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New nbn XG.Fast Broadband Tech Trial Delivers 8Gbps via Copper Lines

Tuesday, October 18th, 2016 (8:12 am) - Score 2,142

A new trial of the future XG.FAST technology, which could one day replace Openreach’s forthcoming G.fast based ultrafast broadband service, has beaten last year’s BT trial by pushing a peak aggregate speed of 8000Mbps over 30 metres of twisted-pair copper (BT achieved 5.6Gbps at a similar distance).

As a quick recap, XG.FAST is being designed (it’s not yet an official standard) to follow-on from the more familiar G.fast technology that will next year be rolled out across the UK by BTOpenreach (details). Both technologies follow a roughly similar deployment approach to the current ‘up to’ 40-80Mbps VDSL2 based Fibre-to-the-Cabinet (FTTC) service that dominates our market.

In all of these scenarios a high capacity fibre optic cable is run to a local distribution point (usually a street cabinet or smaller node on top of a telegraph pole / underground etc.) and then the remaining connection into homes is done via the existing twisted-pair copper cable. The copper connection is where VDSL2, G.fast or XG.FAST comes into play.

Last year saw BT and Alcatel-Lucent conduct a joint test of the future XG.FAST (G.fast2) technology, which managed to deliver aggregate broadband speeds of 5.6Gbps (Gigabits per second) over just 35 metres of copper cable and 1.8Gbps at 100 metres (here). At 35 metres you’d get a little over 1Gbps+ on G.fast (falling to c.700-900Mbps at 100 metres) and easily max out VDSL2.

By comparison the latest lab trial, which was conducted by Nokia and nbn in Australia (North Sydney) during September 2016, achieved a peak aggregate speed of 8Gbps over 30 metres of twisted-pair copper (similar to BT’s network) and 5Gbps over 70 metres. Clearly an improvement, although this is unsurprising as the technology is still very much in its R&D phase.

We should add that Deutsche Telekom conducted a similar test with Nokia earlier this year, which achieved an aggregated bandwidth of 11Gbps+ on two bonded pairs of Category 6 cable at 50 meters in length (NOT comparable to the above test). But they also ran similar tests using standard drop cable, which achieved aggregate rates that exceeded 8Gbps over 50 metres.

Dennis Steiger, CTO of nbn Australia, said:

“Although XG.FAST is still in its very early stages of development the lab trials we have conducted demonstrates the huge potential that the technology offers.

XG.FAST gives us the potential ability to deliver multi-gigabit speeds over copper lines – virtually on a par with what is currently available on Fibre-to-the-Premises – but at a lower cost and time to deploy.

While our core goal remains to connect 8 million premises to the nbn by 2020 we are keeping a close eye on new technologies like XG.FAST to ensure we can meet the future bandwidth demands of Australian broadband users.”

Unlike today’s default VDSL2 setup in the UK, both G.fast and XG.FAST contain improvements to cancel out troublesome interference as standard (e.g. Vectoring, G.INP, SRA, FRA) and that’s good. Mind you there is a big caveat in all this. While VDSL2 can harness 17MHz+ of spectrum, G.fast needs 106MHz+ and XG.FAST gobbles up to a hefty 500MHz (at that level there’s also the risk of interfering with other devices).

The extra spectrum is all well and good, but it also means that in order to get the best speeds you have to bring the fibre optic cable increasingly close to homes (the signal weakens very quickly on longer copper lines) or you drop the top speed significantly in order to tolerate a greater distance (i.e. reach more premises for less cost). Check out our Broadband Technology page for more.

At present BT hopes to deliver around 300Mbps over 300-350 metres of copper line with G.fast and this should give them a reasonably good level of coverage, on the cheap, when deploying from the side of existing PCP street cabinets. However it remains to be seen what upper tolerances XG.FAST could cope with before the signal breaks down, but it’s clearly happiest when it can sit much nearer to your home than G.fast (i.e. XG.FAST may need a much more fibre rich FTTdp deployment).

We should add that Nokia was recently chosen, alongside Huawei, as one of the two key equipment partners for BT’s roll-out of G.fast in the United Kingdom. However we’re unlikely to see XG.FAST anytime soon; it still has a long road of development, trials and standards setting processes to travel.

Mind you the most future proof approach would simply be to forgo all this extra complexity and roll-out a pure fibre optic (FTTP/H) network, assuming somebody is willing to pay for that and conduct it without damaging the altnet competition outside of dense urban areas.

Leave a Comment
34 Responses
  1. Avatar Ignitionnet says:

    500MHz over unshielded cabling, potentially on poles. To think people thought the odd bit of signal leakage from CATV networks was bad.

    1. Avatar Data Analysis says:

      “500MHz over unshielded cabling, potentially on poles.”

      Is cables on poles even rated at that? Isn’t it similar in spec to something old like CAT3?

    2. Avatar MikeW says:

      No, twisted-pair won’t be “rated” at these frequencies or speeds … but that just means no-one envisaged the kind of demodulation hardware being put into the likes of G.Fast and XG.Fast. No-one had the means to create a rating for that hardware.

      The “rating” of a cable has an implicit dependency on the hardware used to drive the cable.

      This can be seen with cat-5e cable: Everyone “knows” that Cat-5e is “rated” for gigabit ethernet. However, that too is getting new demodulation hardware … and the same cable can suddenly now handle 2.5Gbps and 5Gbps.

    3. Avatar MikeW says:

      Incidentally, the first steps toward creating G.Fast was a characterisation of existing cables, followed by the creation of models/predictions for cable behaviour. This, I guess, is a “re-rating” of the cable.

      Some of the work can be seen back in 2010-2011:

    4. Avatar Data Analysis says:

      “This can be seen with cat-5e cable: Everyone “knows” that Cat-5e is “rated” for gigabit ethernet. However, that too is getting new demodulation hardware … and the same cable can suddenly now handle 2.5Gbps and 5Gbps.”

      If you mean this…

      A. Thats because it will be at a lower signalling rate
      B. Its only good for around 100M so a solution similar to that wont help with BT and real life cable several Kilometres long will it. Also probably why this only managed it over 30M of cable.

      Cable as ignitionnet hints at will leak signal. And that will happen no matter what clever gizmo equipment you connect to it.

      Even more so on cables decades old like BTs which have had joins, repairs, decaying insulation and more issues.

      Its another nice day dream to have though.

    5. Avatar MikeW says:

      Another pointless tangent.

    6. Avatar Gordon says:

      How is pointing out statements in a story a tangent?

    7. Avatar Evan Crissall says:

      MikeW was hauled up in 2013 and again in 2014 for inventing factoids over average dropwire length; a critical factor in G.Fast deployment. Here we are in 2016 and he’s still inventing!

      According to Openreach, the maximum length of a DW14 (4pr) dropwire is 55 metres. While maximum length of DW10 (2pr) dropwire is 68 metres.

      So how does Mike “if-I-can-remember-correctly” Wilcox arrive at “an AVERAGE dropwire length of nearer 60 metres” and with 20% of dropwires, so he claims, being 70 metres or more?

      For fear of rehashing old rebuffs, here’s how MikeW was scolded three years ago, for similar shenanigans:

      “If you have nothing to contribute rather than blindly defending an organisation with out researching anything it’s probably best you do not bother.”


      And again in 2014, the riposte:

      “The rest of your made up figures i’m not even going to bother with.”


      How can anyone be so consistently wrong?!

    8. Avatar New_Londoner says:

      Presumably you’ll be applying this new found vigour for accuracy to pronouncements by Jeremy Corbyn too? 😉

    9. Avatar Data Analysis says:

      “How is pointing out statements in a story a tangent?”

      Dunno there seem to be one or two that do not like other views or actual analysis here though.

  2. Avatar DTMark says:

    This appears to be a solution for very small blocks of flats.

    I’d have thought that this tech might be of more interest to Hyperoptic than BT given that the former does FTTB/copper.

    1. Avatar MikeW says:

      Or for the top of poles in a terraced street.

    2. Avatar DTMark says:

      Anyone care to hazard a calculation of the number of “boxes” that would need to be installed to get within 30m of, lets say, 80% of premises in the country?

      You’d have to get the fibre to the poles first. If there are poles. Otherwise, underground.

      It’s not going to happen, is it.

    3. Avatar TheManStan says:

      Wouldn’t 100M be relevant? 1.8 Gbps at 100M would be plenty for anyone…

    4. Avatar MikeW says:

      IIRC, back in early G.Fast testing, BT reported that 20% of drop lines are less than 20m, and a “typical” one is 35m. 80% are less than 70m … so I guess this is the reach you need.

      There are, apparently, around 4 million DPs in the UK. 50% overhead, 25% underground.

    5. Avatar Chris P says:


      Hyperoptic just install a switch in the basement of the flats and run cat 5 or 6 to the dwelling. Cat 5/6 etc can run much longer than 100m, the 100m limit is due to the length of time the Ethernet protocol waits to listen for collisions on half duplex networks, the problem is irrelevant for full duplex.

    6. Avatar DTMark says:

      The only way in which I can see this happening is organically, which is to say, on demand.

      We’re on a lane with 5 premises fed by a minimum cable length of about 1.2km of ancient old aluminium or copper, so VDSL is not an appropriate technology. That’s suited to maybe the 20 or some premises near enough to the cabinet.

      Over a period of about 3 months I think there were 11 visits to the pole that feeds out house – I’m guessing, from the comment “I’ve swapped out the dropwire and it’s still not fast enough for the ****ers”, to try to find a decent pair for one of our neighbours.

      This involved cherry pickers on multiple occasions, two or three BT vans, up to half a dozen people standing around.

      And after all of this the customer could well have told them to shove the contract if all the pairs were bad. They must be nearly 100 years old now.

      If instead, on order, they’d dragged fibre another 600m or so nearer the premises, and popped a G.Fast box on the pole, they might have ended up with a happier customer at lower cost and have built something for the future.

      And that isn’t going to happen either, is it 😉

    7. Avatar MikeW says:

      Most of the phone network was deployed in the 60’s-80’s, especially the access network. If aluminium is around, then it is more likely to be late 60’s into the 70’s.

      If your cables are 100 years old, the setup would look something like the first 3-4 photos on this page, with open wires and insulators…

    8. Avatar DTMark says:

      Having just angled a look out of the window it doesn’t really look like any of those. It does have steps to climb but these days I guess health and safety means a cherry-picker is used. I once read that telephone engineer is one of the most dangerous jobs. Most of the poles have big black boxes on them which I think are DACS boxes, probably redundant now.

      Circuitry in the house is from before 1981 (?) – the splitter (star configuration), ‘coffin box’ et al, full of dust and dirt and looking ancient and the drop wire has what I think is a repaired section – a cylindrical black thing. It’s no wonder that lines don’t perform in the real world as they do in the lab.

    9. Avatar Data Analysis says:

      “Wouldn’t 100M be relevant? 1.8 Gbps at 100M would be plenty for anyone…”

      It doesn’t work like that the longer the cable the more loss you have. Not an equal amount per metre.

    10. Avatar TheManStan says:

      @Data Analysis

      Which is why I quoted the figures given in the article rather than trying to guess…

      100M between “boxes” and property is more rational/economical engineering solution than trying to get a “boxes” at 30M to each property which DTMark had suggested

    11. Avatar Data Analysis says:

      The story states…
      “At 35 metres you’d get a little over 1Gbps+ on G.fast (falling to c.700-900Mbps at 100 metres)”

      No idea where you got “1.8 Gbps at 100M” if you mean the statement in the other news item this one links back to, then that clearly states that 1.8Gbps was an “”aggregate”” speed.

    12. Avatar TheManStan says:

      The last bit of this section in the article…

      “Last year saw BT and Alcatel-Lucent conduct a joint test of the future XG.FAST (G.fast2) technology, which managed to deliver aggregate broadband speeds of 5.6Gbps (Gigabits per second) over just 35 metres of copper cable and 1.8Gbps at 100 metres (here).”

    13. Avatar TheManStan says:

      What’s wrong with aggregate speeds? It’s just averaged, which is usual for any speeds from this type of technology…

    14. Avatar Data Analysis says:

      Nothing wrong with an aggregate speed measure, the 35 metre figure of 5.6Gbps was not an aggregate(average) though was it?

      As pointed out initially… It doesn’t work like that the longer the cable the more loss you have. Not an equal amount per metre.

      Which it appears they have done to reach that aggregate of 1.8Gbps at 100 metres.

      Or in simple terms to get their average (aggregate) divided the 35 metre figure of 5.6Gbps by roughly 3 to get a rough 100M guesstimate… or as they call it “”aggregate””) of 1.8Gbps.

    15. Avatar New_Londoner says:

      To clarify, “aggregate” as used above does not mean either average, estimate, guesstimate or extrapolation. It does in fact refer to the sum of the upload and download speeds, bearing in mind you can increase either at the expense of the other – indeed the latest developments from Sckipio will do this dynamically to adjust to suit your usage.

      Why estimate performance at 100m when it is simple to test?

    16. Avatar Gordon says:

      conjunction or collection of particulars into a whole mass or sum; total; combined:

      a sum, mass, or assemblage of particulars; a total or gross amount:

      to bring together; collect into one sum, mass, or body.
      to amount to (the number of):
      to combine and form a collection or mass.

      Yep totally different meaning 😀

    17. Avatar Data Analysis says:

      To be fair perhaps English is not the first language to some respondents or to those that release news stories.

  3. Avatar New_Londoner says:

    This is a very encouraging development. Noting the above comments about reach, let’s not forget that similar distance limits originally applied to G.Fast and now 300Mbps+ at 300m seems possible. Given it’s still very early days for the technology, I think it’s reasonable to expect that the performance will continue to improve, with higher speeds possible at longer distances.

    My prediction is that XG.Fast will provide a viable upgrade option for the current G.Fast pods well within 5 years.

    1. Avatar Data Analysis says:

      “G.Fast and now 300Mbps+ at 300m seems possible.”

      What happens at 600M and 900M to that speed?

    2. Avatar Evan Crissall says:

      @New_Londoner: “My prediction is that XG.Fast will provide a viable upgrade option for the current G.Fast pods well within 5 years.”

      What current G.Fast pods?! You’re living at least a decade in the future, New_Londoner. More rogue thinking.

      First get G.Fast installed – conservative estimate: 2025. Sweat that for maximum time. Then belatedly think about XG.Fast. Bringing us up to 2035.

      Telecoms in Britain, by then, 40 years behind rest of OECD.

    3. Avatar New_Londoner says:

      Au contraire comrade, I’m pretty sure that the first G.Fast pods are due to go live within the next six months, so you’re the best part of a decade too pessimistic! As I don’t live in Balham or Upton Park though, I expect I’ll have to wait for a year or so before upgrading, certainly anticipate being amongst the 10 million premises slated for coverage by 2020.

  4. Avatar New_Londoner says:

    No idea, my interest is in performance at 300m given this is the approximate distance from my home to the cabinet. No doubt a search on google will give you a view of current G.Fast performance over distance, although the progress made in the last 12 months or so suggest reach should continue to improve.

    1. Avatar Data Analysis says:

      I hope that you do manage a reliable 300Mb at 300 Metres distance 🙂 If that does happen for everyone at that distance then it will be good.
      I could not find any information on how it performed at distance such as 900M hence the query. As for furthest reach i did not know there was a limit on that already, and they were working on improving it.

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