Become a fan of Slashdot on Facebook

 


Forgot your password?
Close
typodupeerror
×
Communications Networking Wireless Networking Technology

Scientists Twist Radio Beams To Send Data At 32 Gigabits Per Second 122

Posted by samzenpus from the greased-lightning dept.
concertina226 writes Scientists from three international universities have succeeded in twisting radio beams in order to transfer data at the speed of 32 gigabits per second, which is 30 times faster than 4G LTE wireless technology in use today. The researchers, led by Alan Willner, an electrical engineering professor with the University of Southern California Viterbi School of Engineering, successfully demonstrated data transmission rates of 32 gigabits per second across 2.5m of free space in a basement laboratory.
This discussion has been archived. No new comments can be posted.

Scientists Twist Radio Beams To Send Data At 32 Gigabits Per Second More

Scientists Twist Radio Beams To Send Data At 32 Gigabits Per Second

Comments Filter:

  • At what signal to noise ratio? (Score:1)

    by Anonymous Coward

    Something tells me it's probably like +80dB, while real world conditions will expect -40dB. :-)

  • 2.5M? (Score:2, Funny)

    by dohzer ( 867770 )

    Should have used optical fibre.

  • Mom and Dad are pissed... (Score:5, Funny)

    by Anonymous Coward on Wednesday September 17, 2014 @11:56PM (#47934173)

    the University of Southern California Viterbi School of Engineering, successfully demonstrated data transmission rates of 32 gigabits per second across 2.5m of free space in a basement laboratory.

    They would have tried for 10m, but Mom and Dad told them that the street lights were on, and their little friends would have come up from the basement and go home.

  • Crawl, *then* walk (Score:5, Insightful)

    by Space cowboy ( 13680 ) on Thursday September 18, 2014 @12:03AM (#47934209) Journal

    Yeah, I could do with one of those office-space meme's right now.

    If all the nay-sayers faux-gasping at the extreme length of 2.5m could shut up, that'd be great.

    I'm not sure what people expect these days - this is a major achievement - whether it *can* be extended, or whether it *will* be extended would be different achievements. You could almost apply Jackson's rules of optimisation to this (refresher below) - in that first you *do* it, and only then (if you're an expert) do you try to do it *well*.

    Simon

    Jackson's rules of optimisation: "The First Rule of Program Optimization: Don't do it. The Second Rule of Program Optimization (for experts only!): Don't do it yet."

    • One would assume at least some of the Slashdot crowd has been to college and knows what a scientific paper is and how research and experiments are conducted, but clearly a college education isn't enough these days.

    • A lot seem to be concerned about usefulness for broad use, as in how will it fare for end points like mobile phones or wifi access. However even if it never becomes useful in that arena what I want to know is how it will fair for longer distance communications, for specific uses rather than mass market consumers. Places where point to point radio is currently being used, or possibly where wired connections at a lower speed are in use. 2.5m is not much but it's just early work, so if it can be extended th

  • I notice from the diagram (per the linked story [ibtimes.co.uk]) that I only need to fit a spiral phase plate (no, not a flux capacitor [wikipedia.org]) to my Tardis [wikipedia.org] and it all works automagically...

    ... via "orbital angular momentum [wikipedia.org]" and "OAM multiplexing [wikipedia.org]".

    Frankly, I am still confused as to why it's not (more simply) "circular polarisation [wikipedia.org]" that has been known about since the early days of radio.

    • dynamic twisting (Score:2, Interesting)

      by frovingslosh ( 582462 )
      Well, there seems to be a lot of information missing, but I'm suspecting that when they talk about twisting the radio signal they don't just mean static circular polarization, they mean that they are dynamically twisting it variable amounts as a way to modulate the data signal onto it. This would be similar to the modulation techniques used back in the last millennium to squeeze far more data down an audio like than the audio bandwidth would imply could be transmitted.

    • Re:Spiral filter, and a Tardis (Score:5, Informative)

      by zalas ( 682627 ) on Thursday September 18, 2014 @01:36AM (#47934457) Homepage

      Frankly, I am still confused as to why it's not (more simply) "circular polarisation [wikipedia.org]" that has been known about since the early days of radio.

      Since you linked to Wikipedia, I'm going to assume that Wikipedia didn't do a very good job at explaining the difference. While OAM and circular polarisation both describe some sort of spinning, they correspond to different phenomena. As you may know, electromagnetic waves are oscillations of the electric (and magnetic) field, with the field at each spatial position varying over time. You may also recall from your high school physics class that the electric field at any position is a vector quantity --- it has both a strength and a direction. The polarisation of a electromagnetic field is a description of the direction that the electric field points, and circular polarisation can be roughly seen as the electric field direction rotating as you travel in the direction of propagation. What OAM is describing is the phase relationship between the oscillations of the field at different positions (whether the oscillation at one point is lagged or ahead compared to a different point); it can be roughly thought of as a spinning motion in the transfer of energy inside an electromagnetic field.

      For a rather inaccurate, but perhaps intuitive, analogy, try imagining a giant stream of asteroids coming your way in outer space. If the rocks are following a spiral trajectory as they come at you, then this corresponds to the rocks having "orbital angular momentum". If the rocks are themselves spinning, then this corresponds the rocks being "circularly polarised".

      • Re: (Score:2)

        by dtmos ( 447842 ) *

        So let me ask: If the multiplexing is due to "the phase relationship between the oscillations of the field at different positions", may I assume that these systems would be very sensitive to multipath interference -- especially varying multipath interference, as in mobile devices? Is that why the only demonstrations I have seen involve point-to-point links in free space (where multipath would be minimized)?

        • I feel like I'm in an episode of The-Big-Bang-Theory....

        • Re: (Score:2)

          by Bengie ( 1121981 )
          As for free space twisted light, 32gb is slow: http://spectrum.ieee.org/tech-... [ieee.org] Jun 2012 "Scientist in California and Israel say they've transmitted data through the air at a rate of 2.56 terabits per second using beams of "twisted light.""

          • This earlier work you're referring to was led by the same person, Alan Willner of USC. Here he's essentially taken the techniques he used at optical frequencies and applied them to millimeter waves.

      • Re:Spiral filter, and a Tardis (Score:4, Informative)

        by Anonymous Coward on Thursday September 18, 2014 @06:54AM (#47935207)

        As a microwave engineer, I find it unfortunate that it is called "orbital angular momentum" or "twisted beams". It causes confusion for many in the antenna engineering community. It is _not_ circular polarisation, but a form of spatial diversity non unlike MIMO systems. Where it differs from MIMO is, instead of translational spatial diversity, we have angular spatial diversity. The "beams'" phase fronts "twist" at different rates (there is no "twisting" of the direction of the E-field vector, as is the case with circular polarisation). This provides a means to multiplex many signals on the same "beam". Incidentally, you can also exploit polarization on top of the angular spatial diversity to (nearly) double the transmission capacity.

        • Thanks. This is a little more understandable, once I read the wikipedia entry and saw the phase diagram.

        • Thanks for the explanation. So would it be correct to say that these guys have come up with a new type of waveguide then?

  • This won't amount to anything... (Score:4, Interesting)

    by Electricity Likes Me ( 1098643 ) on Thursday September 18, 2014 @01:15AM (#47934413)

    It's been shown that all these "helical" polarization schemes are degenerate forms of MIMO essentially, and can't achieve speeds better then what MIMO antenna configurations can.

    At short distances in quiet environments, you can do a heck of a lot which will never, ever work anywhere but in that experiment.

    • I was going to say the same thing. It's total rubbish in it's claims. Being just yet-another-linear combination of MiMo modes it provides no additional channel capacity. But there is the possibility that the demodulation/modulation methodology is easier to implement than other fast modulation schemes.

      • But there is the possibility that the demodulation/modulation methodology is easier to implement than other fast modulation schemes.

        This is the key point. MIMO schemes require a lot of complexity in the receiver, which is workable at Wifi/LTE frequencies of a few GHz where you can get electronics to reliably function. Here he's working at millimeter wave frequencies (30GHz to 300GHz) were electronics either doesn't function, or is extremely expensive. You could think of this work as a MIMO-like spatial multiplexing scheme that doesn't require complex processing in the receiver, and is therefore implementable at very high frequencies.

        As

    • I would think that MIMO can do quite a lot in a stationary environment, though it is useless if the environment changes significantly, especially if sender or receiver is moving. A polarization scheme may be imune to that. What do you think?

    • It's been shown that all these "helical" polarization schemes are degenerate forms of MIMO essentially, and can't achieve speeds better then what MIMO antenna configurations can.

      While it may be argued that circular polarization is another MIMO scheme, it CAN achieve better speeds, because it DOESN'T REQUIRE EXTRA CHANNELS. MIMO, generally, does. There's nothing 'degenerate' about the relationship of the two schemes.

      The real limitation here, is that this is a beam technology, it isn't for broadcast (i.e.

  • from the diagram, it looks to be a directional antennae.
    if you are doing that with radio waves... why not a laser?

    • If you are doing that with radio waves... why not a laser?

      Have you seen the prices for sharks lately?

    • Re: (Score:2)

      by sconeu ( 64226 )

      Because sharks are too unreliable, and you always need a bigger boat than you think you will.

  • It's still modulation, modulation creates sidebands, and sidebands require bandwidth.

    Nothing has changed, the Shannon–Hartley theorem still rules.

    • Re: (Score:1)

      by labnet ( 457441 )

      It's still modulation, modulation creates sidebands, and sidebands require bandwidth.

      Nothing has changed, the Shannon–Hartley theorem still rules.

      It's not modulation, it's multiplexing using a constant angular momentum. Modulation requires a change in something. With this case the they are sending seperate radio streams using different but constant rotated angluar momentums.
      Think of it like 3D glasses in movie cinema that use right and left hand polarised light.

      • Re: (Score:2)

        by Ozoner ( 1406169 )

        Any kind of Multiplexing requires additional bandwidth.
        TANSTAAFL.

        If there's no change, there's no data encoded.

        • Re: (Score:1)

          by Anonymous Coward
          This uses less bandwidth in frequency space than a more traditional scheme with the same amount of data capability (unless implemented badly). It uses spatial structure to separate several channels operating on the same set of frequencies. That is the same as how you can double your data rate without using any extra frequencies if you use two fibers (or two wave guides) to keep two channels separate. The difference here, is that it craps out with distance really fast as at some point the spatial structure

  • Nice diagram of a left-facing swastika in the article - or is that a southern-hemisphere hurricane?

  • Dr. Egon Spengler: There's something very important I forgot to tell you.
    Dr. Peter Venkman: What?
    Dr. Egon Spengler: Don't cross the streams.
    Dr. Peter Venkman: Why?
    Dr. Egon Spengler: It would be bad.
    Dr. Peter Venkman: I'm fuzzy on the whole good/bad thing. What do you mean, "bad"?
    Dr. Egon Spengler: Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.
    Dr Ray Stantz: Total protonic reversal.
    Dr. Peter Venkman: Right. That's bad. Okay. Al

  • Same old (Score:2, Interesting)

    by Ol Olsoc ( 1175323 )
    Seems like once or twice a year, People discover phase encoding. Promises of narrow bandwidth and high transmission rate are so tempting.

    And just to really get people excited, you can give the signal another "twist", and another, and another - "HEY! It looks like we can achieve infinite bandwidth!!"

    Along with using infinite spectrum and requiring infinite power

    This really isn't anything all that new. Hams have been using phase change modes for around 15 years now. Some of these modes, like PSK-31, all

    • Re: (Score:1)

      by tlhIngan ( 30335 )

      Seems like once or twice a year, People discover phase encoding. Promises of narrow bandwidth and high transmission rate are so tempting.
      And just to really get people excited, you can give the signal another "twist", and another, and another - "HEY! It looks like we can achieve infinite bandwidth!!"

      Or... how people keep trying to outwit Shannon [wikipedia.org].

      And they fail (after all, that theorem states the maximum achievable data rate using any kind of whimsical encoding you can dream up including ideal given a bandwidt

  • This is like QAM? I recall back in the late 1980's some AM broadcasters had played around with Quadrature Amplitude Modulation. In essence twisting the phase of the carrier around to get channeling, etc.
  • Interesting and a good start but . . .

    (Hard to tell clearly from the two articles but) these seem to use feed horns of a specific design and configuration (microwave transmissions usually do), that must be POINTED AT the receiver feed horn, so . . . if anyone is planning on "just plopping down the laptop" in any old orientation . . . it won't line up the transmission signals. Sure, for a trunk line between sites (buildings/planets) where critical alignment can be achieved . . . it'll work fine.

    And some

  • Ahhh...the goal of continuous, direct-to-brain, high quality porn streams continue to be driven apace.

    Excellent.

Slashdot Top Deals

Beware of all enterprises that require new clothes, and not rather a new wearer of clothes. -- Henry David Thoreau

Close