a T3 which is a bit less than half of one.

    If it costs a few grand per box, one-time, a company with two or more buildings within line-of-sight of each other but not on contiguous land, in a region with even moderately good weather, might buy them to connect the building LANs, and fall back to a puny T1 (1.5 Mbps) on stormy days. BIG bargain.

  • "I work for a small ISP and can say that this just wouldn't be financialy feasable."

    Technology like this will eventually crush small ISPs. There is a huge economy of scale in the high-bandwidth ISP business that small ISPs will never achieve. Small ISPs are pretty small much fish in the evaporating modem pool.

    Actually, methinks something like this could mutate and eventually kill ISPs altogether because the transport medium is free and unregulated.

    If you get enough computer geeks with [quasi-directional] roof-top stations with/and/or localized radio LANs then you could eventually bridge the entire continent on a sub-Internet.

    In a perfect fantastic world every building would just be a relaying node one big spanking public network. (Maybe free networking will become the next electric car -- suppressed but it will happen eventually.)

    There would be all sorts of neat-o architecture problems too. Fun stuff for the network-design masochist and the script kiddie alike.

  • The article doesn't say how the bandwidth will fair during bad weather, ie rain storms or blizzards. Methinks this will go the way of personal satellite uplinks - very specialized applications where reliability is less important than cost, speed, etc. 10GB/s is nice, but if it has 10% downtime whats the point?
  • 650MB*15 per sec = 9750MBps = 9.52GBps
    (Mbytes) (MBytes) (GBytes)

    ... yeah, but 9.52GBps does not equal 9.52Gbps
    (GigaBytes) (Gigabits)

    The original poster is correct, somebody is fibbing at Lucent. To transfter 1 MB at 1 Mbps, it would take 8 seconds to transfer.

    This is all due to communications using standards in "bits per second" (see: Old Hayes Modems) with
    PC's use of bytes (see: To sell more computers, PC makers say RAM is 64 MB when it's really 64 Mb).

    Rick

  • Dense wave division multiplexing (Score:3)

    by Omnibus ( 1831 ) on Wednesday July 14, 1999 @10:37AM (#1802679)
    GTE/BBN uses dense wave division multiplexing in their new GNI (Global Network Infrastructure). They got some nice OC192(10gbit) running all over (17,000 miles worth) and is already operational in several major markets. Lucent may be the first to use it wireless, but not the first to ever use it.

    asinus sum et eo superbio

  • The idea is pretty cool, but if you are transmiting several differnt frequencies at once will you not also need several emiters for each frequency and what happens if one of them gets out of alignment.


    That depends on the modulation and mixing schemes that they use. By the time the carrier reaches the output, it's been multiplexed on to one beam, so lining up several emitters shouldn't be necessary.


    OTOH, the transmitting and receiving mirrors will have to be aligned very precisely. There are a few ways to do this (even ways to do this automatically). Solving this is picky but not intrinsically difficult.


    Come to think of it with that much band width the television / movie bizz has got to be excited. This has got to be cheaper than a satalite uplink and if there is a remote even within the usable range of this tech all they have to do is set up and shoot the video down it.


    It would probably wind up being more expensive than satellite for TV broadcasting, actually, because TV is _broadcasting_ - using one (espensive) satellite to send data to many, many homes. The cost of the satellite is amortized over the number of viewers that it serves. A laser link, OTOH, only serves one user.


    Where it would be more useful is in transmission of TV data from the master station to other distributing stations, but they already have microwave links in place for this (that's what all of those towers in the countryside with dishes and ariels on them do, among other things). Lasers would give higher bandwidth, but how many cable channels do they want to transmit?


    What is the efective range of this anyway?


    That depends on several things, but a previous poster said single-digit kilometres (or miles, if you prefer). This sounds reasonable. Haze in the air will scatter the beam after a while even in clear weather.

  • 10 Gb, cool but limited (Score:3)

    by jabber ( 13196 ) on Wednesday July 14, 1999 @09:22AM (#1802681) Homepage
    As another poster already noted, it's 10Gb weather permitting.

    Also, it's a line-of-sight technology. I, for one, can't imagine this being used effectively for much more than spanning roadways and other public right-of-way restrictions without the legal hassle of an easement. Maybe jumping over a small river or such, but the morning fog, or the heat rising off the rooftops would just shoot your network to hell... ;)

    Cost-wise, I doubt that this will ever be more affordable than traditional fiber. The endpoint hardware has to be at least as expensive, and the cost of fiber vs. the power needed to push light through the air is a major argument in favor of glass/plastic.

    My 0.02 euro

  • yeah right. (Score:3)

    by Skinka ( 15767 ) on Wednesday July 14, 1999 @09:57AM (#1802682)
    ping slashdot.org
    >Request timed out.
    >Request timed out.
    >Request timed out.
    >Request timed out.

    "Oh shit, it's raining again!"

  • Really need to know the link budget (Score:3)

    by Zoinks ( 20480 ) on Wednesday July 14, 1999 @10:23AM (#1802683)
    1) With regard to link reliability, we really need to see the link budget and the % availability they expect to achieve at 5 km. And just because it's raining, snowing or foggy doesn't mean the system is useless. Attenuation is not binary, and athough the link may go away at 5 km, it still may be useful at 500 m, because there's 20 dB more power in the link budget. I can imagine a semi-permanent link between buildings in NYC, for instance, that would expect and get 99.9% availability with this sort of link, and that might be just fine.

    Birds are not so much a problem because if it's important, a TCP-like net connection is being used, and retransmissions will occur. Now a whole flock of birds, well...

    2) Encryption? Well, it is hard to intercept because you'd have to be in the line-of-sight. Now if you're between the Tx and Rx, you'd probably have a good intercept, but you might ruin the link for the legit user. If you were behind the legit Rx, then that receiver would be blocking you, and you as well might be out of range for the link.

    Still, if it's important, the user(s) that need encryption will do so as necessary on their connection(s) only.

    3) No good for anything but line-of-sight (LOS)? This is still a big market for data carriers. There's bandwidth all over the place between 2 GHz up to 38 GHz for point-to-point use, and these pretty much have to be LOS-only. At around 28 GHz, there's LMDS, which is point-to-multipoint; still, it's LOS-only (in spite of what some might say).

    This laser solution is clearly LOS-only, and will require proper aiming and all that at each end. And, it isn't very mobile, but Navy ships could certainly afford the required autotrack mechanism to make this useful even with gentle rocking of the ship.

    Yes, I do this for a living, only at RF.

  • Possible applications (Score:3)

    by Doco ( 53938 ) <Dan@@@oelke...com> on Wednesday July 14, 1999 @09:50AM (#1802684)
    Anyone who has used a line-of-sight optical system for doing a T1 or something similar knows that this won't work worth crap in a lot of typical outdoor situations.

    I see a couple of good applications.

    1) Get the bandwidth up today while you get the trencher out to bury your fiber.

    2) Replace the bandwidth today after somebody else cut through your cable trenching in their fiber ;-)

    3) Use it indoors. Large convention centers could use a couple of these puppies to move lots of data around where fiber runs might not be pratical. Also think of Boeing's assembly plant. VERY large building with pretty decent sight lines without weather problems.

    In general though - this is only going to be useful to a far smaller number of people than would use a traditional fibered system.

  • Visible Microwave (Score:4)

    by pspeed ( 12169 ) on Wednesday July 14, 1999 @10:07AM (#1802685)
    Ok, I'm going to geek out here for a second...

    It sounds like they intend to use this like point to point microwave, but in areas where microwave isn't feasible. This is becoming more and more of an issue with wireless local loop technology being the current vogue.

    The problems with microwaves is that they scatter. Not only do you have to worry about the beam getting to the other end but you also have to worry about all of the reflected signal that will interfere with both ends and any other microwave sites. Plus there is the bleeding of signal out the back... the antenna patterns can be fairly complex and interference analysis is a very big business. Some would argue that the wireless local loop and point to multi-point markets have yet to be adequately addressed. The engineering can get very complicated. Especially if you are talking about small-scale dense areas like campuses and office complexes.

    Also, the equipment for microwave is likely to be more of a hassle. If you aren't familiar with it there is a lot more to it than you might think. Compressors to keep the waveguides empty, etc.. (Fiber makes a pretty good waveguide for light. :) )

    re: Weather. Light is highly attenuated by water droplets in the air but so are microwaves. This is all part of current reliability analysis when designing microwave links. There are known ways of limiting the affects of this and they might apply to light as well.

    It would be interesting to have a reliability/attenuation comparison between microwave beams and light. If only I were a microwave engineer instead of the guy that writes some of their software... I might have more to say.

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