Slashdot is powered by your submissions, so send in your scoop


Forgot your password?
Networking Wireless Networking Communications IT

German Scientists Achieve Record 100Gbps Via Wireless Data Link 67

Mark.JUK writes "A joint team of German scientists working at the Karlsruhe Institute of Technology (KIT) have successfully achieved a new world record for wireless data transfers. The team were able to transmit information at speeds of 100 Gigabits per second by using a radio network operating at the frequency of 237.5GHz and over a distance of 20 metres (note: a prior experiment hit 40Gbps over 1km between two skyscrapers). The radio signals were generated by a photon mixer device that uses two optical laser signals of different frequencies, which were then superimposed on a photodiode to create an electrical signal (237.5 GHz) that could be radiated via an antenna. But the team aren't happy with breaking one record and their future attempts will seek to break the 1 Terabit per second (Tbps) barrier."
This discussion has been archived. No new comments can be posted.

German Scientists Achieve Record 100Gbps Via Wireless Data Link

Comments Filter:
  • by Arker ( 91948 ) on Tuesday October 15, 2013 @08:33AM (#45131407) Homepage

    So sick and tired of people equating bandwidth with speed. Is a tractor trailer faster than a Ferrari?

    So what kind of ping do they get on this link?

    • by Trepidity ( 597 )

      Eh, it's a pretty colloquialism even in other parts of science to use "speed" to refer to a rate rather than only a velocity.

      • Look at the speed of that cargo ship!
      • Expressing proper units and dimensions seem to be difficult for the layman, the press and even for the /. audience. mWh, MW or kW/h, it's all the same. And every time a car is moving at a high rate of speed, Newton rolls a few radians in his grave.

    • Well, the latency is ultimately going to be limited to the speed at which electromagnetic waves propagate through air, which at the refraction index of 1.0003 hardly differs from the 3x10^8 in a vacuum. Most of the latency will be introduced through the processing, although if there is much that would be trivial to address. I doubt processing power will be a difficult problem.
    • Re:Speed? (Score:5, Informative)

      by Arancaytar ( 966377 ) <> on Tuesday October 15, 2013 @08:54AM (#45131601) Homepage

      Electromagnetic waves through air propagate at approximately .9997c.

      • by Arker ( 91948 )

        Do you work for microsoft?

        Because that fit the classic microsoft pattern - technically correct, but unresponsive/not relevant.

        The time spent in the transmission of the signal is only one (probably the smallest one) of many factors that add up to produce the latency of the link.

    • On a semi-related note, why is the latency of WiFi so sucky? I recently tried to mount an NFS home partition on a WiFi with 50 Mb tested throughput, and it was noticeably bad, to the point I broke down and ran a cable. Granted, it's a pretty sad network filesystem that performs so badly with 1-4 ms of latency. But even that is much more than wired... why? It's obviously not the flight time of radio waves over 30 feet. There shouldn't be too much re-transmission at the wireless protocol layers, for su
      • Full disclosure, I just remembered that it was a USB WiFi adapter on the client, which doesn't help latency any. Still, I have yet to use WiFi on any other computer that had near-wired ping times either...
        • IIRC, USB will add up to 10ms of latency to whatever youre using USB for.

        • On a wire (or fiber), there is less contention for the available bandwidth. One device on each end of the string.

          On WiFi, with everyone on channel 6, there can be interference and multiple devices having to wait their turn to talk.

      • by Arker ( 91948 )

        It's a very good question. Often it has to do with obviously inferior/shoddy consumer electronics design, but even the better wireless hardware does still seem to impose significantly greater latency than an ethernet cable for the same distance, and even on the best of days.

        On the worst of days, there is significant interference and that can cause a lot of retries and massive performance degradation, but that's a pile of different issues, whether sunspots or faulty wiring or the weather or whatever.

      • by ziggit ( 811520 )

        If I'm not mistaken, WiFi has also traditionally been half duplex. This may have changed with some of the newer N stuff tho, I haven't really kept up. So that would definitely cause problems. That being said, if a half duplex link can kill NFS performance, I can only imagine what that would have been like in the days of thinnet.

    • by fatphil ( 181876 )
      Are you trying to say that other RF comms technology is slower, but can carry more at the same time? Which wouldn't really stand up to much scrutiny at all.

      A far better stupid analogy is to say that this is basically just the same as frisbeeing a dual layer DVD across a tennis court every 4 seconds.
    • is that an African or European ....
      Unladen or laden ...

    • by prefec2 ( 875483 )

      The correct terms are throughput vs. response time. Throughput matters for many applications including video streaming. Only interactive applications, such as tele- or videophone require low ping rates, meaning low response time.

      • by Arker ( 91948 )

        "The correct terms are throughput vs. response time"

        Thank you. I actually misused 'bandwidth' egregiously in my initial post and I am shocked no one has flamed me for it yet, but at least you pointed it out, if indirectly.

        Throughput just doesnt equate to 'speed' even approximately though. Response time (latency) does so it's hardly unreasonable of me to point out that marketing has no idea what they are talking about. Preserving the language of Shakespeare from these cretins is in everyones interest.


      • Low latency matters considerably depending on the type of protocol you're using. If you have any kind of congestion control, which you should always have unless you're using a fixed bandwidth dedicated link from end to end, high latency will cause some serious problems as soon as you start dropping data.
  • Damn it. (Score:5, Funny)

    by fuzzyfuzzyfungus ( 1223518 ) on Tuesday October 15, 2013 @08:37AM (#45131427) Journal
    Oh for the days when our German scientists where better than their German scientists. Truly a golden age for American Innovation.
    • Even our movie stars were inventing the beginnings of wireless networks.
      • by weav ( 158099 )

        You talking about Hedy Lamarr here?

        • by Anonymous Coward

          Who was, of course, one of our German actresses (actually, Austrian, but the countries are very closely associated...)

          The Americans owe a lot to the Europeans. I seem to recall that the Brits gave us the Jet engine, Radar, Sonar and the start of the Atomic Bomb project (Tube Alloys, which changed into the Manhattan Project) during the war.

          They tried to give us the Convoy System as well, but our admiral hated the Brits so much he preferred to have American ships sunk by U-Boats rather than take British advic

          • That was the great thing about 20th century Europe: brilliant enough to invent all kinds of neat stuff, theoretical and applied; but dumb enough to fight two nigh-apocalyptic meatgrinder wars of unprecedented brutality for reasons somewhere between 'kind of silly' and 'so baffling that historians have made entire careers out of them', thus driving much of said brilliance to the US! It'd be pretty sociopathic to suggest as a deliberate talent-recruitment strategy; but as an accidental side effect it served
        • Of course I am. Hedy Lamarr was pretty cool! :D
    • Oh for the days when our German scientists where better than their German scientists. Truly a golden age for American Innovation.

      Don't feel bad. They have had hundreds of years of experience with German scientists, whereas the Americans with mere decades are relative newcomers in this field.

  • At least SOMEBODY in the West remembers how to make things and innovate (and I don't mean 'innovate' in the sense of wizarding up even more financial and managerial bullshit).

    Management and finance don't create value, techies and innovators do. Unfortunately, stupid, spoilt rich kids head into law and finance, so our clueless overlords prioritize that.

    • Management and finance obtain the funding and drive the demand for the technology. This is what you call a "necessary evil".
    • by prefec2 ( 875483 )

      Tools are made by engineers. They shape the options to manipulate our environment. Our elite overlords determine how they are used. Sometimes they miss something and we get printing or the Internet out in the public ;-)

  • by P-niiice ( 1703362 ) on Tuesday October 15, 2013 @08:52AM (#45131587)
    I'd hit my cap in 20 seconds
  • by P-niiice ( 1703362 ) on Tuesday October 15, 2013 @09:11AM (#45131771)
    Now if only we could innovate in the usage cap area.
  • Slighly tangential line of thought here:

    Let us imagine a cylinder of empty space with radius r = 5mm and length l = 10 meters. Allowing for any kind of medium in this space (fiber, copper, neutron-star matter, etc...), what is the maximum throughput in principle of this communication channel?

    In other words, I've been wondering lately if there is an upper-bound (in principle) on bandwidth. Like how there is a speed limit for light, is there something similar for information transmission?

    • You've got the Shannon limit, describing the ultimate channel capacity in terms of bandwidth and signal-to-noise ratio. You can increase your bandwidth, but your transmission medium will eventually impose attenuation limits. You can increase your power output, and thus your SNR, but you eventually reach a saturation limit from blooming, ionization, or melting of your medium. There is no theoretical limit on channel capacity, unless you want to go into information theory and figure out the maximum amount

Our OS who art in CPU, UNIX be thy name. Thy programs run, thy syscalls done, In kernel as it is in user!