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Author Topic: Variable SNRM on FTTC? (3dB)  (Read 11210 times)

William Grimsley

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Re: 3db SNRM profile incoming
« Reply #15 on: March 29, 2016, 11:56:50 AM »

I have to say, I do notice the latency and throughput difference with my lower speed now DLM has banded my line... Maybe, this new SNR Margin will reset everyone's DLM? :D
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kitz

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Re: Variable SNR on FTTC?
« Reply #16 on: March 29, 2016, 12:25:53 PM »

What happens to SNR on FTTP? Does it exist, and if so is it higher than FTTC's SNR?

I'm assuming if there is SNR on FTTP then it would be higher. So when G.fast comes out, which could be seen as a hybrid between FTTC and FTTP i.e. bringng an FTTP line closer to the persons house, would this mean all our SNR stats will go up?

I guess my question is, are BT looking at SNR as they are looking for a new standard, 6dB being the FTTC standard.

Looking at WWWombat's figures in kitz post, imagine dropping the dB on a higher sync G.fast line, how many Mbps would that be worth?

FTTP isnt xDSL, so no need to worry about SNR as it connects at the given speed.  Also no DLM :)

FTTdp still involves copper, but because its shorter the attenuation will be lower and SNR higher.   It will still use a Target SNR though, 6dB is the default for most types of rDSL, but it can be set to whatever the SP wants (ie 3dB/6dB etc)
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Chrysalis

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Re: Variable SNRM on FTTC? (3dB)
« Reply #17 on: March 29, 2016, 12:42:23 PM »

Who knows with BT's trials :shrug2:

However, they are already aware of the fact that after application of G.INP, most lines run error free....  plus they know its already in use and working on ADSL2+ lines.

This isn't brand new technology, so if the trial is successful,  I can't foresee any reason why rollout should be delayed.

Quote
Question is however will it be on only downstream on ECI and will Huawei be capable of this on both up and down?

Its simply setting a configuration parameter, both types of cabs are capable of doing it both upstream and downstream, so highly unlikely it will be cab specific.   

I'm undecided how they will apply this.  IMHO the easiest way for them would be to make it like 21CN DLM as a param. But it entirely depends on how much they want to keep the speed cap.
 
1) They could replace the speed cap with a variable target SNRm and reserve capping for lines seeing high error levels.
OR
2) They could adjust the existing cap levels to fit 3dB.    Ive observed that rate limiting seems to more or less follow 6,9,12 dB, so that also would be fairly easy for them to do.


At one time BT were paranoid about users over-riding Target SNRm - they specifically saw (& cited)  DMT-tool as bad in their eyes, because it easily allowed users to play with SNRm... which is why they currently use rate limiting rather than a variable target SNRm.  So it depends if this is still a concern to them & if it is,  then I suspect they will go with option 2.

sorry I made a new thread earlier didnt see this one.

I expect the most likely way this will be done is they will adjust the SNRM target of the open profile, but any banded profiles will remain as is.

Lines on 3db exceeding ES thresholds, its harder to predict what will happen, a SNRM bump to 6db? or change to interleaving, or both.  Banding seems to not be the first choice very often.
« Last Edit: March 29, 2016, 02:50:36 PM by Chrysalis »
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kitz

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Re: 3db SNRM profile incoming
« Reply #18 on: March 29, 2016, 12:42:53 PM »

A guy on TBB who I assume has access to the BTw reports given to SP's has revealed its not long before some users will be part of a small (trial?) rollout of 3db SNRM.

Its logical to assume this will be on hauwei cabinets since they have had not very long to collect data on ECI lines.

Merged the two topics.   As stated last night, I cant see the cabinet type making any difference.

If I had to guess at anything, then I'd place a bet they had been considering this for a while..  but didnt want to roll it out to DLM until they were more certain about g.inp applied across the whole network.

However, they are already aware of the fact that after application of G.INP, most lines run error free....  plus they know its already in use and working on ADSL2+ lines.
This isn't brand new technology, so if the trial is successful,  I can't foresee any reason why rollout should be delayed.

Its simply setting a configuration parameter, both types of cabs are capable of doing it both upstream and downstream, so highly unlikely it will be cab specific.

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Oops our posts crossed.
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Chrysalis

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Re: Variable SNRM on FTTC? (3dB)
« Reply #19 on: March 29, 2016, 12:45:14 PM »

Cabinet type on a technical level shouldnt make a difference but I think they will want to be sure first that ECI cabinets are providing consistent drops of ES as are huawei, openreach generally are not aggressive in rollouts.

Then again when I made this comment on the TBB forum the guy's reply indicates I am wrong.
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kitz

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Re: Variable SNRM on FTTC? (3dB)
« Reply #20 on: March 29, 2016, 01:08:02 PM »

Based on the last convo I had with Ian Lawrence, he seemed pretty confident that G.INP mk2 would work fine on the ECI's.   Obviously I dont know for sure, but from what he said the delay was not down to the ECI cabs themselves or EU equipment.. but stability of Openreach Field Test equipment with the ECI DSLAMs.

They seem to start pretty slow with the roll out (possibly indicating they added say 100 cabs as a test and wanted to see how they performed).  For the past week or so, things have been moving much faster.

Pure speculation on my part- but it seems likely BT are now happy with the new firmware for their field test equipment...  they were confident g.inp would work fine with the ECI cabs but as a precaution added 'x' amount of cabs and monitored for 2 weeks..  then started rolling across the board.

I should think that so far they will be able to see that G.INP is a success on the ECI cabs, so can now progress to a lower SNRM across their whole estate. 
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ejs

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Re: Variable SNRM on FTTC? (3dB)
« Reply #21 on: March 29, 2016, 05:14:03 PM »

Now they just need some new firmwares for the HH5A and ECI modems so that they can do G.INP in both directions. ::)
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kitz

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Re: Variable SNRM on FTTC? (3dB)
« Reply #22 on: March 29, 2016, 06:17:27 PM »

 :-X
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S.Stephenson

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Re: Variable SNRM on FTTC? (3dB)
« Reply #23 on: March 29, 2016, 07:13:37 PM »

I made a mock up graph on what I think 3dB may look like, based on WWWombat's rule.

« Last Edit: March 29, 2016, 10:41:12 PM by S.Stephenson »
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kitz

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Re: Variable SNRM on FTTC? (3dB)
« Reply #24 on: March 30, 2016, 12:44:21 AM »

I made a mock up graph on what I think 3dB may look like, based on WWWombat's rule.

It would certainly be good if they do this :)

This weekend one of my friends said to me "I got a speed increase a couple of days ago - any idea why this is?"   
Now he's on Infinity (HH5A) so no definite proof it was G.INP, but he noticed the difference going from what used to be 53/54Mbps up to 58Mbps.
Speed bumps make people happy.
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daleski75

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Re: Variable SNRM on FTTC? (3dB)
« Reply #25 on: March 30, 2016, 08:05:12 AM »

And unlike Virgin Media they are not followed by a price increase lol

On a serious note if the snrm drops to 3db across the board could BT lift the cap so people who can get higher than 80mbit where the line allows it are able to do so or will they going by WWWombat's graph simply allow more people to obtain higher speeds at longer distances away from the cabinet?

I guess the best case would be both so people get both the higher speeds of up to 80 and others who's line supports it get 80+.
« Last Edit: March 30, 2016, 08:09:22 AM by daleski75 »
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S.Stephenson

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Re: Variable SNRM on FTTC? (3dB)
« Reply #26 on: March 30, 2016, 08:55:31 AM »

Considering BT were on about not changing the cap for a vectoring rollout I don't think they will.
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Chrysalis

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Re: Variable SNRM on FTTC? (3dB)
« Reply #27 on: March 30, 2016, 09:35:37 AM »

They wont change the cap with this, this will be to just improve the speeds for those who sync below the cap.

Not to mention 80mbit is enough for what 99% of everything out there.
A game changer would be something like 4k streaming with no compression or something along those lines.
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WWWombat

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Re: Variable SNRM on FTTC? (3dB)
« Reply #28 on: March 30, 2016, 12:11:18 PM »

I don't think BT will increase the top package speed of 80/20 through this. As mentioned, they saw the benefit of vectoring as a way of making speeds more consistent rather than faster - and vectoring probably has more potential for speed gain than a variable SNRM. I should reiterate that it doesn't have to be a 3dB target. Changes of 1dB are plausible too, just resulting in less of a gain.

I'll add a note that I was first inspired to calculate the speed equivalent of 3dB when Eircom turned on vectoring, and it still looked like BT would be too. Eircom don't use DLM, and turned on both G.INP and Vectoring at the same time, but left their standard SNRM target as 9dB.

It'll be interesting to see what mechanism they use to deploy and vary the settings.
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ejs

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Re: Variable SNRM on FTTC? (3dB)
« Reply #29 on: March 30, 2016, 04:00:43 PM »

A game changer would be something like 4k streaming with no compression or something along those lines.

Uncompressed video tends to use an infeasible amount of bandwidth:
width × height × bits per pixel × frames per second
(3840 × 2160 × 24 × 24) = 4,777,574,400 or approx. 4.8 Gbps
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