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Standard User WWWombat
(knowledge is power) Wed 08-Feb-17 01:01:46
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Re: Openreach to rollout 3dB target SNRm for FTTC next year


[re: MHC] [link to this post]
 
I concur with that, with an extra proviso...

The transmitter has to stay within the bounds of "total aggregate power" as well as within the bounds of the PSD mask for each individual tone.

That tends to mean that, where the modem is using a lot of tones, then some of the tones will transmit at a lower power than the PSD mask allows for.

So...

If the 3dB trial allows more tones to be used, that might cause a reduction in power of some/many/all of the other tones. There would be extra crosstalk caused by the extra tones, but there would be less crosstalk caused by the reduction in power on some of the other tones.

In theory, anyway. It depends how many lines hit the maximum aggregate power limit.
Standard User MHC
(sensei) Wed 08-Feb-17 02:06:49
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Re: Openreach to rollout 3dB target SNRm for FTTC next year


[re: WWWombat] [link to this post]
 
I forgot that one ...

And there are probably more variables too!

Think abut this ... Margin limit drops to 3dB, so modems agree that some previously unused tones can now support 1 or 2 bits, as they are allocated the modem realised that the total power exceeds the maximum permissible and so has to reduce power marginally on all tones. That then means the tones supporting just one bit become unviable or too close to the Margin limit and are dropped. Total power is then under the max permissible so it increase the power across all tones. Then, as the limit is 3dB is brings extra tones into play ... total power goes outside and round again .... Yes, the algorithms will probably stop that happening however it has happened of systems before.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit
Standard User RobertoS
(elder) Wed 08-Feb-17 09:47:58
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Re: Openreach to rollout 3dB target SNRm for FTTC next year


[re: MHC] [link to this post]
 
In which case the two modems would never agree a sync, so the "probably" must read "certainly".

Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
My broadband basic info/help site - www.robertos.me.uk. Domains, site and mail hosting - Tsohost.
Connection - AAISP Home::1 80/20. Sync 54999/14466Kbps @ 600m. BQMs - IPv4 & IPv6


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Standard User Icaras
(experienced) Wed 08-Feb-17 09:55:07
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Re: Openreach to rollout 3dB target SNRm for FTTC next year


[re: MrSaffron] [link to this post]
 
In reply to a post by MrSaffron:
Thanks for the time digging, seems to mean we will need to be careful about what different hardware (and maybe even firmware versions) is reporting


Do you not think that at present the Home Hubs at least will work out the max attainable based on 6dB? As that's the default on the Openreach FTTC system.
Standard User adamtemp
(experienced) Sat 01-Apr-17 08:21:31
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Re: Openreach to rollout 3dB target SNRm for FTTC next year


[re: AndyHCZ] [link to this post]
 
Looks like cab 4 on wwstal stalbridge added to trial noticed an increase today in sync and 5db snr

GLOBALNET now part of madasafish now plusnet With The same isp since 1995 ( now all part of BT) (now on a 21cn exchange wwstal 49db on adsl2 or 52.5db on adsl2+ depending on exchange sync)
Standard User lee111s
(experienced) Sat 01-Apr-17 10:49:36
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Re: Openreach to rollout 3dB target SNRm for FTTC next year


[re: adamtemp] [link to this post]
 
The trial is finished. It's now being rolled out.
Standard User djay
(committed) Tue 04-Apr-17 12:26:44
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Re: Openreach to rollout 3dB target SNRm for FTTC next year


[re: adslmax] [link to this post]
 
My line went mad about 6 weeks ago now and my sync jumped from 56-76 and 19999 upload which it always was.
I had no way to check my stats with a plusnet hub 1 so today i plugged in my hacked hg612 and this is what i got.

I am assuming the g.inp was pushed out to test the line as it's showing ennabled and also i went from 6.5db snr down to 3.1

Here are my stats

xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 27024 Kbps, Downstream rate = 77340 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 77632 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 3.3 15.1
Attn(dB): 15.3 0.0
Pwr(dBm): 14.0 6.6
VDSL2 framing
Bearer 0
MSGc: -6 26
B: 243 237
M: 1 1
T: 0 42
R: 10 16
S: 0.1001 0.3781
L: 20303 5374
D: 8 1
I: 254 127
N: 254 254
Q: 8 0
V: 0 0
RxQueue: 88 0
TxQueue: 22 0
G.INP Framing: 18 0
G.INP lookback: 22 0
RRC bits: 0 24
Bearer 1
MSGc: 186 -6
B: 0 0
M: 2 0
T: 2 0
R: 16 0
S: 5.3333 0.0000
L: 48 0
D: 3 0
I: 32 0
N: 32 0
Q: 0 0
V: 0 0
RxQueue: 0 0
TxQueue: 0 0
G.INP Framing: 0 0
G.INP lookback: 0 0
RRC bits: 0 0
Counters
Bearer 0
OHF: 0 440714
OHFErr: 0 0
RS: 69629480 1321951
RSCorr: 78 0
RSUnCorr: 0 0
Bearer 1
OHF: 108949 0
OHFErr: 0 0
RS: 1306646 0
RSCorr: 0 0
RSUnCorr: 0 0

Retransmit Counters
rtx_tx: 17711231 0
rtx_c: 8 0
rtx_uc: 0 0

G.INP Counters
LEFTRS: 0 0
minEFTR: 77619 0
errFreeBits: 2071995 0

Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 261220947 0
Data Cells: 2446303 0
Drop Cells: 0
Bit Errors: 0 0

Bearer 1
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 0 0
Data Cells: 0 0
Drop Cells: 0
Bit Errors: 0 0

ES: 0 0
SES: 0 0
UAS: 54 54
AS: 1750

Bearer 0
INP: 52.00 0.00
INPRein: 1.00 0.00
delay: 0 0
PER: 0.00 3.98
OR: 0.01 64.22
AgR: 77711.11 20063.54

Bearer 1
INP: 4.00 0.00
INPRein: 4.00 0.00
delay: 3 0
PER: 16.06 0.01
OR: 95.62 0.01
AgR: 95.62 0.01

Bitswap: 365/365 0/0

Total time = 30 min 4 sec
FEC: 78 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 54 54
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 4 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 15 minutes time = 15 min 0 sec
FEC: 39 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 30 min 4 sec
FEC: 78 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 54 54
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 1 day time = 0 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Since Link time = 29 min 9 sec
FEC: 78 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
#

no idea what half of that is tbh but it's a huge speed increase which is nice.

Downstream Upstream
General
rtx_tx 17711231 0
rtx_c 8 0
rtx_uc 0 0
LEFTRS 0 0
minEFTR 77619 0
errFreeBits 2071995 0
Bearer 0
RxQueue 88 0
TxQueue 22 0
G.INP Framing 18 0
G.INP Lookback 22 0
RRC Bits 0 24
Interleave depth 8 1
INP 52.00 0.00
INPRein 1.00 0.00
Delay 0 0
Bearer 1
Interleave depth 3 0
INP 4.00 0.00
INPRein 4.00 0.00
Delay 3 0
Standard User Icaras
(experienced) Tue 04-Apr-17 15:20:17
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Re: Openreach to rollout 3dB target SNRm for FTTC next year


[re: PhilipD] [link to this post]
 
In reply to a post by PhilipD:
Hi

As posted in ISPreview, the 3db profile will not be rolled out on ECI cabinets.

A question to those more knowledgeabl on such things, does a line with a reduced margin which sync's higher contribute more cross talk? Or is the frequency usage and power the same, and all that is changed are the amount of bits in each tone?

Regards

Phil


And yet, internally in comms to engineers Openreach haven't made a distinction between cabinet vendors. They've just said it will be rolling out nationally on a rolling basis.

I'm not saying what ISP Review are saying are wrong, but maybe an ECI solution is coming very shortly so there was no need to inform engineers it's Huawei only.
Standard User Chrysalis
(legend) Tue 04-Apr-17 23:43:11
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Re: Openreach to rollout 3dB target SNRm for FTTC next year


[re: Icaras] [link to this post]
 
ECI is been tested during this summer on a new firmware, if and "if" its tested ok then a rollout should happen this autumn.

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Standard User troublegum
(member) Thu 06-Apr-17 15:12:45
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Re: Openreach to rollout 3dB target SNRm for FTTC next year


[re: Chrysalis] [link to this post]
 
I'm on an ECI cabinet and just had a resync an hour ago. Router is now showing the following:

SNR Margin (dB) 3.4 10.0
Attenuation (dB) 16.5 0.0
Output Power (dBm) 6.7 6.8
Attainable Rate (Kbps) 82532 25801
Rate (Kbps) 76057 20000

The downstream was previously at 67Mbps with a 6dB SNR margin.

Edited by troublegum (Thu 06-Apr-17 15:13:15)

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