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G.fast receives final approval as an ITU standard
Saturday 06 December 2014 10:48:17 by Andrew Ferguson

We saw G.fast in action at the BT labs in Martlesham Heath back in October and the ITU has now just given its final approval to the standard in the form of ITU-T G.9701 which was around the physical layer specification after previous approval of the standard to ensure that services such as FM radio are not impacted.

Our trip to the BT labs showed how VDSL2 and G.fast can co-exist in the same local loop and with Fibre to the remote node supporting both VDSL2 and G.fast users could upgrade with the switch in speeds done remotely. While all the headlines talk of Gigabit speeds, there is a slight sleight of hand as this usually means a combined download and upload speed, but downloads of 500 Mbps and uploads of 200 Mbps look to be realistic speeds for the average distance of a home from the distribution point.

Of course if going to deploy G.fast to within 50m of a dozen properties, why not install FTTH? The simple answer is money, not the price of the fibre and tubing but the hours of labour to connect each property. If you can connect all of the properties in one go with FTTH then it is cheaper, but that tends to only happen in community led schemes.

Hopefully G.fast which is clearly seen as the way forward by the BT Group will have its costs evaluated against deploying Fibre to the Home/Premises (FTTH/FTTP) and where full fibre is cheaper the sensible approach of deploying FTTH will go ahead.

Comments

Posted by Spud2003 about 1 year ago
Sean Williams, Group Director, Strategy, Policy & Portfolio, BT - stated a few days ago that FTTP for everyone would cost five times as much and take five times as long to deploy(move to 15:24:03 in the video - http://www.parliamentlive.tv/Main/Player.aspx?meetingId=16692 ).

Copper is the future as far as BT are concerned ...
Posted by andrew (Favicon staff member) about 1 year ago
While the bulk is copper based and likely to remain that way as with the BDUK projects we are seeing more FTTP every week and if FTTrN with VDSL2 and/or G.fast is deployed we expect to see some more FTTH too.
Posted by TheEulerID about 1 year ago
This is the BSG's report on the costs of deployment (still the most credible report out there). It states a 5x higher cost for GPON FTTH vs VDSL/FTTC.

http://www.broadbanduk.org/wp-content/uploads/2012/08/http___www-broadbanduk6.pdf

nb. my estimate is that a national FTTH solution could be achieved at a wholesale incremental cost of around £3 per line recovered over 30-35 years.
Posted by TheEulerID about 1 year ago
That's £3 per month of course (and involves some optimistic estimates of financing costs and how - eventually - copper maintenance costs come down and the investment valuation of that gradually falls out). Note that any such project would probably take 10+ years at the shortest, and thee would be parallel running in any one area for several years (as in Jersey).
Posted by WWWombat about 1 year ago
@Euler
How do you plan protect a company that has invested, so that it actually has the 30-35 years in order to recover that money?

Part of the same video that @Spud points to shows BT couldn't go faster, even if you paid them more: constrained by the manpower they can employ. Apply that to a full FTTP rollout, and you might find it takes more like 20-30 years.
Posted by WWWombat about 1 year ago
That manpower limitation would probably mean that an FTTdp rollout would go on for a long time too; FTTC has taken 5 years so far...
Posted by TheEulerID about 1 year ago
@WWWombat

That problem of how to give investors confidence has been troubling regulators and economists for years. Plenty of papers on the subject. It would probably require protection against "cherry pickers". Australia did that for the NBN.

As for timescales, then I think 15 years is more viable than 10 or it will get hugely expensive.
Posted by TheEulerID about 1 year ago
It appears "cherry pickers" are still an issue in Australia.

http://www.theaustralian.com.au/business/in-depth/nbn-services-will-be-compromised-if-it-has-supplier-competition/story-e6frgaif-1226972890014?nk=77853cff992bd5b4dd59068371fed41d

The other issue in the UK is, of course, the large cable network. That's in a position to undercut any fibre roll-out if the latter was allowed to charge a premium.

Once the market fragments, the national FTTP business case crumbles.
Posted by kijoma about 1 year ago
hmm there is lesser known rule in engineering called TANSTAAFL* , it always applies.

Ratified based on non interference to FM broadcast at around 100 MHz ? Boy this is going to give the HF radio amateurs and shortwave listeners an even greater reason to rant than the powerline / homeplug fiasco!.

I'd be interested to see how it deals with crosstalk and strong interferers (like all those broadcast services from 1 to 100 MHz!) in the real world.

For the last 50 metres why not just pull through some cat6. , like a cable network works :D

*Their ain't not such thing as a free lunch)
bill
Posted by TheEulerID about 1 year ago
Is it really such an issue? DSL transmission powers are very low, and it's over twisted pair which greatly limits how much power is radiated. OK, phone cable isn't as good as CAT6, but just how good does it need to limit radiation?

Note, there may be some older drop wires which aren't TP not to mention household extensions, but they would not be satisfactory for g.fast anyway.

"pulling" through is not on. It's not that simple, and you might as well use fibre.

Posted by andrew (Favicon staff member) about 1 year ago
Cable networks are coax not CAT6, with a twisted pair alongside for the telephone.
Posted by TheEulerID about 1 year ago
I've just been doing some trawling around the Internet for examples of actual interference from VDSL as there were similar worries about that as it overlaps with some RF bands. I can't find very much at all.

It also appears that g.fast has a max power spectral density much lower than does VDSL2

nb. powerline is not a great comparator as mains cabling is, to put it mildly, rather poorly balanced and it has to work in a very noise environment.
Posted by TheEulerID about 1 year ago
Oh, and I forgot to mention it supports "notching" of course.
Posted by timmay about 1 year ago
I still hope that BT will have some common sense... for example all internal wiring in the block of flats I live in is Ethernet so they should just do FTTB and offer Gbit Ethernet to each flat. If BT doesn't then eventually Hyperoptic will :-D
Posted by Dixinormous about 1 year ago
The UK cable network is very unusual in having a twisted pair alongside. In most places the voice service is delivered on the coax as well.

That'll be happening in the UK in the not too distant future too.
Posted by uniquename about 1 year ago
What would be the point of VM replacing all its twisted pair phone connections with coax?
Posted by TheEulerID about 1 year ago
@uniquename

Simplifying the network topology maybe? However, here would be a problem as, unless the modem had a UPS, it would fail the fixed line regulatory requirement for emergency service access during power cuts.

VM could just go VOIP, which is not covered by the fixed line rule, but might displease current customers. I think it's unlikely at the moment.
Posted by Dixinormous about 1 year ago
Not having to maintain a legacy TDMA telephony network would save a lot of money and allow VM to retire equipment both streetside and in their hubsites.

EMTAs with integrated battery backups are certainly around and deployed widely.
Posted by AndyCZ about 1 year ago
There is very little cost difference between rolling out native FTTP and FTTdp.

Posted by adslmax about 1 year ago
G.fast and vectoring in 2015 by BTO (no chance!) fat chance! More likely have to wait until 2020!
Posted by godsell4 about 1 year ago
quote: "DSL transmission powers are very low, and it's over twisted pair which greatly limits how much power is radiated. OK, phone cable isn't as good as CAT6, but just how good does it need to limit radiation? "

And it maybe still that to replace the wire from the DP with CAT6 maybe the cheaper option.
Posted by godsell4 about 1 year ago
@AndyCZ there is if FTTP requires a lot of digging to happen. Or if there is no digging, it may require the installer to lift eaves, get under floorboards, etc, to be able to replace the wire with fibre.

FTTdp does require as much of this manual work and complication, BTO has to figure out a standard way of getting a pole mounted DSLAM onto a pole, power connected, then the phone lines connected from each house/building. Using the existing twisted pairs from the DP.
Posted by Blackmamba about 1 year ago
Hi Broadband Watchers.
Please remember there are many DP,s or foot way boxes with black fibre running close so the provision costs will be very low so BT will go cherry picking then move on to other locations providing new fibre via Underground or Overhead. Then who is the owner of the ports.
Posted by andrew (Favicon staff member) about 1 year ago
@Blackmamba - dark fibre I presume you mean. If fibre was that pervasive why is so many km's being installed as part of the FTTC roll-out.

Posted by Blackmamba about 1 year ago
Hi Andrews Staff
The dark fibre on these locations have been run passed to service the new FTTC on many locations. They are using the same principle BT used back in the 1970 when BT was short of E sides eg (24 D sides customers on 4 E sides)
Posted by Blackmamba about 1 year ago
Hi Andrews Staff
The power to the unit above was over the four E Sides where the above would be powered from the Customer back over the drop wire.
Posted by WWWombat about 1 year ago
@BM
Having dark fibre that is part of the spine (the only kind of NGA fibre laid so far) run past a DP is about as useful as having a pressurised E-side cable run past a DP. You aren't going to get a breakout in either case.

To put a breakout in the spine makes an AGN. Read the instructions for that, and you see that it needs 8m of cable spare in a JUF4, more for larger footway boxes.

If they've left 8m+ of spare cable in every footway box with a DP, you'll be right...
Posted by andrew (Favicon staff member) about 1 year ago
@Blackmamba As ever I am confused. The power to what unit. The trial G.FAST unit in the BT labs was powered over the mains, or do you know of some super secret G.FAST deployment in the UK?
Posted by deadman1984 about 1 year ago
i dont mind if its fttdp or what as long as it improves my speeds and makes them better not worse.
Posted by AndyCZ about 1 year ago
BT did briefly deploy G.fast for a trial with Huawei in a residential area, which I assume was next to Adastral Park - http://www.huawei.com/en/solutions/broader-smarter/hw-001624-singlefan.htm
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