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[Bowdon]

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

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. 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.

[Weaver]

Wonder what it's like over 100m say.

Are we really so desperate to avoid FTTP? And we would still have to worry about the unreliability of copper and the problems with RF interference and crosstalk (although there is G.Vector).

[Chrysalis]

Accountants will be desperate yes, every penny saved is important to them.

Even if we talking about the final say 30m of copper, if you look at the cost of say 10 million homes where 30m of copper does not need to be replaced, the savings will be big enough for an accountant to consider important.  Copper can be made very fast providing the distance is short enough and this newest announcement relies on very short copper runs.  BT will sweat copper as long as it can.

I assume everything from g.fast onwards will be vectored.  Meaning crosstalk is mostly mitigated.

However in many areas 30m of copper will actually be 30m of ali, as these runs gets shorter, the % of ali on a line in ali areas increases as most runs of ali are at end of loops on the property side. Whether it actually is an issue tho I have no idea, as I understand it ali is as good as copper when vectoring is in play and providing there is no joints, the downsides of ali are supposedly crosstalk and their corrosion on joints.

[Weaver]

What would the accountants feel about the maintenance costs of 30m of metallic path facility? Deferred costs, for one thing. And there is the lack of future-proofing, but then high frequency data over metal does keep on surprising us.

[Chrysalis]

Maintenance on the line near the home should be low as with the short length and proximity to the home any fault finding should be a simple process.

It will be several years at least I reckon before BT gets to this stage, they will only deploy more fibre when they absolutely need to.

[Weaver]

And short lines means the absence of joints and hopefully no lightning damage, so all a plus for low maintenance costs.