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UPD BT Confirm UK Trial Areas for Superfast Broadband FTTC Vectoring Tech

Wednesday, April 24th, 2013 (8:01 am) - Score 3,954

BTOpenreach has confirmed to ISPreview.co.uk that the first locations to trial its FTTC (VDSL2) Vectoring (ITU-T G.993.5) technology in the United Kingdom, which could eventually help ISPs to deliver download speeds of up to 200Mbps (Megabits), will take place in Barnet (London) and Braintree (Essex) in England.

Vectoring technology can work in a single copper pair and is designed to remove interference (crosstalk) from the line by using a similar method of “noise cancellation” to some modern headphones. Otherwise speeds become slower as you get further and further away from your local street cabinet (FTTC only takes a fibre optic cable as far as this cabinet and then uses the existing copper line to reach your home) .

It is essentially a mathematical process that “calculates the interference between all pairs in a binder, based on the actual signals, and will use this information to generate a noise cancellation signal on each pair“.

But according to BT’s Head of Access Platform Innovation, Kevin Foster, the technology will be used more as a “speed enabler” than a speed booster. In other words headline speeds, which currently stand at 80Mbps for FTTC (though another rise to 100Mbps+ is anticipated), are likely to stay the same but those on longer copper lines could get faster speeds than they do today.

Kevin Foster revealed the information during his speech at the DSL Conference in Paris (France) and ISPreview.co.uk quickly moved to verify the development with Openreach. The operator revealed last week that it was planning to test the capabilities of Vectoring as part of a trial involving its CP customers during Summer 2013 (here).

An Openreach Spokeswoman told ISPreview.co.uk last week:

It’s far too early to say whether we will be deploying vectoring in our network as any decision will be dependent upon the outcome of the trial.‪ However, we believe vectoring has the potential to be a cornerstone technology of FTTC deployment in the future.

Customer feedback and the latest figures from Ofcom suggest that our fibre products are performing very well and, as you would expect, we’re continually evaluating emerging technologies aimed at further enhancing performance.”

Sadly precise details about what implementation BT will be using remain unclear and Openreach will not reveal anything further until ISPs have been advised of its trial plans, which will take place sometime over the coming weeks. Vectoring will also cost money to deploy, although the investment is not expected to be too significant.

Estimates of what performance improvement we could expect to see tend to vary and there’s no accounting for the impact of a real-world environment. But with BT’s current 17MHz profile (17a) for FTTC it’s perhaps not unreasonable to expect that speeds of up to 100Mbps could be possible at up to 500 metres from the street cabinet, with up to 50Mbps being possible at around 900m and 40Mbps at up to 1200m (performance boosts of around 25% or more but very variable).

The performance could also be further increased by bonding several FTTC lines together, although that would be very expensive for home users. Similarly if BT were to increase FTTC’s spectrum allocation to 30MHz (possible but there are still some problems to overcome) then some estimates predict that download speeds of up to 200Mbps might be possible at distances of 300 metres from your cabinet.

In reality we’ll have to wait and see what the trials reveal before knowing what to actually expect and as usual the performance may be a lot lower than the best estimates.

UPDATE 26th June 2013

More details about the trial roll-out areas, dates and plan (here).

Leave a Comment
10 Responses
  1. Michael says:

    I had always assumed that the 30Mhz profile was only intended for Fibre to the Basement deployment, not FTTC, where you would be using internal building copper distribution.

    If 30Mhz is being considered for external plant copper I presume there would be lots of caveats.

    Also I seem to remember that since December 2012 the BT Suppliers Information Note (SIN) required any UK VDSL2 CPE deployments to be 17a Vectoring Ready via line software download – so I guess all CPE deployed in 2013 will already be sitting there ready.

    1. Mark Jackson says:

      It really depends upon the network environment, although all the documents we’ve seen suggest that it doesn’t have to be strictly for FTTB. In any case I am currently inclined to assume that BT will not do 30MHz with today’s vanilla FTTC solution but.. never say never. Going back a few years I recall a lot of people saying that BT would never do VDSL as well. I’m sure that they’re at least still looking at what can be done with the band plans.

      Right now what we know for a fact is that Vectoring will be progressed to trial and there’s a lot of support behind it, so I’d be very surprised if it didn’t end up playing a part (unless real testing shows a bigger than expected problem of cost or fails to overcome some other technical obstacles). So for now that’s the focus.

    2. MikeW says:

      I tend to agree – that 30a will be left for specialist cases (such as MDU) rather than widespread deployment, and agree with Michael that the message in the SIN is a big indicator that this is going to hold for quite a while.

      The only doubt nagging at my mind is the same one that asks why BT consider vectoring as a speed enabler. If it is indeed to limit headline speed boosts for the short lines, in preference to the longer ones, then use for 30MHz would do the same thing.

      If the short line modems, who could use 30MHz, all chose to put their bandwidth within the upper frequencies, the distant modems would encounter less competition at the lower frequencies. Though the need to do that assumes that vectoring is less than perfect, and leaves *some* noise behind.

  2. Bob says:

    Vectoring isn’t going to happen any time soon for BT. Vectoring really only works when applied to the entire VDSL chassis, and if multiple chassis; then cross interlinked. I know that the ECI equipment (which makes >30% of the installed base as of last summer) doesn’t support vectoring. Don’t _think_ Huawei does either. As such I can’t see BT ripping out their investment in the current technology until such time as people complain enough so that it becomes a political issue again, or a competitor looks to enter the market.

    Trials will take a while to complete, and so I can’t see any equipment being installed as standard until 2014. By then allegedly over 70% of the UK shall already have the current generation of kit. So vectoring is likely to only be provided for the last 30%.

    1. Chris says:

      Bob this depends on what dslams they using.

      It seehs the HG dslams do support vectoring, the question is then left on ECI, are bT using the ECI M41 or ECI V41. Can ispreview find this out? The M41 doesnt have vectoring, the V41 does, a guy who claimed to be part of 21CN design said they using V41. This would indicate the equipment is vectoring capable. Are the trials on both ECI and HG or just one vendor?

    2. Mark Jackson says:

      We’ll be able to ask this once the trial details have been set out in the next few weeks.

    3. MikeW says:

      Huawei don’t make much of a noise about vectoring, or describe it in their products, do they?

      The one exception is when they talk about their “node level vectoring.”

      Their descriptions suggest that “system level vectoring” depends on the addition of specialist cards that include the vectoring DSPs, so the process is offloaded from the standard linecards. NLV builds on the SLV components.

      So it looks like the Huawei’s are going to need the addition of at least one card, if they’re going to be able to vector all lines together.

      Is there room in the shelf?

      BTW – Huawei’s vectoring is rated somewhat higher than ECI’s, by some guys who measure vendor competence. The summary is here, but the report costs $$$

      Recent: http://broadbandtrends.com/yahoo_site_admin/assets/docs/BBT_VDSL2Vectoring_12300v1_Summary.33434333.pdf


    4. LJ says:

      There is a research paper out there that says vectoring benefits even un-vectored lines on a separate cab because part of vectoring process involves reducing the line gain and therefore reduces the amount of noise a pair generates.

      The gains may not be quite as huge as if every line was vectored, but to say it’s pointless or that it won’t happen any time soon is inaccurate. If the benefits are seen on the trails, it’s likely they will go forward with the upgrades sometime next year.

  3. MikeW says:

    The bit on “speed enabling” is interesting, if we follow the logic through to the consequences. Very thought provoking.

    In fact, I could handle it if they chose to make no headline change at all, but managed to get the longer distance customers to higher speeds instead.

    The first time I came across the use of Vectoring as a means for reducing power was in a paper that perhaps focused on the environment more than absolute technology advance: “Greening the copper access network with dynamic spectrum management”. It is also almost the only one on vectoring that shows power graphs rather than speed graphs!

    I like the way they describe one of the techniques they advise against: “Zap your neighbour first”.

    Incidentally, this paper is one that gives one of the simplest explanations I’ve seen why the kind of DLM techniques we now see in FTTC (speed banding) is preferred to altering the noise margin.

  4. Darren says:

    Well I never thought I’d see it, I didn’t think BT would care about bringing up the speed of longer lines with the availability of FOD. Maybe there are a lot more longer d-sides than they would care to admit, or a lot more underperforming ones.

    Seems like their using Vectoring as an alternative to installing more cabs to shorten the longer d-side runs.

    Also seems like it wouldn’t be a global rollout, with only selected lines being vectored.

    If applied globaly vectoring should make quite a difference to my cab, which is at the begining of a long road and serves about 600 properties. At several points the distance hits 1200 Metres down the side roads. It’s mostly Ali round here too which probably doesn’t help, my sync is 77678 at 300 Metres.

    I’ll be very interested to see what vectoring can acheive if it’s rolled out, which looks likely, the question is to what extent.

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