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Japan Communications Networking

Scientists In Japan Build 100Gbps Wireless Network Using Terahertz Transmitter 49

Mark.JUK writes: A group of Japanese scientists working on a project managed by Hiroshima University claim to have successfully built a Terahertz (THz) transmitter, which is implemented as a silicon CMOS integrated circuit and can transmit a signal running at 10Gbps per data channel over multiple channels in the 275-305GHz band for a top speed of 100Gbps (Gigabits per second). But crucially nobody has mentioned the distance at which this speed could be achieved, particularly since the THz band isn't likely to have much of a reach. It also sits very close to the region used by lasers.
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Scientists In Japan Build 100Gbps Wireless Network Using Terahertz Transmitter

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  • Huh. (Score:2, Insightful)

    TIL lasers have their own band in the EM spectrum.

    • That band is called "light", hence the 'l' in laser.

  • It also sits very close to the region used by lasers.

    Within firing range?

  • TFA says "and now another team claims it can hit 100Gbps by pushing into the TeraHertz (300GHz+).". Nyquist can stop spinning.

    • by Plammox ( 717738 )
      Did you ever hear about quadrature modulation?
    • by Khyber ( 864651 )

      That doesn't actually preclude physics. We can get multiple bits of information from a single photon. QAM, frequency, phase-shift, etc. The theorem still holds across almost every perceivable 'sound effect' until you get to the matter of pitch shifting, in which case, even with the minimum 2x sampling rate, the reality is that you need about 32x that amount to get an accurate signal representation that won't distort across a wide range of frequency shifts.

      There's a reason Nyquist-Shannon has a "THEOREM" ins

  • throw in a running microwave oven and at a distance of 1/2 mile.
  • It sounds wonderful but will it cook my turkey if I leave it on the window sill?
  • Maybe this is more useful for direct data links? Might be a good way to send data across the ocean.
  • I seem to remember a publication in Nature [nature.com] from 2013. Seems the Germans already did something comparable a few years ago. Over 20m distance that is.
  • 4G has offered these speeds for years between cell towers. For individual towers, it gets split among all users and phones, which also don't use enough power to upload at the same speed and range as the tower. But a THz transmitter sounds interesting. Anyone know if the propagation would be better/worse? I would imagine worse?
    • Terahertz signals would only reach 10's to maybe 100 meters, AND they're blocked by metal or water.
      (i.e. a human standing next to the router might cause significant signal loss). Probably good enough
      for indoor use, though --- at 100 gbps you could afford to retransmit lost packets.

    • Who's using 100Gbps wireless links for cellular backhaul?

  • 100 Gbps is roughly 14 gigabytes per second. So I would use up my 5GB monthly Verizon cap in about 1/3 a second, then begin racking up $10 /gig overages at $140/s.

    • How do you come up with those figures?
      I get a theoretical maximum of 12.5GB/sec and I've _NEVER EVER_ encountered a wireless data transmission system that comes anywhere close to it's apparent maximum. Ever.

      Wireless A,C,N,G etc - all of them, you should basically divide by 8, as standard and then halve it again. If you're lucky, maybe you'll get 60% of the claimed maximum, maybe.

      I would imagine a 100Gbps system to give a real world figure (pulling this directly from my ass as I type this,.. based on experi

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