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London UK Team Achieves Record 178Tbps Single Fibre Speed

Saturday, August 15th, 2020 (8:02 am) - Score 2,745

Scientists at the Optical Networks division of University College London (UCL) have successfully used experimental “hybrid discrete Raman and rare-earth doped fibre amplifiers” to achieve a record single core, single mode fibre throughput (net) speed of 178.08 Terabits per second over a distance of 40km.

As the research paper explains, the maximum data throughput in a single mode optical fibre is a function of both the signal bandwidth and the wavelength-dependent signal-to-noise ratio (SNR). Scientists are forever pushing the boundaries of performance on optical fibre cables forward and the latest one from UCL involves highly efficient amplifiers to “enable wide-band signal gain, without spectral gaps between amplification bands.”

The work ultimately resulted in a record transmission throughput for a single core, single mode optical fibre, using a continuous, ultra-wideband (16.83THz) transmission window. The previous record for such a cable at a distance of 40km and using the S,C and L bands was set at an already highly impressive 150.3Tbps, while the new setup hit a net throughput of 178.08Tbps.

A fairly new method of Pilot-based Digital Signal Processing (DSP) was also used in the setup, which was created last year by a different team of researchers.

Short Technical Summary

We describe the widest continuous coherent transmission bandwidth experimentally demonstrated to date of 16.83 THz, achieved by simultaneously using the S-, C- and L-bands. The variation of fibre parameters over this bandwidth, together with the hybrid amplification method result in a significant SNR wavelength-dependence. To cope with this, the signal was optimised for each SNR, wavelength and transmission band.

By using a system-tailored set of geometrically shaped constellations, we demonstrate the transmission of 660 ×25 GBd channels over 40 km, resulting in a record single mode fibre net throughput of 178.08 Tbit/s.

The research team, based out of a lab in Bloomsbury, was led by Dr Lidia Galdino who said (Standard) they “managed to achieve the highest bandwidth that has ever transmitted through the internet. I think the societal benefit is clear – fast internet for all and a more productive economy. It’s important because internet traffic and data has been increasing exponentially over the last 10 years but we have reached the theoretical limit.

Obviously, you’re unlikely to see this sort of speed being delivered to homes anytime soon, but it is the sort of development that’s likely to be harnessed in the future for boosting the performance of longer international and national fibre routes. The ability to carry more data down existing cables also tends to result in cheaper capacity from suppliers, which ultimately benefits everybody. Well done.

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14 Responses
  1. Avatar Jack Court says:

    Typical…the big cities leading the way with faster speeds again. I’ve heard there’s also another university in London conducting similar research which just seems completely unfair when there are no universities in the Cotswolds looking into this.

    1. Mark Jackson Mark Jackson says:

      ^ I assume that’s meant to be a joke and not a serious comment 🙂 ?

    2. Avatar Polina Bayvel says:

      UCL is the only team in thd UK capable of these speeds and ond of only z handful in the world…workinv out of a lab the size of a sitting room, 5 mins walk from the British Museum!

  2. Avatar Chris Sayers says:

    I wonder when the conspiracy theorists will start to complain that the electromagnetic transmission from FTTP connections are impacting their mental health.

    1. Avatar Simi says:

      Yes they need to upgrade their tin hats.

  3. Avatar Buggerlugz says:

    Chris, you’re not allowed to speak of EM interference causing ill effects to peoples health on here! (Mark has a tendency to disable comments when posting about 5g conspiracy idiots, see post above.)

    1. Avatar CarlT says:

      Presumably he has better things to do on a Saturday, or any other day, than moderate dangerous disinformation that has already led to several crimes and other risky behaviour?

    2. Mark Jackson Mark Jackson says:

      Ofcom has warned media publications that they could face sanctions if found to be spreading conspiracy claims. Since some people were using news comments to spread such vile conspiracy theories then we chose to impose that restriction to limit our liability. But let’s keep this on-topic shall we.

    3. Avatar Chris Sayers says:


  4. Avatar CarlT says:

    Those numbers are insane.

    16.83 THz of bandwidth, 178.08 Tbit/s of throughput.

    I fully imagine that if other overheads are taken into account they’re getting on average 2048-QAM out of the channels.

    That is insane. I can believe that, with the understanding we have now, that’s the Shannon limit for that bandwidth.

    Not going to see close to that in production networks, that link was manually groomed and tuned like crazy, but it bodes well. Given production networks are sitting at 64-QAM, the potential for good channels to deliver 2048-QAM is fantastic.

    1. Avatar Simi says:

      Max will still slate G.fast and this for not being £1 a month.. wait and see

    2. Avatar Polina Bayvel says:

      Very true re future potential!! Not tuned wildly and more room to improve but as you say – it bodes well for tge future!

    3. Avatar CarlT says:

      My apologies, Dr, for misunderstanding you. I thought the QAM constellations had been built around the signal characteristics and that a quote in the article indicated Shannon limit had been about reached.

      I have seen the constellations used. Somewhat different from the standard square constellations.

      I suspect this is way beyond me but, when I have the time, I’ll re-read the article and citations and try and understand why the constellations are shaped that way.

      The SNRs you have managed to get those modulation orders out of are remarkable. Not that long ago 12 dB wouldn’t be good enough for QPSK even with some interleave and FEC. You’re getting 3 times the spectral density from it.

      1024QAM from 20 dB seriously impressive too. Again showing my age not that long ago 64QAM needed 24 dB.

  5. Avatar Amit says:

    its not clearly mentioned how they have achieved this data rate, which optical plateform is being used? more technological information should be added, to understand how its being achieved in SM.

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