UFB 2+ and VDSL Vectoring

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wratterus

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#222828 30-Aug-2017 15:11

Just been looking at the press release from Chorus re the UFB2+ rollout etc, can be found here if anyone wants.

https://company.chorus.co.nz/file/80005/Presentation-30-August-2017.pdf

That's really cool news, a much higher cost per connection but that is to be expected as the density reduces. Long term I believe it is definitely a good use of money.

The VDSL Vectoring is what really interests me - I've got a few questions about it.

In the press release Chorus only mention 'rural areas'. Perhaps only cabinets in a non fibre area would be upgraded, to keep costs down and encourage people to switch to fibre where possible? That does sort of make sense.

The tech itself - do both the Ikanos and Broadcom cards being currently used support Vectoring already? Just the Broadcom maybe? Is it just a software upgrade, or does some equipment actually have to be replaced?

My (very limited) understanding of Vectoring is that it is basically like noise cancellation, but for it to work effectively, every modem on a particular cable 'bundle' would have to support Vectoring and it would need to be enabled to get any meaningful benefit. If that is the case, how do you think that will be policed?

Cheers!

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#1855316 30-Aug-2017 15:16

Chatting about this on reddit in the NZ area.
It will not be on ULL exchange areas, Only existing cabinets not in exchange areas due to ULL (Vodafone, Slingshot) so Chorus can't control their noisefloor in those areas.

Every modem must support it.
Broadcom and Ikanos cards support it IIRC.

Just noise cancelling and rearranging where the noise is! Youtube have some good videos on it.

DarkShadow

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#1855323 30-Aug-2017 15:26

wratterus:

In the press release Chorus only mention 'rural areas'. Perhaps only cabinets in a non fibre area would be upgraded, to keep costs down and encourage people to switch to fibre where possible?

It's 'rural and LFC areas', in other words, where Chorus don't have a fibre network. They wouldn't want to compete against themselves.

Sounddude

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#1855347 30-Aug-2017 16:09

Coil is correct

You can only vector if you you are the only provider putting signal into a copper bundle. Otherwise you get too much interference.

CHorus would also have to replace the VDSL line cards to do vectoring, which they would be reluctant to do in UFB areas (they are also being paid to do it in Rural areas).

hio77

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#1855350 30-Aug-2017 16:16

i understood not all linecards currently out there do support vectoring, so those definitely would be a cost to performance factor - WAK/C is happy to trail new cards chorus ;)

Vectoring was always on the cards, I'm keen to see it go live where feasible.

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raytaylor

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#1855514 30-Aug-2017 21:17

Vectoring works by reducing background noise on your line to improve the signal to noise ratio.

The better your radio signal, over the background noise, means the modems can run at a faster speed at each end.

However when many copper pairs run in a bundle down the street, cross talk occurs where a signal intended for one house, traveling down one copper pair, can be magnetically inducted into a nearby pair destined for another house. That induction (or crosstalk) contributes to the interference noise.

Vectoring counters this by actively analysing the crosstalk between the copper pairs running to different houses. As a signal is sent down the pair to House1, there will be a reverse signal sent down the pair to House2 and House3 at levels which null out the signal entering those pairs from crosstalk.

House2 and House3 will therefore have a lower noise level and a cleaner signal allowing for a boosted speed.

The problem is that the DSLAMS must talk to each other. The Alcatel Lucent ones that chorus are using have a special cable that runs between the dslams and allows the vectoring data to be passed between the dslams so they are aware of each other. However that data cant be passed to a non-Alcatel Lucent DSLAM because ZyXel or other brands are not compatible with the vectoring.

Hence why it wont be very effective if its used in exchanges that have 3rd party equipment in them - since two neighbours could use two different ISPs, one of which may have a non-vectoring DSLAM in the exchange.

One may remember back in the days of Xtra Go Large.
The launch of this plan meant that many users were no longer constrained by 20-50gb conection plans. They started using the internet more and so in many urban fringe areas, a large number of subscribers found they couldnt get a DSL signal.
If you were close to the exchange it was awesome - you could surf, use more internet, and of course you went ahead and did!
However while you were consuming more data, you were creating cross-talk noise on other pairs running in the same trunk cable down the road.
So those further out from the exchange that were just barely connected.... eg. had a sync rate of 300kbits or less, would find all this extra noise on their line, combined with the low signal due to the length of their line suddenly found their modems couldnt sync with the dslam due to the low signal to noise ratio. So where they had a slow-but-usable connection, suddenly they had nothing.
Vectoring at this time would have solved this problem, and made a considerable improvement at the same time.

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atomeara

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#1855749 31-Aug-2017 10:28

Chorus are in the process of replacing every single ISAM ADSL and VDSL line card with a new VDSL line card, that will support vectoring.
They have thousands of cards sitting in the basement of Mt Eden exchange from all over Auckland.

I am interested to see where they deploy it, the wording suggests rural and other LFC areas but not Chorus UFB areas.

Subject to the changes being passed into Law, they can withdrawal UCLL from 2020.

wratterus

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#1855786 31-Aug-2017 10:55

hio77:

Vectoring was always on the cards...

Pardon the pun haha

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hio77

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#1855957 31-Aug-2017 13:55

atomeara:

Chorus are in the process of replacing every single ISAM ADSL and VDSL line card with a new VDSL line card, that will support vectoring.
They have thousands of cards sitting in the basement of Mt Eden exchange from all over Auckland.

I am interested to see where they deploy it, the wording suggests rural and other LFC areas but not Chorus UFB areas.

Subject to the changes being passed into Law, they can withdrawal UCLL from 2020.

in the basement? Pretty sure my cabinet would be an far better place to relocate them ;)

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atomeara

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#1856145 31-Aug-2017 20:49

* That was all the old cards in the basement

hio77

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#1856164 31-Aug-2017 21:35

atomeara:

* That was all the old cards in the basement

ah well then, those can burn in a fire...

resell to NBN co. ;)

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hio77

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#1856196 1-Sep-2017 00:55

So how many dslams is 20M$ of linecards... hmm...

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Coil

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#1856228 1-Sep-2017 07:09

hio77:

So how many dslams is 20M$ of linecards... hmm...

If you could tell me how much a D Slam could Slam if a D Slam could Slam D you will know.

atomeara

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#1856351 1-Sep-2017 09:19

I don't think the 20 million is part of the current line card replacement project, as that project is well underway under the current budget.

I am hoping they use it to replace a few more BUBA cabinets but I really don't know.

hio77

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#1856917 1-Sep-2017 19:40

https://www.edpnet.be/en/support/installation-and-usage/internet/what-is-vectoring-technology.html

On the hardware level, VDSL2 line can only be vectored if two following requirements are fulfilled: modem installed on it should be vector-compliant and, at the same time, each modem installed on every other line of the same bundle is vector-compliant or at least vector-friendly. Otherwise, a modem, which is not at least vector-friendly, is installed on any other VDSL2 line, will interfere with the calculation of the cross-talk between the lines. Thus, the cross-talk from some line will remain uncancelled, resulting in an unpredictable negative impact on all other lines of the bundle.

In order to prevent it, all modems that are not at least vector-friendly will synchronize on a fallback profile (7000/512 Kb/s) that will not create more cross-talk than the one coming from ADSL2+ lines and will not disturb the continuous cross-talk estimation. On the contrary, a vector-friendly VDSL2 CPE does not disturb any other lines in the cable, but will not allow to benefit from the advantage of vectoring, being a higher speed rates.

I really hope Chorus pull through with something like this.

as a RSP rep, I'm not keen to replace what could be a large quantity of modems (I'm not 100% on Vectoring compliance of all spark modems)

However as a customer, absolutely i agree If you are causing pain to other customer's connections you should have to resolve that.

7/.5 may be exteme but i like it.

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Jase2985

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#1856926 1-Sep-2017 20:06

so i take it it needs to support the ITU-T G.993.5 standard?

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