back to article Japanese team unveils terahertz band 100 Gbps wireless tech

Terahertz transmissions, literally the last frontier of radio communications, come a step closer this week with a group of Japanese researchers demonstrating a 100 Gbps system at an IEEE conference. The researchers, from Hiroshima University, Japan's National Institute for Information and Communications Technology, and …

  1. David Roberts
    Paris Hilton

    Naive question

    If this is designed for extremely high bandwidth over kilometres between cell towers, is there enough power to cook sausages or the occasional pasding bird?

    Or does "not absorbed by water" come into it?

    1. tony2heads
      Boffin

      Re: Naive question

      There is a very strong water absorption line just above 300GHz, so I a sceptical about its use anywhere foggy.

      1. Paul Crawford Silver badge

        Re: Naive question

        Rain attenuation is very high at those frequencies, but also it is not something that is well characterised (yet) as no one really has measured it for long enough to validate the model's upper range.

        http://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.838-3-200503-I!!PDF-E.pdf

        You will notice the ITU-R models have no accuracy/error bounds on them...

    2. Hans 1
      Paris Hilton

      Re: Naive question

      High frequency means the reception area is small, the higher you go, the smaller the reception area, at any given intensity. To get Ghz over a km needs quite some energy, then, consider the effects water in the air has ... this is just .... silly!

      There must be something I don't know that these guyz know, 'coz, well, I know close to close to nuthing about radio signals, except ... the shorter the wavelength, the more energy you need to reach a given reception area.

      1. Paul Crawford Silver badge

        Re: Naive question

        It is not naive, in fact it is a very fundamental aspect the most radio courses gloss over!

        Basically you have two antenna aspects: (1) "directivity gain" which is a measure of how much a beam is focused (there is no amplification), and (2) "effective aperture" which is a measure of the antenna's ability to intercept the EM flux.

        As frequencies go up (generally speaking here, YMMV, etc) you get more easy focusing from a given reflector, etc, so directivity gain increases, but your effective aperture remains the same. To make calculations easier a radio link's "path loss" has a wavelength term, it is more than just inverse-square law spreading with distance, so that at constant flux and constant aperture you get the same signal even though the directivity gain increases with frequency.

        So for two antenna pointing at each other, increasing the frequency would lead to a stronger signal due to the higher directivity gain, but at the expense of needing more accurate pointing. Conversely, if you keep the RF flux constant (so you get the same coverage area, same pointing error accuracy demands, etc) then increasing frequency has the opposite effect in that smaller reflectors, etc, are used to keep the directivity down, and so less aperture able to intercept the flux.

    3. Anonymous Coward
      Anonymous Coward

      Re: Naive question

      Fwiw, the EMR band from 300GHz-430THz is classed as Infra Red.

  2. Mage Silver badge

    It's very niche

    High Altitude platforms (which as yet are not viable). Satellite mesh networking among satellites.

    Actual terrestrial range is pure line of sight and very limited by weather.

    Infra red laser is nearly more useful. It's a lab party trick, because they can.

    The "spectrum" shortage is a myth. The whole point of Cellular is to re-use the same nine channels (minimum is three, but nine is better if a mast only uses 3, one each per 120 degrees). The problem is two fold:

    1) Stupidly having more than one wholesale operator. If you have four, then you need x4 spectrum.

    2) Not enough basestations. Because of ROI, it's not economic to have smaller cells and give people x10 speed as they won't pay much more.

    The real impetus of selling off TV spectrum, Army & satellite spectrum to mobile is:

    1) Extra licence revenue to Regulators and thus Government.

    2) Cheap low capacity for rural without building new masts, use the GSM ones,

    3) Cheap extra capacity in cities, to compete with WiFi points, without extra masts. This is why they want LTE on WiFi, use existing band, tech and charge you more.

    1. Anonymous Coward
      Anonymous Coward

      Re: It's very niche

      And at times, 4x underused spectrum, that can't be used due to the equivalent of Supermarket landbanking. Virtualised base stations, with offsite centralised RF processing in the cloud (which is one of the design goals of 5G, to lower ROI in maintaining multiple smaller cell sizes), has to be the way forward. i.e. no one can "Landbank".

      "This is why they want LTE on Wifi"

      Do you mean the frequency spectrum here? i.e. Microware frequencies or did you mean use of femtocells / nanocells / BT Home Hub 7 , Vodafone Sure Signal type devices that relay the mobile LTE signal via a femtocell connected to a consumer grade backhaul FTTC/Virgin Media Broadband, or where you use your own home router to route a call over your own Wifi signal. It's all of the above.

  3. Anonymous Coward
    Anonymous Coward

    I can imagine the ads now

    Up to 3THz!

    Actual frequencies may vary, 3THZ based on top 10% of users. 80% can expect 300 -300.000001 MHz.

  4. Anonymous Coward
    Anonymous Coward

    > showing off kit that delivers a baseband frequency of 300 MHz.

    > "But that's less than a third of a Terahertz!”, we hear you cry

    Hmm, my cry was "But that's less than a third of a Gigahertz!"

    1. DavidRa

      Technically they're still not wrong...

  5. Anonymous Coward
    Anonymous Coward

    Rural Folk aren't this fcuking stupid.

    To use rural folk here, as though it gives them some sort of extra hope, is just plain annoying, even when it's tongue-in-cheek, El Reg.

    This isn't a practical solution either in cost terms, delivery, or robustness in any realistic timeframe - Period. Given the crumpled up carpet topology/landscape of most of rural Britain, it's a non starter. This is blocked by any object in line of sight, i.e trees.

    No doubt, BT folk will use headlines like this to generate even more 'hope' and 'upto' obfuscation to the clueless, that 'new Tetrahertz Wireless technologies and Pointless G.fast 'can meet the UK's needs (they can't) to avoid separation, investment in fibre optic / more real fibre cables in the ground.

    We have practical headline-free 'boring' FTTP technology to do this already, it's just we have a incumbent that is doing everything in its powers to remain with it's legacy copper carcass tech.

    We don't need to revent the wheel, but we do need to stop talking and put more fibre in the ground as cheaply as possible, to the door, get rid of legacy copper over time, but starting now. We need to say as a nation, no more copper technology, it's reached practical usefulness, we can see the end of this copper tunnel now and the exit is blocked, a new direction is needed.

    We really should have a minimum litmus for headlines like this. Could this technology deliver 4K streaming to the whole of the UK, IRRESPECTIVE OF LOCATION - to multiple devices per home, using iPlayer technologies to say, stream the 2018 World Cup Final?

    For Rural folk, let's be realistic, we're mostly stuck BT. It's best to use 2030 World Cup Final analogy here. In terms of BTSport/the World Cup it's not just Football 'players in this game' that drag their feet and look for 'sponsorship' (aka. handouts) at every opportunity.

    1. Anonymous Coward
      Anonymous Coward

      Re: Rural Folk aren't this fcuking stupid.

      Is there any topic you don't turn into a rant about G.Fast?

      How does Japanese radio research have any bearing on UK broadband?

      1. Anonymous Coward
        Anonymous Coward

        Re: Rural Folk aren't this fcuking stupid.

        Is there any G.fast 'rant' you don't pointlessly reply to say shut the fcuk up? Nothing worse than telling people in a roundabout way to shut up, about things they don't want discussed, for incumbent commercial/Pension/BT shareholder reasons.

        Pointless G.fast is dead in the water anyhow, it won't get another penny from the UK taxpayer, is how its looking at the moment and it really shouldn't.

        1. druck Silver badge

          Re: Rural Folk aren't this fcuking stupid.

          To prevent you bickering bunch of ACs call each other shills, either post in your own names, or take each others advice and shut up.

      2. SImon Hobson Bronze badge

        Re: Rural Folk aren't this fcuking stupid.

        Is there any topic you don't turn into a rant about G.Fast?

        Did you actually read his comment ? Like starting from the first line about giving rural dwellers false hope, and then going on to speculate about how BT is likely to use any excuse to avoid what needs to happen. Yes it's a bit of a rant, but to be blunt - it's mostly right on target.

    2. phuzz Silver badge
      IT Angle

      Re: Rural Folk aren't this fcuking stupid.

      Normally I'd be right in on a "rural folks can't get no bandwidth" rant. However, BT have finally decided to drag a fibre all the way to the village I grew up in, so some time in the next few months my folks should be getting an upgrade from their >1MB ADSL connection.

      So just be patient AC, sooner or later that bendy glass will reach you.

  6. comtechnet

    You said ...

    If you're looking at a 300 GHz bearer, every 1 GHz (say, from 300 GHz to 301 GHz) accommodates 20 of those channels. It's an awfully big resource ...

    Isn't this WRONG - shouldn't it be 50 channels that it can accommodate?

  7. Fred Goldstein

    Rain fade is severe up there

    These frequencies have very short range. And I don't know why the reporter thinks that rain fade ends at 55 GHz! We manage a bunch of 80 GHz links and I can tell you how hard it rained at a given time by the amount of rain fade. Fun detail: It snowed in most of the Boston area this morning. Snow doesn't cause rain fade. So most of the 80 GHz links stayed pretty steady. But two of them faded a lot, about 25 dB. Those were right near the seacoast, where it was just a tad warmer and the precipitation fell as rain. The rain fade chart tells me. In fact from one building, an eastbound link faded while a westbound link didn't. Yep, very sensitive to rain.

    While (as someone else noted) it may not be precisely characterized, rain fade still rises with frequency. At 300 GHz expect very short range or depend on very sunny weather.

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