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BT Trial 5.6Tbps on a Single Optical Fibre and 2Tbps on a Live Core Link

Wednesday, May 25th, 2016 (5:08 pm) - Score 2,270

Telecoms operator BT and Chinese technology firm Huawei have announced that they’ve successfully run two new fibre optic network trials, one that delivered 2Tbps (Terabits per second) over a 727km live core network link (London to Dublin) and another that pushed 5.6Tbps via a single optical fibre.

The developments mark a leap forward from the operator’s last closed network trial in October 2014 (here), which at the time claimed to have harnessed a “record spectral efficiency” of 5.97bit/s/Hz in order to deliver super channel speeds of 3Tbps (Terabits per second) over an existing 359km long fibre optic link using commercial grade hardware and software in a real world environment.

Crucially the latest 727km long 2Tbps trial sees BT successfully applying the same technology to their commercial fibre link, which is carrying live customer traffic between London and Dublin. Meanwhile the new 5.6Tbps trial is more akin to the original closed network test conducted in 2014, although it’s an example of what we could be seeing in the near future.

The clear advantage of upgrades like this is that they can be done without needing to lay new fibre optic cables, which is usually a heck of a lot cheaper.

Howard Watson, CEO of BT Technology and Service, said:

“BT scientists built the first commercial single mode optical fibre link back in 1984 and the BT Labs remain at the forefront of photonics research more than thirty years later.

The core network is the superhighway of the internet. It’s important that our core networks keep pace with the growth in bandwidth demands driven by take-up of high-speed fibre broadband, HD content, 4G smartphones and tablets and in the future, 5G services.

So we’re investing in our core, as well as in high-speed access technology such as fibre broadband, to make sure there is no capacity crunch and deliver the best possible speeds to customers.

These landmark trials show that we can easily turn up the dial to deliver the speeds needed in our core networks to stay well ahead of rising customer demand.”

Sadly BT doesn’t yet apply the same logic to domestic connections, where the copper cables in their hybrid fibre FTTC and G.fast broadband diet are still the main limitation and require a lot of upgrading in order for the services to keep pace with rising demands.

Deploying pure fibre optic cables to individual premises would be a lot more future proof and BT does intend to deliver over 2 million ultrafast Fibre-to-the-Premise (FTTP) lines within the next few years, although that’s only a small part of their overall network.

Unfortunately going further with FTTP would also take many years longer and require many billions more in investment, which is very difficult for the operator to justify to their shareholders.

Other Technical Trial Facts

  • The 2Tbps trials exploit commercial flexible grid hardware and real-time flexible rate 64GBaud transponders. 64GBaud optical technology runs at twice the electrical speed of current deployed core optical network optical signals and is one of the key enablers for high-speed, long reach optical transmission.
  • The live trials were conducted over a 727km commercial flexible grid optical core link between London and Dublin, based on Huawei’s OSN 9800/8800 and iManager U2000 platforms, carrying live 40/100G customer traffic. The link includes a 133km long unrepeatered submarine cable link from Dublin to Holyhead.
  • The trials demonstrate, for the first time, the successful operation of real-time 64GBaud flexible-rate transponders allowing all-optical, long reach (unregenerated) superchannel transmission, with low latency.
  • In addition, by exploiting flexible rate transponders, BT successfully demonstrated fast capacity turn up (or network upgrade) equivalent to ~2Tbps in one minute.
  • BT and Huawei also successfully demonstrated a record real-time 5.6Tbps optical superchannel over a closed loop network running between the BT Tower and Adastral Park. This comprised 28 x 200Gb/s (64GBaud/QPSK) sub-channels, bundled together to provide combined capacity, achieving highest capacity and spectral efficiency.

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By Mark Jackson
Mark is a professional technology writer, IT consultant and computer engineer from Dorset (England), he also founded ISPreview in 1999 and enjoys analysing the latest telecoms and broadband developments. Find me on Twitter, , Facebook and Linkedin.
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21 Responses
  1. adslmax Real says:

    BT should have move forward with true fibre to the house by now! The old fashion copper from fibre cabinet are not future investment.

    1. Pete says:

      “Unfortunately going further with FTTP would also take many years longer and require many billions more in investment, which is very difficult for the operator to justify to their shareholders.”

      There the problem right there. BS about billions needed and crying about shareholders, if rural communities in the north of the UK can organise and fund 1Gbps FTTH why cant BT, their an embarrassment to the UK. I’m glad Google have show some interest in bringing their FTTH/P solutions to the UK.

    2. fastman says:

      adsl max — there is no widespread case for FTTP in any shape of form and even where this is significant FTTP coverage there are very few service providers who want to sell it (6 out of 530 I think) !!! as its more expensive for the service provider and means a reduced margin

  2. Colin says:

    Do they ever trial anything or make a single announcement that actually becomes reality?

    1. FibreFred says:


      Yes lots and this isn’t about fibre to the home/house/premise adslmax Real its about re-using existing connectivity in the core with much great throughput, all good stuff.

    2. Colin says:

      ADSL speeds never matched what they initially claimed they would be, the first products were only 512k, it was another 2 years before it made the “trial” 2Mb speed
      ADSL2 LLU beat them to that by some years
      FTTC was the rollout spose to be done by now, multiple delays, dubious coverage claims which vary month to month
      FTTP never rolled out in the numbers claimed initially.

      If they could deliver products that match the fantasy they portray they would actually be a great provider.

    3. FibreFred says:

      You asked if they trial anything that becomes reality

      Yes they do

      As you will never use these core products I’m not sure why you are concerned

    4. Steve Jones says:

      So what bit of

      “BT scientists built the first commercial single mode optical fibre link back in 1984″

      Did you have trouble understanding (just as one example)? Every product that has appeared will have been trialled at some point.

      Really, your point is extremely silly. Every organisation deploying technology on a large scale of technology in the world trials things first. If companies don’t test and trial things, then it’s just experimenting on customers and disasters happen.

      Smaller scale organisations can afford to experiment a bit more in roll-outs as they have the flexibility to adapt things as they go along. That approach simply doesn’t scale up. Also, smaller companies often rely on the proving work done by the majors. Smaller companies did not develop or test the technology. DSL, for example, came out of the labs and specification processes of members of the ITU. The entire ratification process for standards comes via collaborative working of many such operators and equipment suppliers. Those telcos with major testing labs are owed something of a debt by the many companies that use the results of such work.

  3. adslmax Real says:

    Why do BT trial at all the times? Stop waste your time of trial things and act fast!

    1. TheFacts says:

      Please explain what you mean.

    2. Ignition says:

      So that they avoid acting fast, releasing products that don’t work properly, that their systems don’t properly support, that their staff and contractors haven’t learned to install properly it at all, and that their customers, the CPs, don’t properly support.

      That’s pretty much it really.

      That and PR. Running trials of things you never intend to actually release or at least release widely, AKA Fibre to the Press Release, is pretty common too.

    3. GNewton says:

      @Ignition: While I agree trials are needed it is also a fact that many of BT’s so-called trials come many years late, and in cases it would have made more sense simply to copy newly introduced technologies already widely available in other countries. Trials can be useful, but there is no need to re-invent the wheels, or to do these excessive PR exercises.

    4. TheManStan says:

      That trivializes the fact that other countries have completely different hardware setups. The knock-on effects of how you integrate dissimilar hardware (upstream/downstream) are substantial.

      BT is heavily regulated, with respect to pricing and failure to trial appropriately would have implications on the SMP remedies related to this such as charge controls. These charge controls are related to costing that BT provide, so hence the conservative approach.

      OFCOM would have to relax regulations if BT were to roll-out tech/products faster, but we all know that OFCOM take forever and are even more conservative…

    5. MikeW says:

      Are you saying BT shouldn’t research these things? Or that they shouldn’t trial and test them out? Or just that they shouldn’t publicise the results of either?

    6. TheFacts says:

      Tesco are trialling contactless payments in a few stores. What’s not to know?

    7. Karl says:

      “Running trials of things you never intend to actually release or at least release widely, AKA Fibre to the Press Release, is pretty common too.”

      Soo True.

  4. Ignition says:

    I’m a bit confused. QPSK is 2 bits per symbol. How were they managing to get 200Gb/s out of 64Gsym/s if they were running QPSK?

    Seems more likely they were using DP-QPSK.

    This follows a trend of lower order modulations and larger bandwidths. Using DP-QPSK rather than the 16QAM used in the aforementioned trial means lower SNR requirements so better reach for the same transmit power.

    1. MikeW says:

      I get the impression DP-QPSK is suited to longer distances – which is perhaps why they wanted to use a London-Dublin fibre.

      I have to say that I’m impressed that the two polarisations will stay close enough to 90° apart, and not stray from that with minute variations in refraction.

  5. Darren says:

    2Tbps is a better upload speed target 🙂

    1. Ignition says:

      Let’s perhaps get to 1/100000th of that level first, then work from there.

  6. GrammarNazi says:

    Stop using “premise” for a single property, it’s not what you mean. It’s always premises, whether a single property or indeed multiple properties.

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