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Standard User Ixel
(committed) Wed 28-Feb-18 11:05:00
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Openreach Deploy Low Level Error Correction - New FTTC Lines


[link to this post]
 
I saw on another news site today that Openreach are deploying 'low level error correction' to new FTTC lines (announced by Openreach yesterday). I assume this takes effect very soon if not already perhaps.

Openreach Briefing
Currently, all FTTC VDSL2 lines are initially provided on a line profile with their speed capped at the product rate and no error protection. This can lead to customers raising faults before DLM starts working due to excessive data errors which impact their broadband service. Following the successful proof of concept we will be applying low level error correction on all new lines.


I hope this isn't just traditional interleaving which applies a minimum of 8ms. I'm more hoping it might be 'reed solomon coding' or at the very least a few milliseconds delay with no INP applied to the downstream. If it's 'reed solomon coding' then this is already applied to the upstream on fastpath usually, 'R: 16'. Reed solomon coding can reduce the potential sync rate without necessarily adding latency (or at least minimal latency compared to traditional interleaving at 8ms or higher). The only time I've seen 'reed solomon coding' on the downstream on fastpath is when I've used a modem with a Lantiq/Infineon chipset.

I've got a new FTTC service being activated on the 6th at another house I'm moving to soon, so if it's done by then maybe I'll be one of the first to see what's changed.

Discuss?

Edited by Ixel (Wed 28-Feb-18 11:06:41)

Administrator MrSaffron
(staff) Wed 28-Feb-18 11:19:56
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Re: Openreach Deploy Low Level Error Correction - New FTTC L


[re: Ixel] [link to this post]
 
It just covers the period before the DLM has decided what to do, i.e. that period when its just collecting its initial dataset to decide what to do, so if a line is totally clean and error free within limits then returning a line to no error protection seems possible.

DLM usually makes initial decision with 48 to 72 hours

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User Ixel
(committed) Wed 28-Feb-18 11:47:50
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Re: Openreach Deploy Low Level Error Correction - New FTTC L


[re: MrSaffron] [link to this post]
 
Oh I see, nice, that's not as bad as I thought then smile. Thanks.


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Standard User RobertoS
(elder) Wed 28-Feb-18 13:31:15
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Re: Openreach Deploy Low Level Error Correction - New FTTC L


[re: Ixel] [link to this post]
 
Also at the moment if G.INP kicks in the the Bearer 0 downstream interleaving is set to depth 8, but the delay parameter is set to zero. Maybe they are going to do similar.

My broadband basic info/help site - www.robertos.me.uk. Domains, site and mail hosting - Tsohost.
Connection - AAISP Home::1 80/20. 200GB. Sync 76102/14089Kbps @ 600m. BQMs - IPv4 & IPv6
Standard User j0hn83
(committed) Wed 28-Feb-18 13:42:49
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Re: Openreach Deploy Low Level Error Correction - New FTTC L


[re: RobertoS] [link to this post]
 
They are simply doing to the downstream what they already do woth the upstream.
Fastpath with a small amount of FEC. No interleaving or delay.
Standard User RobertoS
(elder) Wed 28-Feb-18 14:19:02
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Re: Openreach Deploy Low Level Error Correction - New FTTC L


[re: j0hn83] [link to this post]
 
D: is interleaving depth.

Edit: Or do you mean that's what they are going to do on new lines?

My broadband basic info/help site - www.robertos.me.uk. Domains, site and mail hosting - Tsohost.
Connection - AAISP Home::1 80/20. 200GB. Sync 76102/14089Kbps @ 600m. BQMs - IPv4 & IPv6

Edited by RobertoS (Wed 28-Feb-18 14:19:48)

Standard User Ixel
(committed) Wed 28-Feb-18 15:21:15
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Re: Openreach Deploy Low Level Error Correction - New FTTC L


[re: RobertoS] [link to this post]
 
I suspect it's more likely 'R:' (reed solomon coding), as upstream has always had 16 on fastpath while downstream on fastpath is 0 on modems with a Broadcom chipset and 16 with an Infineon/Lantiq chipset.
Standard User j0hn83
(committed) Wed 28-Feb-18 15:25:59
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Re: Openreach Deploy Low Level Error Correction - New FTTC L


[re: RobertoS] [link to this post]
 
Yes I'm referring to new lines. They are keeping them fastpath, with a small amount of FEC (R in the stats as Ixel points out).
This is already the default on the upstream.

I'm surprised they didn't do this before now. It makes perfect sense.

Edited by j0hn83 (Wed 28-Feb-18 15:27:02)

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