The role of G.Fast in New Zealand’s fibre future

Forums › New Zealand Broadband › The role of G.Fast in New Zealand’s fibre future

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Chorus

#1359807 6-Aug-2015 08:59

We don't have any plans for VDSL 30a. It's not that popular overseas so not all modems and line cards support it. Our current focus is on implementing VDSL Bandplan 998 which more efficiently uses frequencies up to 17MHz. This should provide most VDSL customers with a decent speed increase without having to replace modems.

Jase2985

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#1359812 6-Aug-2015 09:08

Chorusnz: We don't have any plans for VDSL 30a. It's not that popular overseas so not all modems and line cards support it. Our current focus is on implementing VDSL Bandplan 998 which more efficiently uses frequencies up to 17MHz. This should provide most VDSL customers with a decent speed increase without having to replace modems.

Thanks for all the info thus far, its good to see some interaction and ideas being shared about these things

Would you be able to provide more info on the 998 band plan change please?
Max up and down speeds?
what the differences will be for 8b and 17a users?
is there plans to extend the minimum range of VDSL?
I understand the rollout will be done by the end of November?
anything else worth noting?

raytaylor

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#1359862 6-Aug-2015 10:32

hio77: While g.fast wont make too much difference in NZ, the use of vectoring, on vdsl would be quite nice.

G.INP would be nice too.

I went to a presentation at chorus' office in wellington where they had an alcatel lucent rep there who told us about the vectoring feature they are introducing.

The goal of vectoring is to both increase throughput and reduce crosstalk between copper loops in the same cable or nearby cables.

At the time there were some serious limitations on how you can implement it.
- DSLAMS need to be interconnected with a vectoring control cable.
- Copper pairs need to be connected to the same network of DSLAMS in the cabinet or central office.

The problem - we have unbundling in New Zealand.
That means the fancy vectoring dslam that chorus may install cannot tell what the ZyXel dslam of ISP-X is doing, which may also be feeding some copper pairs in the same trunk cable going down a street.

So there will be some crosstalk reduction, but unbundling does limit its effectiveness

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richms

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#1359951 6-Aug-2015 12:52

So I guess ISPs being to lazy to put gear into cabinets has some benefit then ;)

Anything adsl coming from the exchange will hopefully be too weak after its 3k journey to do anything to closer vdsl in the cabinet.

Richard rich.ms

Chorusnz

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Chorus

#1359971 6-Aug-2015 13:23

Results from the 998 field trial were very positive. Average downstream speed improved by about 50% (from 35.0 to 52.4Mbps). Average upstream also improved by about 30% (from 9.6 to 12.8Mbps). The normal caveats apply i.e. there are a lot of factors that can influence VDSL speeds on an individual line, so not everyone will get the same level of improvement.

In terms of max speed, those with best of all factors (short loop length, right equipment, right premise wiring, etc.) can get up to 70Mbps or 100Mbps. The difference depends on the type of VDSL line card we have in our DSLAM. Early generation line cards, typically in urban areas, can get up to 70Mbps. Newer generation line cards, typically in rural areas, can get up to 100Mbps.

We’re currently analysing how far we can extend minimum range and hope will announce any change once field test results are analysed. One of the benefits of 998 is that it uses a very low frequency band (known as US0) for upstream which supports sync and stability on longer lines.

Once we’ve got approval from the industry via the TCF and the commerce commission, we’ll do a phased rollout across the network and update the pre-qual threshold. All by Christmas.

Jase2985

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#1360024 6-Aug-2015 14:25

Thanks heap for the info :)

Is there any way to tell if your connected to a newer line card?

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Lorenceo

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#1360027 6-Aug-2015 14:27

What will happen on lines where it causes the upload speed to drop due to less upstream bands?

networkn

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#1360034 6-Aug-2015 14:38

Jase2985: Thanks heap for the info :)

Is there any way to tell if your connected to a newer line card?

I'd also love to know the answer to this. Can I petition, beg, borrow, steal, bribe, blackmail, guilt trip or in any other manner, increase my chances of getting one of said cards or having my card upgraded if it's not one presently?

I am not quite willing to give my first born child, but almost anything else could be negotiated :)

richms

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#1360039 6-Aug-2015 14:41

Lorenceo: What will happen on lines where it causes the upload speed to drop due to less upstream bands?

I would imagine that the upstream speed would drop because of fewer upstream bands and that would be the best effort service that you end up getting.

Richard rich.ms

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#1360041 6-Aug-2015 14:45

richms:
Lorenceo: What will happen on lines where it causes the upload speed to drop due to less upstream bands?

I would imagine that the upstream speed would drop because of fewer upstream bands and that would be the best effort service that you end up getting.

sacrifice a tiny bit up upstream for a lot more downstream.

how much drop are you talking about?

Lorenceo

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#1360044 6-Aug-2015 14:49

Not keen on losing upload speed for extra download. The whole reason I got VDSL was for more upload. UFB not available here in the near future. Central Auckland suburb. Line comes in from ETP, through CAT5E and into modem. Nothing else connected to the line.

Why not enable US0 and lower the SNR on 997? There are other features VDSL can do to improve speeds as well which could be implemented such as G.INP. Any form of error correction available which does not increase latency I'm in favour of having enabled to help with poor lines.
With the band allocation it'd also be good if as much as possible can be moved out to the higher bands on short lines so there's less lower band crosstalk on the longer ones.

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Lorenceo

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#1360045 6-Aug-2015 14:54

Jase2985:
sacrifice a tiny bit up upstream for a lot more downstream.

how much drop are you talking about?

Line currently synced at 22.5/5.5Mbps on a weird DLM profile somewhere between 1 and 2 (8ms/3ms, 0.5/0 INP). Syncs at 20/4.5 on a good day with DLM1. Remains to be seen what will happen when the change occurs. If it results in extra download and no upload loss, great. I'm pessimistic over this being the case however.

Jase2985

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#1360064 6-Aug-2015 15:28

Lorenceo: Not keen on losing upload speed for extra download. The whole reason I got VDSL was for more upload. UFB not available here in the near future. Central Auckland suburb. Line comes in from ETP, through CAT5E and into modem. Nothing else connected to the line.

Why not enable US0 and lower the SNR on 997? There are other features VDSL can do to improve speeds as well which could be implemented such as G.INP. Any form of error correction available which does not increase latency I'm in favour of having enabled to help with poor lines.
With the band allocation it'd also be good if as much as possible can be moved out to the higher bands on short lines so there's less lower band crosstalk on the longer ones.

The world has adopted 998, and 997 will soon be an orphan and there wont be equipment made for it hence the need for change

From what i have seen the decrease in upload has been in the order of about .5mbps for a gain of 10-20mbps on the upload. so i doubt you would really notice it that much.

i would say wait and see

richms

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#1360100 6-Aug-2015 16:07

I'm more worried about how it will affect lines that have become borderline useless due to neglect of the copper like my flatmates line that only gets 5 meg up now and down that fluctuates depending on weather.

Already got him house hunting but if it crap out anymore... who knows.

Richard rich.ms

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#1360113 6-Aug-2015 16:16

Jase2985:
The world has adopted 998, and 997 will soon be an orphan and there wont be equipment made for it hence the need for change

From what i have seen the decrease in upload has been in the order of about .5mbps for a gain of 10-20mbps on the upload. so i doubt you would really notice it that much.

i would say wait and see

I've been doing a bit of reading on what this change will do to upload speeds on medium-long lines. Keep in mind that the change not only reduces US1 bandwidth by around half, it also moves it to a higher frequency (which suffers more due to attenuation). From looking at similar lines to mine from overseas, I'm expecting my upload is going to drop by around half. It also doesn't help that the lines I've compared it to have 6db SNR, so it could end up being even worse.

Happy to be proven wrong, but to me it doesn't look good for those who value upload speed on medium-long lines.

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