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Author Topic: ADTRAN and BT Reasearch G.mgfast – 10Gbps Broadband Down Copper Lines  (Read 778 times)

Bowdon

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http://www.ispreview.co.uk/index.php/2017/08/bt-adtran-reasearch-g-mgfast-10gbps-broadband-copper-lines.html

Quote
Researchers from ADTRAN and BT are working towards conducting the first lab trials of G.mgfast technology in 2019, which could become the successor to today’s hybrid-fibre G.fast technology and one that might conceivably push broadband speeds up to 5-10Gbps over traditional copper lines.

At present Openreach’s deployment of G.fast (ITU G.9700/9701) in the United Kingdom is being marketed with a top speed of 330Mbps (50Mbps upload) and is largely being deployed from existing PCP street cabinets, which makes it very quick to install and cheap to roll-out. The current aim is to reach 10 million premises by 2020 and there’s long been talk of top product speeds hitting 500Mbps by around 2025.

The G.fast standard can harness up to 212MHz of radio spectrum (Openreach’s live network current uses 106MHz) and peak speeds of 2Gbps (aggregate) are theoretically possible via the latest amendments, albeit only over extremely short distances. One recent FTTdp + G.fast trial in the UK delivered 1.66Gbps over 40 metres of copper line, although Openreach would be happy with 300Mbps at 350 metres from a street cabinet (if they can hit it).

This sounds like some good technology. But I think they have gone down the path to nerdville. The time of copper lines is gradually coming to an end. For this type of technology, and the current trial of G.fast, to have a big impact at all they need to push it out to pods on poles/manholes. Sadly until BT/OR manage to get the pods out there then G.fast is going to be severely restricted imho.
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Ronski

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Re: ADTRAN and BT Reasearch G.mgfast – 10Gbps Broadband Down Copper Lines
« Reply #1 on: August 26, 2017, 11:07:18 AM »

But there is benefits, if pushed out to pods on poles and in chambers then they can still utilise that copper connection which runs into the house or flats, especially if underground fed. Therefore no digging up drives, running new cables into peoples properties etc.
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Chrysalis

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Re: ADTRAN and BT Reasearch G.mgfast – 10Gbps Broadband Down Copper Lines
« Reply #2 on: August 26, 2017, 12:00:24 PM »

Find myself agreeing with Bowden, they seem to be trying really hard to push out incremental reductions in copper vs ditching it in one go using FTTP, however I doubt there is much saving when you have to reduce the copper length to 50m. As at that point you almost at the front door step anyway.

I also think openreach need to stop been so stubborn over network rearrangement, many properties already have fibre running very close to them but that fibre is just feeding a cabinet, perhaps not even their own cabinet, which of course brings me to another point, someone can be 20m away from a cabinet but again due to lack of network rearrangement they get served from a cabinet 500m away instead.

So fibre could get re purposed for FTTP without digging up any more roads or pushing through new fibre, speeds could be increased in various places just by network rearranging, speeds could be increased via VDSL2 30MHZ and vectoring which only needs dslam swapouts, some of the decisions just seem nonsense. I think ignition has mentioned bonding which is another option although I am not a big fan of that option unless they dont charge line rental for the second pair.

Now if advertising regulations changed it could change BT's thinking overnight, I keep hearing stories about the ASA changing the guidelines to something better, but its not happening, something seems to be holding it back which is I assume the telco's fighting over it.

e.g. if it changed from 10% to 50% customers needing to hit the speed, then g.fast would suddenly become obsolete by the marketing guys.
« Last Edit: August 26, 2017, 12:03:02 PM by Chrysalis »
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kitz

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Re: ADTRAN and BT Reasearch G.mgfast – 10Gbps Broadband Down Copper Lines
« Reply #3 on: August 26, 2017, 07:55:15 PM »

they seem to be trying really hard to push out incremental reductions in copper vs ditching it in one go using FTTP, however I doubt there is much saving when you have to reduce the copper length to 50m. As at that point you almost at the front door step anyway.

That in part has always seemed to be on the agenda.  Cabs then DPs so I dont think that will come as a big surprise to many.

My interpretation is G.mgfast is just about extending the bandwidth to those lines which are short enough to take advantage.. and more efficient error correction to reduce overheads - see the mention of LDPC. Noted that its designed for twisted pair and coax - real benefits at <50m.

Kind of reminds me of what ADSL2+ did for ADSL1:  ie ADSL2 uses better coding algorithms, whilst ADSL2+ increases the bandwidth.
Its all about [modulation] technology rather than anything physical... and would need g.fast/FTTdp to be rolled out first.
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Chrysalis

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Re: ADTRAN and BT Reasearch G.mgfast – 10Gbps Broadband Down Copper Lines
« Reply #4 on: August 26, 2017, 10:37:05 PM »

I did think a short time ago that BT might not get away with advertising up to 330 for g.fast.  g.fast seems similar to adsl2+ in that almost noone will get full speed, and adsl2+ in the end had to be advertised around 16mbit.  Unless BT get really lucky with those signing up to g.fast been sub 30m to the cabinet then I think they going to have a hard time getting 10% to sync at 330mbit.    IF that turns out to be the case this may have an impact on the business case of this tech.
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WWWombat

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Re: ADTRAN and BT Reasearch G.mgfast – 10Gbps Broadband Down Copper Lines
« Reply #5 on: August 27, 2017, 04:23:47 PM »

I think G.mgfast is the technology that looks more suited to DP usage, while plain old G.Fast looks more suited to Swisscom's FTTS design (ie up to 200m) for a whole street.

I imagine copper is going to be as doomed as it ever has been: when the installation cost of fibre becomes cheap enough compared with the cost of the most viable alternative. If G.mgfast is no cheaper than FTTP, then it won't happen. As ever, it is a balance of pro vs con, with the financial having a heavy weighting.

I'm also pretty sure that the 330Mbps package will be good for marketing at "up to 300" under the current advertising rules. Getting 300Mbps is something they've been managing far beyond 30m so far.

The problem with ADSL2+ is that it was sold with an "up to" speed that matched the top of its capabilities, but which started to tail off before the copper even left the exchange building. G.Fast has an absolute maximum of around 900Mbps, which would tail off before the copper left the cabinet ... but by selling only "up to 330", they give themselves room to achieve it.

But I suspect we'll see the new regime cut in before G.Fast adverts get any traction.

@Chrys
With your talk about repurposing the fibre that is out there, I wonder if you are under a misconception about what fibre is out there.

As far as I can make out, the NGA FTTC rollout has come with a fibre spine (with lots of strands of fibres), and aggregation nodes that can tap into the spine.  But beyond this spine, the only fibre is the stuff that has gone from aggregation nodes to PCPs.

This latter stuff (it looks to me) is empty 7x or 12x blown-fibre-tubing. The tube can supply a number of PCPs; at each PCP chamber a "tube intercept joint" is inserted, that allows one tube to be extracted, and directed up into the FTTC cabinet. The fibre (as a 4-strand unit) is blown from the aggregation node to the FTTC cabinets, where 1 strand is used as a live point-to-point circuit.

With this architecture, the spine and the aggregation nodes are intended for future use - in NGA P2P and PON circuits, and in BAU leased lines. This part looks to be designed for what you want - more fibre without digging up streets.

The other part, sending fibres to the cabinets, looks to have little capacity to "repurpose" into a large-scale FTTP network.
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Chrysalis

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Re: ADTRAN and BT Reasearch G.mgfast – 10Gbps Broadband Down Copper Lines
« Reply #6 on: August 29, 2017, 01:42:52 PM »

Wombat apologies if it needs a different kind of fibre then I guess it cannot be repurposed. :)

I suppose with the last 50m or so it depends on how much value is put onto avoiding digging up gardens etc. as there is customers who hate that sort of thing and I guess the cost adds up if say on 100k installs you can activate remotely vs having to install some fibre to the socket.
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WWWombat

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Re: ADTRAN and BT Reasearch G.mgfast – 10Gbps Broadband Down Copper Lines
« Reply #7 on: August 30, 2017, 08:46:23 PM »

Wombat apologies if it needs a different kind of fibre then I guess it cannot be repurposed. :)

It really depends how much there is ... and nearer the leaves, rather than the trunk, there might not be much at all.

The architecture diagrams for FTTP suggest that, where a 2-way split is being used, or where connectorised methods are used, then some of the distribution of fibre will still be done with BFT. In that case, even empty tubing is an asset. If it isn't all used on cabinets.

I suppose with the last 50m or so it depends on how much value is put onto avoiding digging up gardens etc. as there is customers who hate that sort of thing and I guess the cost adds up if say on 100k installs you can activate remotely vs having to install some fibre to the socket.

That is, essentially, the problem of the last few metres.

The cost adds up because, while it isn't many metres per customer, it is a lot of customers. And it has to be done appointment-by-appointment. And some people don't like the idea of gardens, paths or walls being affected.

But I am aware that, while there are all these technological improvements being looked at for hybrid systems, the costs are also coming down for full fibre.
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Ignitionnet

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Re: ADTRAN and BT Reasearch G.mgfast – 10Gbps Broadband Down Copper Lines
« Reply #8 on: August 30, 2017, 11:34:22 PM »

Worth remembering that there is already WDM equipment inside some cabinets to reduce fibre count. WDM + PON = fibre-count-light backhaul goodness.

You didn't think they were playing with XGPON and NGPON purely for FTTP purposes, did you? ;)
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WWWombat

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Re: ADTRAN and BT Reasearch G.mgfast – 10Gbps Broadband Down Copper Lines
« Reply #9 on: September 02, 2017, 11:54:17 AM »

I always assumed that FTTdp solutions could well swap from a P2P fibre to a PON-based fibre for backhaul, and further assume it needs either the 10Mbps or 40Mbps variants to be viable. I've not reached a conclusion about WDM because I've not seen it mentioned anywhere, but am certainly open to the prospect. I've seen no evidence (bar your testimony) that either have actually been used anywhere in the live network. Would love BT to confirm.

When you mention WDM, are you talking about its use for multiplexing several P2P, or for multiplexing GPON, XGPON and NGPON2?

I'm also open to the prospect that copper backhaul might be used instead, and I'm still wondering what direction BT will go on power. And I still think that one is the biggest issue.
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Ignitionnet

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Re: ADTRAN and BT Reasearch G.mgfast – 10Gbps Broadband Down Copper Lines
« Reply #10 on: September 05, 2017, 12:42:55 AM »

Being used at the moment for P2P. Could be switched.

Fibre to cabinets could help with an FTTP delivery. Use 10G backhauls, PON cards in DSLAMs, upgrade any other boards that need it, ensure the software is there to support mixed mode VDSL and FTTP, happy days.
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