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BT Extend UK Vectoring Trials to Fix FTTC “Fibre Broadband” Speeds

Friday, January 30th, 2015 (3:52 pm) - Score 9,608

BTOpenreach’s long running VDSL2 Vectoring (ITU-T G.993.5) trial, which aims to improve the performance of BT’s existing “up to” 80Mbps capable hybrid Fibre-to-the-Cabinet (FTTC) superfast broadband lines by significantly reducing crosstalk interference, has been extended to 100 DSLAMs in selected areas that will benefit from the upgrade.

At present one of the biggest and growing problems with BT’s FTTC technology is the fact that lots of active lines running in close proximity can create interference for one another (crosstalk) and, as we know, interference on a copper telephone line can reduce the speed of your Internet service.

The uptake of FTTC is naturally improving all the time and thus consumers have been noticing the impact of this, with some losing anything up to around 20% to 30% of their original line performance to the problem (this can sometimes also be confused with local ISP capacity congestion). We see the impact of this almost every week and it is a very real issue.

Mercifully the ITU came up with the solution of Vectoring (Self-FEXT Cancellation) to coordinate line signals, which works a bit like those noise cancelling headphones you can buy and thus helps to remove most of the unwanted interference.

The result of Vectoring is that FTTC line speeds return to normal / become more stable and this would also help if ever BT decided to ramp the top speed up to 100Mbps. But take note that Vectoring is really about fixing an existing problem, not boosting speeds further.

As a result Openreach has been running Vectoring trials since all the way back in 2013 (it had a few teething problems back then) and last year this was expanded into a second Phase 2 Trial (full details), albeit still initially focused on the same Street Cabinets [26, 41 and 42] in Barnet (London) and another three [12, 39 and 74] in Braintree (Essex) from the first trial.

The Phase 2 trial also tested a number of other improvements including Physical Retransmission (G.INP), Seamless-Rate-Adaptation (SRA) and an Application Specific Integrated Circuit (ASIC). Crucially Openreach last week confirmed that G.INP technology, which tackles spikes / bursts of electromagnetic interference (impulse noise) and can thus make some problematic lines more stable, is now rolling the upgrade out in a process that is “expected to take several months to complete“.

Meanwhile we’ve been hearing rumblings for the past month that Openreach might be close to a full commercial deployment of Vectoring technology, which is largely based on off-the-cuff remarks from engineers who claim to have been installing Vectoring capable hardware in other areas.

Openreach have now officially confirmed that they’ve “extended vectoring trials” to 100 DSLAMs (Digital Subscriber Line Access Multiplexer) in selected areas, although no decision has yet been taken on a commercial roll-out.

An Openreach Spokesperson told ISPreview.co.uk:

At this time, we are still very much in trial stage, and are considering whether to introduce vectoring into the network more widely. We will be consulting with all our CPs.”

For the uninitiated, DSLAMs in an FTTC setup usually exist inside Street Cabinets. Essentially they take the connections from subscribers (through Line Cards slotted into the DSLAM) and aggregate that traffic into a backbone capacity connection. Street cabinets can usually hold up to 4 or 6 line cards, which depending upon size can cater for up to 288 subscribers (per cabinet).

In other words the news that 100 DSLAMs are now being enabled for vectoring represents a fairly large expansion of the trial, although it’s difficult to be sure of the specifics without knowing precisely which type of DSLAMs are being used. We have asked for a complete list of the new trial locations but so far this has not been supplied.

We suspect that Openreach wouldn’t be going through such a long trial unless they felt, as we do, that Vectoring is a necessary upgrade given the rising problem of Crosstalk. One alternative might be to skip right to deploying Gigabit (aggregate speeds) capable G.fast technology and today’s related roll-out announcement from BT lends some support to that idea (here).

But the G.fast roll-out won’t begin until 2016/17 and it’s a much more costly / significant upgrade than Vectoring, which will take several years to complete. Never the less we did query with BT whether the G.fast announcement would have any impact upon the potential deployment of Vectoring, especially as BT have announced it before Vectoring which is already much more mature and well into advanced trials.

The reply came that BT still intends to somewhat selectively vector VDSL cabinets “as and when required to maintain network performance“, so it looks like they’ll only deploy it where a problem is identified (i.e. areas of strong FTTC uptake are thus most likely to benefit). G.fast is also vectored and so the idea is that once G.fast is deployed then VDSL Vectoring “may not be required in those areas” (you’d need to swap many of the FTTC lines to G.fast first of course).

On the consumer side there will be questions about support via existing modem and router hardware. The VDSL integrated kit supplied by ISPs should ideally already be vectoring capable, although it’s noted that some older third-party VDSL integrated routers don’t support Vectoring and a few of Openreach’s older VDSL modems will require a firmware update (some may also need to be replaced, but this shouldn’t be a huge issue).

In any case the trial, for now, will continue for a little longer, we’re just not sure quite how long that will be. It’s worth noting that G.INP, which is now being deployed, was supposed to be tested during the later stages of Openreach’s phase 2 trial (i.e. a vectoring decision can’t be that far off if G.INP is now being rolled out).

Leave a Comment
22 Responses
    1. Avatar FibreFred says:

      Already read it, don’t rate it

      For a more realistic view not one from a sole blogger:


      Just a few of many links that have good things to say about G.Fast

      I’d take the views of reknowned experts in the field over Neil (sorry Neil)

      He says its a cul-de-sac, guess what.. that’s technology for you it doesn’t last forever.

      ISDN, cul-de-sac
      ADSL, cul-de-sac
      VDSL, cul-de-sac
      G.Fast cul-de-sac

      We all know that FTTP has the most future life out of any tech , we also know the cost of it

    2. Avatar GNewton says:

      This is what Peter Cochrane said a year ago:

      “All this was so obvious way back in 1986….but ‘real engineering and economics’ has been driven out of the telecoms industry. You can’t beat physics (loss and crosstalk) and you can’t stop Moore’s Law! Mini-DSlams are an insane option! To get network reliability and resilience you have to take out electronics not put more in! To get a ‘Green Network’ you have to reduce the amount of material used and energy consumed! And Mbit/s are not enough for an obvious future rushing towards us. We have to start talking Gbit/s. But if you want sub-optimal industries and a population who just sit and watch sport on TV….just keep installing copper!

      With a copper network you need over 6000 switch site in the UK. If you install optical fibre this number drops below 70. 20,000 man in van crews goes down to 1,000, and all water ingress related faults just go away. No redo the economic argument. Go figure!”

      He’s absolutely right. But let these ISPReview forum’s BT trolls dream on, if they wake up, we can send them to Spain to learn from Telefonica or JazzTel how FTTP can be done.

    3. Avatar FibreFred says:

      Ignitionnet has already explained to you about Spain, its not a valid comparison

      Keep ignoring that tho it makes you “sound” like you know what you are on about

      Peter doesn’t like VDSL and G.Fast… another sole person, plenty of others around the globe think it makes sense.

    4. Avatar Steve Jones says:

      Yes, we know the issues. It’s one of cost (and speed of deployment). As g.fast inherently means fibre is being run very close to the properties, it’s going to be pretty simple to include GPON at every node at the same time (there’s an implication that’s what is intended). Indeed, I see no reason why the two can’t be combined into a single unit sharing a fibre (Wave Division Multiplexing means each can have “full” bandwidth). In any event, if you read the article, there’s a strong implication FTTP will be available for those willing to pay the extra to install fibre to the property. (It should be much more affordable than FPOD as it’s a much shorter install distance).

      It’s not just cost at least as important is the availability of resource and roll-out speed. It’s much more work to run fibre to every property than the initial installing of the node to support them. There are only so many people available to do this. It will be possible to roll-out g.fast much faster with the same workforce. It’s simply not possible to create a huge trained workforce in short order, let alone expect it to conveniently disappear at the end of a large scale project. Even the relatively tiny Jersey Telecom fibre rollout (now threatened with delay due to financial issues) has had problems with resourcing, and they can call on the supplementary services of companies in the UK and French markets to supplement local labour.

      A further example of roll-out resources, is the current Australian National Broadband Network (NBN) which is budgeted at the UK equivalent of £40bn+ when adjusted for number of properties (and which includes a mixture of fibre/copper hybrid as well as pure fibre) is only passing about 400,000 homes per year, or about what BDUK currently does in 2 months. At that rate, they have 15 years to go. That’s for about 93% coverage; the rest, understandably, get satellite.

      Calling the technology gfarce isn’t an argument. It’s a rhetorical debating tactic of dubious merits. Trying thinking about the trade offs involved. Just because some want 1 gbps FTTP does not mean that it’s a sustainable market at the moment, or that it can be done quickly. Just how many people sign up to the highest speeds available on VM, Gigaclear or Jersey Telecom? The answer, generally, is that people buy what they need and not necessarily best. If somebody has to wait 15 minutes rather than 1 for a 4GB download on an occasional system update as they’ve only got 40mbps (let alone, say, 250mbps g.fast), then it’s hardly a killer problem for the great majority. For those that do desparately require that magic 1gbps, that is going to be offered too.

    5. Avatar Steve Jones says:

      Peter Cochrane made one great call several decades ago (that was the use of fibre in trunk call networks and not spending money on inferior co-ax trunks). It made huge financial sense at the time as it was also cheaper, as well as being better than the alternatives.
      However, a wildly different thing to the distribution network where the costs and logistics of installation are on a wholly different scale. Installing a few 100km of trunk fibre is one thing. Running fibres to perhaps 25m premises is another thing entirely. There simply isn’t the resource to do it in a reasonable time frame, even if the money could be found.

    6. Avatar themanstan says:

      A blog by a product marketeer is just that, it is selective with what it describes.

      What BT can be seen to be doing is what most people have to do, incrementally upgrade because it´s too expensive to do in one go…

      I´d love to have started off home ownership in a 5 bed, 5 bath property… but I can´t afford that.

      I had to start small, wait for savings to accumulate and/or market conditions to be right, then upgrade. Otherwise i´d have a mortgage that I couldn´t service (like Telewest and NTL)…

    7. Avatar TheFacts says:

      Chris has no business knowledge or sense when it comes to telecomms. Repeating the same silly words and not engaging in discussion proves that.

    8. Avatar Ignitionnet says:

      The man doesn’t like alcohol, hence is clearly not a techie 😉

    9. Avatar Ignitionnet says:

      Wrong story by the way, this one’s about vectoring on VDSL.

    10. Avatar themanstan says:

      I love gin… but if you didn´t look at Chris´s post then then you´d wouldn´t have realised it´s a reply to her link…

    11. Avatar MikeW says:

      You can tell that Peter Cochrane operated in a period of little competitive threat to the GPO Telephones business. When the technically-best solution could be chosen without fear of going bust. That, when BT was starting to feel the pinch of commercialism, he was firmly hidden away in the research side.

      He found out about the going bust part more personally later… Engineers and money aren’t the best bedfellows. One reason is perfectionism.

      I know a few engineers who tend toward the perfectionist, and I tend to veer that way myself. Making technical compromises to fit the financial reality is a tricky thing to do for such people – and Peter comes over as just such a perfectionist from the engineering perspective. He does not offer a solution to the financial problems.

      Something like a fibre rollout is enough to bankrupt a company easily. As a process, it is little different from the rollout of coax by the cable companies in the nineties, and we know how thriving those companies are now. The high costs and long payback period are the trickiest elements. You need a lot of customers to come on board, and some assurance that they won’t jump away at a whim. In an environment regulated to be as competitive (cheap) as possible.

      The volume of customers required means that you must appeal to the masses, and not just the noisy few populating forums in the bottom half of the internet. Appealing to the masses, in the UK, means being cheapest. And that makes for even longer payback times.

      If someone undercuts you with a “just good enough” product, and takes away all your customers, you go bust owning a lot of dark fibre. Long payback times mean that your business is at risk for a very long period.

      B4RN works, essentially, because they have a monopoly on broadbands speeds above 1Mbps in their patch; with this, they can build an assumption of 75%+ take-up into their business plan for 15 years or more. This gives them a good expectation of cashflow. They don’t bother to touch the larger villages where competition of semi-viable speeds exists, and a 50% take-up cannot be guaranteed.

      When we’ve figured out how to reduce the risk of a national project that is likely to have a 20, 30 or 40 year payback model, then we’ll jump directly to FTTH.

      In the meantime, the current way to reduce the risk is to rollout in manageable steps – and to only move on to the next step when the market is ready for more. A 10 year rollout of FTTC, followed by a 10 year rollout of FTTdp, followed by a 10 year rollout of FTTH is much more likely.

      It might be technically imperfect, but it is financially palatable.

      When the likes of Peter Cochrane, Chris Conder and Neil Fairbrother start to include the reality of finance in their arguments, then it’ll be worth reading.

    12. Avatar GNewton says:

      @TheFacts: “Repeating the same silly words and not engaging in discussion proves that.”

      No offense, but that’s precisely what you do all the time, with your constant rhetoric and stupid questions, and your unwillingness to do your own reserch. E.g. have you ever worked out the answer to the questions raised last summer? Or is it all conviently forgotten?

      BTW.: Why do you even care to post on this forum in the first place? Why don’t you do something to get a better broadband service in your own location?

    13. Avatar Ignitionnet says:

      It should of course also be noted that B4RN haven’t paid in cash for much of the labour, it being done by volunteers or in return for shares, and have also been able to ‘sell’ ducting to local communities and interested bodies.

      Even doing this they are still running at £1k per premises passed.

      None of these options are realistically open to BT or another large company.

    14. Avatar Steve Jones says:


      It would be fascinating to know what B4RN’s installation costs would have been if they had to pay commercial rates for manpower, use of donated machinery and wayleaves. The B4RN model is very commendable, but it’s not exactly scalable to national roll-outs or use in any areas where significant road/pavement works are required.

      (It’s not actually necessary do me to make the point really – it’s pretty well exactly what the B4Rn business case says).

    15. Avatar FibreFred says:

      Even if B4RN scaled up on cost we’d be all living on the moon before it reached all of the UK, it must be years behind schedule now

    16. Avatar Ignitionnet says:

      For a description of G.fast by someone who knows what they’re talking about, read some of th papers at http://www.joepeesoft.com/Public/DSL_Corner/_Index.html

    17. Avatar MikeW says:

      The more I read documents on that page, the more I realise that Telcos see G.fast as a part of the ” fibre end-game”; that they intend (where expedient) for the very last part of copper to remain in the fibre world. Perhaps it is cheaper to leave it there. Perhaps fibre isn’t suitable for final in-building routing. Perhaps people don’t want their garden dug up.

      The whole aim is to get the fibre speeds continuing into the property without the mess/effort/disturbance.

      It is also interesting to see that one of the featured cable models is for BT’s CAD55 – 4-core copper 0.5mm. I think a lot of work has gone into remodelling the cables, including options for bonding.

      And finally, G.fast works over co-ax.

  1. Avatar Matt says:

    Interesting good to see that Vectoring is slowly reaching more and more people. Glad to see that it is happening. I was under the idea that Vectoring was required to use G.Fast fully which meant that a Vectoring rollout would happen before G.Fast but never considered them rolling out both at same time.

    1. Mark Jackson Mark Jackson says:

      G.fast needs vectoring too but it’s a separate implementation from FTTC.

    2. Avatar Matt says:

      Ah thanks for clarifying that for me.

  2. Avatar hmmm says:

    looking into it well want to get round this place and fix the fttc shite

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