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1Gbps Optical Wireless Network Might Replace Wi-Fi 200

Mark.JUK writes "Pennsylvania State University has developed a new method of indoor Optical Wireless network that does not require a line-of-sight and runs at speeds of 1Gbps+. The system uses a high-powered laser diode — a device that converts electricity into light — as the optical transmitter and an avalanche photo diode — a device that converts light to electricity — as the receiver. The light bounces off the walls and is picked up by the receiver. Traditional radio frequency systems (Wi-Fi , WiMAX etc.) do not require line of sight transmission, but can pass through some substances and so present a security problem. Light, in a room without windows, will not escape the room, improving security."
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1Gbps Optical Wireless Network Might Replace Wi-Fi

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  • by weirdcrashingnoises ( 1151951 ) on Saturday January 30, 2010 @02:22PM (#30964580) Journal

    it's interrupting my downloads!

  • by ClosedSource ( 238333 ) on Saturday January 30, 2010 @02:23PM (#30964588)

    This is only going to work in the small area that the laser can get to, so cables might be a better solution.

    • If you considered this an open-air fiber optic cable (minus the fiber and the cable) then there may be a cost benefit over cables. Each cable requires infrastruction from jacks, in-wall cables, switch ports, etc while a whole room optical wireless could use a single switch port. Also consider that the price of these components could be very low. Diodes are typically not very expensive and a diode->serial USB could be made very cheaply though would not be gigabit speeds.

      I think that for basic connectiv

    • If the hand-off is fast then it could be good. You'll need a base station in each room, but at that speed you can just mount them on door frames with an endpoint in each room and they can relay between the rooms.
    • Get ready to buy telescopes to steal neighbor's internet!!!!

    • Re: (Score:3, Insightful)

      by hedwards ( 940851 )
      It depends what you're wanting it for. This has tremendous potential in areas like NY City and Tokyo where there's enough population density that traditional wireless is hard to do. Even here in a relatively sparsely populated part of Seattle, there's something like 8 access points in use at most times. The added security would be a bonus, just pull down black out curtains when you want to block it completely rather than mostly.

      But you still get the mobility to move around the room. I suppose in the futu
    • Point to point (Score:2, Interesting)

      by symbolset ( 646467 )

      It's a laser so the beam can be tight. That lends itself to geeking it to reflective targets mutually visible in outdoor applications. If people can get wifi at 237 miles [engadget.com], this tech may be capable of extending both the range and bandwidth of point to point communications. That would extend the reach of the Internet to a lot of people isolated by distance and infrastructure. That would be cool.

      And then there's the neighborhood network thing. I can gather maybe 250 single family homes into a network wit

  • by aBaldrich ( 1692238 ) on Saturday January 30, 2010 @02:25PM (#30964606)
    I like to shut the door of my room while watching my movies and other stuff.
  • Headaches... (Score:3, Insightful)

    by venkateshkumar99 ( 791435 ) on Saturday January 30, 2010 @02:26PM (#30964612)
    If the LASER is anywhere in the visual spectrum, the whole house could become a perpetual disco ;)
    • or seizure generator!

      • Re: (Score:3, Funny)

        by darkpixel2k ( 623900 )

        or seizure generator!

        Only if you use bittorrent...

      • Re: (Score:3, Interesting)

        by sillybilly ( 668960 )
        Persistence of vision kicks in above 25 Hz, and some people can still sense an 85-100 Hz refresh on CRT monitors with their periferal vision, but anything vibrating at a higher frequency is oblivious to the eyes. I'm guessing stuff transmitting in the GBit/s range is operating near 1GHz or close to it, which is well above the 100 Hz flicker you can see. If anything, the laser hitting you in the eyes, especially if it's infrared and invisible, might be the problem.
        One of the issues becomes the data interfer
        • That brings the question to mind as to why regular wifi does not suffer from multipath reflection? It probably does.
    • by Shatrat ( 855151 )
      It won't be. It will either be 1310nm or 1550nm.
      I doubt that anything lower than 1310 would be used due to increased attenuation of higher frequencies.
      By the way 1310 is more than double the wavelength that you can see with your eyes, and if this thing is made with APD receivers then it will not be cheap.
      • ...if this thing is made with APD receivers then it will not be cheap.

        No technology is cheap when it's first mass produced. I came across a Computer Shopper from 1990 awhile back, 286 systems for $2000!

        • by Shatrat ( 855151 )
          APDs have been mass produced in large volume for at least a decade for telecom. They are still much more expensive than a PIN style detector.
          Unlike the PIN they have a feedback loop to shut off or reset the detector after each bit since each bit detected creates an avalanche of stimulated emission. They're pretty complex tiny little thingies which require exotic materials.
        • by Mr2001 ( 90979 )

          No technology is cheap when it's first mass produced. I came across a Computer Shopper from 1990 awhile back, 286 systems for $2000!

          Indeed, these days you can get a 286 system for almost 50% less! [ebay.com]

      • by Hadlock ( 143607 )

        Why wouldn't you use something in the visible spectrum? It seems that red lasers would work equally well. red lasers are insanely cheap (petco: $2.99, probably $0.30 in bulk). There's not really anything stopping someone from developing this sort of thing using red lasers and some sort of receiving eye. It's already been proven that you could intercept someone's network information by reading the data off of someone's network card TX LED. I don't know about the lifespan of 5w green lasers, but I bet homebre

        • Re: (Score:3, Interesting)

          by Shatrat ( 855151 )
          I'm going on what I know about fiber, but I assume the same holds true for air but with higher values of attenuation and maybe a shift up or down in frequency.
          Basically at frequencies of 1310 nanometers and lower your attenuation is mainly due to scattering.
          Your photon will scatter off any imperfection in the medium larger than it's wavelength so short wavelengths scatter a lot. This continues in fiber up to around 1600 NM where the main cause of attenuation becomes absorbtion of the photon by the atoms it
  • by Oxford_Comma_Lover ( 1679530 ) on Saturday January 30, 2010 @02:26PM (#30964620)

    > Light, in a room without windows, will not escape the room, improving security.

    Although at a cost? This system might be useful for Universities that need to provide wireless to a hundred computers in the same room, but it would be almost useless for homes and such, where one of the big reasons to go wireless is to avoid the need to rewire the house. To use a 1 Gbps signal, you'd need a hard-line to the room.

    The other point is that for most applications, it's simply unnecessary to improve over the speed of modern wireless.

    Still, there are a few niches where this would be useful, and it sounds like a really fun idea to develop.

    • Still, there are a few niches where this would be useful, and it sounds like a really fun idea to develop

      I've been trying to think of the niches, and the obvious one is in security applications, but I don't see that as being any more secure than encrypted wireless. Is there really a use for this? Nice to know it's possible, I guess.

    • Wrong on one count (Score:4, Insightful)

      by dreamchaser ( 49529 ) on Saturday January 30, 2010 @02:41PM (#30964746) Homepage Journal

      The other point is that for most applications, it's simply unnecessary to improve over the speed of modern wireless.

      Uh huh, and 640K should be enough for anyone, and there's no reason to go to broadband when a regular old analog modem is sufficient for most applications, and...well you probably get my point by now.

      • Re: (Score:3, Insightful)

        ...And does anyone ever get internet connections even -close- to the 54 MB/Sec of wireless G? If you are streaming media throughout a home its nice, but most people don't use their wi-fi for that, they use it for internet where the primary bottleneck is the internet service, not the wireless router.
        • I use my Wi-Fi for that. If it's late, and I'm tired, I'll watch a movie on my laptop off my NAS, so then I can just close the laptop when I'm finally tired enough to drop off.

          However, that means this new optical wireless is useless to me. The only application for home use I could see is keeping multiple devices connected to some data server in a home theatre set up, to minimize cables. I think this is something not even for enthusiasts, but for very specific situations, so Wi-Fi isn't going to be "replaced

        • I use wifi for multiple devices on my internal LAN; I wasn't even thinking about Internet. As for bandwidth, I get about 30 mb/sec now and I'm sure that will just keep increasing as well.

          My point was there's no such thing as a technology that should not be improved upon for future needs.

          • LAN is always internal, it is called Local Area Network afterall ;)

            and i doubt you are getting 30mb/sec on wireless, more like 30Mbps, and not 300Mbps ;) In my experience, wireless is very unreliable, i don't use it even for LAN due to unreliability and slow speeds. At our office, people using WIFI, when they complain about slow internet access or local dev server not working, or other wierd network problems, it's 100.0% of the time about the wireless. And we use highend hardware for that (good enough for i

        • ...And does anyone ever get internet connections even -close- to the 54 MB/Sec of wireless G?

          That's megabits, not megabytes. And no, you usually get perhaps half of the stated maximum speed with wireless, for wireless G that means ~25 Mbit/s, or ~3M/s, at best.

          • by dgatwood ( 11270 )

            Either way, IIRC, the average broadband speed is still single-digit Mbps. So for most of us, Wi-Fi can still trivially saturate our upstream link.

            • Whoops, not here in Chicago (not exactly a small market). Comcast offers 100Mb/s down, 30Mb/s up (burst). More than enough to saturate all but the most stable 54g network.

          • And no, you usually get perhaps half of the stated maximum speed with wireless,

            So switch to wireless n - I transferred 100 gigabytes from my laptop 2 days ago (cleaning up the laptop) and I got the full 100mb/s speed - and that's over a 3-year-old dlink b/g/n I picked up on sale for $50.00. I seriously doubt that anyone was out there trying to crack the encryption, and if they were, I could have always used ssh.

            If you're only getting half-speed, try switching channels. Also, n is a lot better at rejec

            • I'm not interested in downgrading to wireless n. I'm quite happy with gigabit ethernet with which I actually get the full gigabit of wire speed.

        • and does anyone ever get anything even -close- to the 54MB/Sec of what wireless can do? ;)

          Btw, 48Mbps connections are available widely in Finland now. And don't get me even started with Sweden or Japan ...

      • Re: (Score:3, Interesting)

        by TheRaven64 ( 641858 )

        640KB is enough for some people. 6.4MB is enough for a few more, 64MB for a lot more, 640MB for a lot of people. Each increment increases the things you can do. 64KB is enough for editing text. 640KB for rich text and small images. 6.4MB for larger images. 64MB for large raw images. 640MB for SD video. 6.4GB for HD video. 64GB for volumetric 3D images (the visible human dataset is around 40GB). 640GB for volumetric 3D movies. Are there things that 640GB isn't enough for? Almost certainly, but th

        • by selven ( 1556643 )

          Back in 2000, 64 MB was the limit. Many people wanted to edit text and rich text, many people wanted to edit images, few people wanted to edit large raw images. Very few people cared about movies stored on a computer. From that mindset, adding more MB seemed useless. Now, in 2010, the limit got pushed up, with many people editing images, many people having movies and very few people having volumetric 3D movies. Adding GB seems pointless, but if we go up to 6.4 TB, people will start storing full high-definit

    • If you have more than one computer, and that would be the sort of situation that this is targeted at (if you have only one you probalby have your cable modem plugged right in to it) 1gbps lets you transfer quickly between them. With 100mbps or lower, your limit is the network. Anything over the network is noticeably slower than something on your computer. Things can take a long time to transfer. However with 1gbps, the limitation is often as not something in your computer like the harddrive. Speeds over the

      • With 100mbps or lower, your limit is the network

        No it's not. Use a switch, not a dumb router. A switch will recognize the source and destination address, so it's 100 mbps between any two ports. Even el-cheapo switches have a 4k-entry lookup table nowadays.

        Now it's true that wireless n, you're limited to 100mbps per channel (and you can actually achieve this). There's nothing to stop you from running 3 or 4 wireless routers on different channels in the same area, each connected directly to a different

    • I don't particularly see the usefulness of this tech for single-room "computer labs" - running cable is not difficult and will almost certainly be far cheaper. Also, you're not really all that concerned with the visual appearance of cables in a computer lab.

      Not to mention that (based on my group's experience anyway) university computer labs tend to be theft magnets, so you'd have the issue with people wanting to walk off with your optical router and/or the optical receivers.

      As far as security goes... all of our computer labs have windows, so the signal wouldn't be confined to the room anyway.

    • by Flwyd ( 607088 )

      Also conferences with a could hundred livebloggers in an auditorium.

    • The other point is that for most applications, it's simply unnecessary to improve over the speed of modern wireless.

      There's still video. IIRC, uncompressed 1080p/60 is roughly 3Gbps. Now you can still stream video without hitting 3Gbps, but then you theoretically lose quality and also you need more power to decompress the video stream on the other end.

      Even ignoring the aspect of real-time streaming, people are buying/storing video at home, which even highly compressed can be several hundred megabytes per hour; if you want to copy those video files from one computer to another, you'll want some speed.

    • The other point is that for most applications, it's simply unnecessary to improve over the speed of modern wireless.

      Of course, also 640K ought to be enough for anybody!

  • It's only more secure if it implements the same security measures (encryption, key based access) as current wireless (okay, if the light is infrared it may be stopped by windows.

    I don't think it will be a big contender for wireless though. The killer feature of wireless is that you don't have to drill holes in your walls to have network connectivity in the entire house. But if the network is optical, it will essentially be limited to the room where the base station is. Personally, I'd stick to my trusty
  • security (Score:4, Insightful)

    by wizardforce ( 1005805 ) on Saturday January 30, 2010 @02:33PM (#30964674) Journal

    How many homes don't have windows? Of those homes, how often is it that there is a need to connect with a computer inside a closed room? Any system that can connect to a computer inside a closed room can also be connected to from outside the house. Any system that can't be connected to from outside the house also can not connect to a system with the door shut. The number of times the signal can bounce off walls would significantly affect the range of the system. So while a direct path between floors of a house may be 10 meters, the path through the house from the top floor going around everything that is opaque to the system might be 50-60 meters and quite possibly out of range.

    • by imroy ( 755 )

      How many homes don't have windows?

      I may be wrong on this, but I seem to remember our Australian building code requiring a minimum amount of ventilation for any room that will be occupied by people, and the same may apply in other countries. So you have a few options - usually a window or an exhaust fan. People tend to favour windows (note the lower case 'w'). So I'm guessing there aren't many rooms in homes that don't have windows (again, lower case 'w'), for strictly legal reasons.

  • Naturally (Score:5, Funny)

    by Junta ( 36770 ) on Saturday January 30, 2010 @02:33PM (#30964678)

    Light, in a room without windows, will not escape the room, improving security.

    As usual, Windows makes networking less secure, why am I not surprised.

  • For awesome dance club effects.
  • by Arancaytar ( 966377 ) <arancaytar.ilyaran@gmail.com> on Saturday January 30, 2010 @02:40PM (#30964728) Homepage

    Light, in a room without windows, will not escape the room, improving security."

    Well duh, everyone knows that avoiding Windows improves your security.

    • I was going to say, preventing outdoor light from entering the room is just another way of getting security through obscurity! We all knew in the back of our minds why working in dark basements was a good idea...

  • by Animats ( 122034 ) on Saturday January 30, 2010 @02:46PM (#30964790) Homepage

    IR office networks were popular around 15 years ago. HP used to have a "NetBeame" IR access point product line. (There's one on eBay for $49. [ebay.com]) There's Linux support for IRNet. The Infrared Data Association is already promoting gigabit IrDA.

    The concept of diffuse IR networking works fine, but it never really caught on. You can usually get a signal with one bounce, typically off the ceiling, but more than one bounce and it tends not to work. You don't get any useful diffraction around obstacles at IR frequencies, so shadows are a problem. If you populate the ceiling with little IR domes, it works fine, and I've seen that done, but it's obsolete technology now.

    • You have may be able to modify it for cheap gigabit line of sight. Which isn't an obsolete technology.

       

    • The opposite of this has actually been used with casinos and hospitals for tracking things in rooms. Employees and/or patients wear IR transmitting badges or wristbands that transmit a burst every so often, which are picked up by receivers in every room. It's a simple method for tracking people's movements over time. It's a good way to find out about employee theft in a casino. Also, for example, they would place wristband transmitters around an infant's wrist. If someone tried to cut off the band (so

      • Also, for example, they would place wristband transmitters around an infant's wrist. If someone tried to cut off the band (so as to kidnap the infant) it would immediately begin transmitting at max power, alerting the staff.

        1. Cut of the kids hand. Nothing says you're a serious kidnapper more than a severed body part.
        2. Tin foil. It's not just to keep Bill Gates from reading your brain waves any more.
        3. Cut off one kid's band and toss it out the window - in the confusion nobody will notice you swiping a differe
  • I smell a grant proposal
    I think that they just strung together hot buzz words, Mad-Libs style
    Wireless optical? what could be the problem with that?
    I have a cordless monitor that I'd like to tell you about too...

  • Which makes its mostly useless for 99% of us, unless you run cables to repeaters everywhere, which sort of defeats the purpose.

    And how well would it work outside? Not well i would imagine.

  • I don't see how this can work at the speed they're claiming. 1+ Gbps means they're pulsing that light at sub-nanosecond intervals (or else doing something really amazing with frequency shifting, which I doubt). Since light travels less than a foot per nanosecond, if you're just bouncing it off the walls you're going to get echoes delayed by multiple pulse lengths and fractions of pulse lengths. Not a problem if the receiver is just seeing a single point, like in fiber, but how does that work in a room?

    • by jhfry ( 829244 )

      Hmm... you don't see how it can work, so it must not work.

      Perhaps they are using multiple light frequencies with multiple transmitters and receivers, each capable of only 100MB? Perhaps they simply know more than you do.

      I would wager that they are doing something relatively new, or the technology would have existed already... so it's not all that surprising that you don't understand it.

      • But where does the burden of proof lie?

      • by AJWM ( 19027 )

        Hmm... you don't see how it can work, so it must not work.

        Well, thank you for the implied compliment to my omniscience. Or perhaps that was just a massive fail of your reading comprehension ability. I never said that it didn't work.

        Perhaps they simply know more than you do.

        Gee, you think? If they actually got it to work, then in this one small area I'm sure that they do. Lots of people know more about certain specialized fields than I do -- your earlier comment above notwithstanding.

        they are doing somet

    • Yeah, we have no fucking idea how to deal with echoes. It's not like we have a cellular network that handles multi-path, selective fading, and moving transmitters... Light is a bit harder to modulate than radio frequency, but it's still just a wave, and we actually do have a few years (somewhere around 100) of experience with modulation schemes.

      The idea that you think they are pulsing a little light on and off at 1 GHz made me laugh out loud.

      • Light is a bit harder to modulate than radio frequency, but it's still just a wave,

        No, it's not a wave. There's this thing called a photon ... you might have heard of it.

        Just because light sometimes seems to act like a wave doesn't mean it is, any more than you liking to lick your nuts means you're a dog.


    • I don't see how this can work at the speed they're claiming. 1+ Gbps means they're pulsing that light at sub-nanosecond intervals

      What makes you think that? 1+ Gb/sec doesn't mean modulating at 1 billion times/second, it's a raw bit rate. Why couldn't they be using some encoding scheme that gets multiple bits/pulse?

      • by AJWM ( 19027 )

        Why couldn't they be using some encoding scheme that gets multiple bits/pulse?

        Amplitude modulation isn't going to work well in the described environment, and frequency-modulating a (single) laser diode is a good trick. It's an even better trick to FM demodulate that with a photodiode. Which leaves various pulse modulating techniques.

        There are a lot of things you can do with a radio signal that are a lot tougher to do with light.


        • There are a lot of things you can do with a radio signal that are a lot tougher to do with light.

          And there's a lot of things you can do in an unregulated spectrum that you can't do in a regulated one. One is simply the transmission power. I don't see why you can't do amplitude modulation with such a wide transmission range.

          and frequency-modulating a (single) laser diode is a good trick.

          So use multiple diodes at multiple frequencies.

  • by v1 ( 525388 ) on Saturday January 30, 2010 @03:02PM (#30964944) Homepage Journal

    users won't tolerate very intermittent connections, and won't tolerate having to aim their system at all. I remember using irda brirefly, and it was very touchy.

    Wifi is generally omnidirectional. light doesn't work that way - you can get a very strong signal 20 feet from it, or a nonexistent signal six inches away, if you're in a bad spot. And this effect occurs in both directions, and has different deadzones. So not only are you having a problem receiving, you're also having a differnt problem sending, requiring a great deal more adjustment to get communications going. Having to solve two positional problems simultaneously effectively quadruples the difficulty of the task.

    It's also going to be a great deal more environmentally sensitive. You can drop a bar or two if someone sets their laptop bag down beside your laptop and clouds direct line between you and the access point. Imagine how much worse that can get with light, and at a greater distance - you won't just lose a bar or two, you're almost certain to get completely disconnected. A couple chatting as they walk down the hall ten feet from you could ground you for several seconds, giving you absolutely no hint of what caused it.

    No, this technology's not going anywhere. Sure it works, but it's nowhere near as reliable as the public will demand. Look how badly people flip out now over an occasional dropped call.

    • I can see one use for it: ad-hoc networks. You wouldn't use it for a home network, but it would be nice for networking a few laptops together with no infrastructure, so people having a meeting can be on a network and exchange files easily.
      • by v1 ( 525388 )

        I can see one use for it: ad-hoc networks.

        I would agree with that. If I wanted to send something largeish to someone else where I was it would be useful to set our laptops back to back for example and basically irda a file over. Sort of like a fast bluetooth ad-hoc. In that scenario, physical arrangement etc is already expected to be optimized.

        I remember printing to an irda printer a long long time ago. (1999-2000 or so?) That was before 802.11 was around, and people were trying to figure out how I was

      • I can see one use for it: ad-hoc networks. You wouldn't use it for a home network, but it would be nice for networking a few laptops together with no infrastructure, so people having a meeting can be on a network and exchange files easily.

        Or they can use a $5 cable for transfers between two machines.

        Or they can just use a sub-$50 wireless router - the router doesn't have to be connected to any particular network to allow file transfers between participating computers.

  • by magsol ( 1406749 ) on Saturday January 30, 2010 @03:02PM (#30964950) Journal
    ...a friend of mine runs into the room in the middle of a download and starts playing with a flashlight?
    • by godrik ( 1287354 )

      he will receive a shoe in the head

    • Here's what happens when you read stuff and you're a bit drunk:

      What happens if... a friend of mine runs into the room in the middle of a download and starts playing with a fleshlight?

  • windowless rooms (Score:3, Insightful)

    by johnrpenner ( 40054 ) on Saturday January 30, 2010 @03:15PM (#30965054) Homepage

    great - so now millions of drones will have to sit in windowless rooms so the network wont leak out... and the air and the trees and the birds cant leak in... dismal existence... borg colony bleah! :-P

  • I'm wondering what frequency this will oscillate at and if this will potentially effect people proned to seizures ?

    • by phil reed ( 626 )

      To get up to a gigabit data rate, the pulses will be so fast you'd never see them. Even if it's multiplexed across many "frequencies" (colors), the pulsing will still be far faster than any eye could detect.

      Plus, you're assuming it would be visible. Infrared would be somewhat easier and cheaper to generate.

    • by Dunbal ( 464142 )

      I'm wondering what frequency this will oscillate at and if this will potentially effect people proned to seizures ?

      I don't think they would be so silly as to use a visible part of the spectrum. Rather I expect them to use the same frequencies used by say the remote control for your television. If it's invisible, it won't cause seizures because, well, it's invisible - the brain will not detect it. I have yet to read about television remote control induced seizures. Also if you're transm

      • They can't really use the IR frequencies that remotes use though, otherwise all of your A/V equipment will go nuts.

  • I know this is like super-secret insider knowledge in the IT consulting circles, but it's something that I just have to make public no matter what the consequences are.

    If you have computers in the same room that need to talk to each other, there's actually a really easy solution that is almost 100% reliable, doesn't require fiddling around with transmitters and sensors, and best of all only costs a cool $2 [google.com] for the whole solution.

    Just remember, you didn't hear this from me.

    • by cenc ( 1310167 )

      I was going to post a portable hard drive, but hey if people want to do it the hard way.

  • Light, in a room without windows, will not escape the room, improving security.

    That would be great, if that was what wifi was used for. But it is not. If the connection was limited to a single room, ethernet cables could be used, which would give even better security. Far more wifi systems are set up to get the network connection between rooms, even between floors of a house, than for networks in windowless rooms.

    Besides, everyone already knows that a computer room without Windows is more secure than

  • Another flashy headline. Who the fuck do they think they are, the sun?

  • by Angst Badger ( 8636 ) on Saturday January 30, 2010 @05:19PM (#30965986)

    Do not check network signal with remaining eye.

  • by CFD339 ( 795926 ) <andrewp AT thenorth DOT com> on Saturday January 30, 2010 @06:01PM (#30966280) Homepage Journal

          If I ignore the encoding issues and assume some mix of frequency and amplitude shifts or whatever to get that kind of bandwidth, I can go along with the idea that a well placed optical transmitter could bounce light around the room enough to do this -- but what about the return signal from the workstation or device? That would hardly be placed in an optimal location.

          Further, consider that wireless is most useful for mobile and transient devices -- laptops, sure; but what about cell phones, pda's, sensors, and all manner of other wireless things. These are frequently -- even usually -- not placed in direct visual sight.

          Frankly, I see this technology as potentially useful in long distance settings between stationary platforms (particularly in space) but not so much for day to day campus or home-office use.

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