Is this a sign of things to come?

So I have been with BT Infinity 2 for approximately 1 month now and it seems my sync speeds are steadily dropping on a weekly basis. My day 1 stats were the following:

http://i491.photobucket.com/albums/rr278/icemansin/J...

But as of now my sync speed have dropped. See below:

http://i491.photobucket.com/albums/rr278/icemansin/J...

So do I just have to accept the fact that my sync speeds will continue to drop as more as more lines are connected in the FTTC and as a result there is likely to be more crosstalk? Or is there anything I can do? Is there a potential problem with my line? I doubt I can request someone to look into this, unless I can provide concrete proof of a problem. Does anyone have any ideas?

Edited by Icemansin (Wed 11-Jul-12 00:11:37)

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The sync has fallen by 474kbps?

It looks to me from the attenuation figures that you are on the borderline for the full 80Mbps. I accept the "Max" figures have dropped, but those vary minute by minute. What time of day were the two sets of graph taken? Daytime will probably have higher valus than night-time.

In reply to a post by Icemansin:

So do I just have to accept the fact that my sync speeds will continue to drop as more as more lines are connected in the FTTC and as a result there is likely to be more crosstalk?

Probably. Over the nine months that I've been on an 80/20 connection my profile has dropped from ~70Mbps to ~62Mbps. I'm about 450 metres from the cabinet.

Or is there anything I can do?

Move to a house nearer the cabinet

The current sync speed has fallen by a small amount, but I was referring to the max sync speeds. I'm also assuming that when the modem does eventually resync, it will match and not exceed the current maximum sync speeds, so I would then be connecting at 70Mbps (which is still good).

Those graphs have been taken late in the evening.

That doesn't sound too good, well I've only been on BT Infinity 2 for a month as FTTC has only just become available in my area. I'm just concerned that the maximum sync speeds have dropped by 16Mbps in just a month, which will have a negative impact on my current sync speeds.

So over time my sync speeds could actually half...

In reply to a post by Icemansin:

I'm just concerned that the maximum sync speeds have dropped by 16Mbps in just a month, which will have a negative impact on my current sync speeds.

Yes, but if, say, the max had dropped from 100Mbps to 84Mbps you'd probably never notice. It's just a matter of how far you are from the cabinet and how many users are connected, neither of which you have any real control over.

So over time my sync speeds could actually half...

That's probably a rather pessimistic outlook... as your max sync drops it effectively becomes less sensitive to increasing numbers of users because it's not using so many high frequency slots. So the first (eg) 20 users will have much more effect than the next 20 (I think!).

When (if) the cabinet gets filled to capacity that will be the slowest you'll get. I've no idea what fraction that will be of the "clean" value, but I doubt it will be as low as 50%. I hope not anyway, for my own sake- I can't afford FTTP even if it were available!

In reply to a post by Icemansin:

That doesn't sound too good, well I've only been on BT Infinity 2 for a month as FTTC has only just become available in my area. I'm just concerned that the maximum sync speeds have dropped by 16Mbps in just a month, which will have a negative impact on my current sync speeds.

So over time my sync speeds could actually half...

My max sync speed has dropped from over 84Mbps to around 71Mbps since I was connected 3 weeks ago but seems to have stabilised now. It's probabaly DLM doing it's thing.

In reply to a post by billford:

Probably. Over the nine months that I've been on an 80/20 connection my profile has dropped from ~70Mbps to ~62Mbps. I'm about 450 metres from the cabinet.

Exactly the same for me at exactly the same distance, which is mildly reassuring!

Edited by kasg (Wed 11-Jul-12 09:06:01)

And presumably the cross-talk will be between pairs in the same bundle?

There would normally be more than one bundle of pairs coming out of the PCP going in different directions.

One of the factors as well as distance from the CAB will be the number of houses in the street - if it is a short close off a main street the number of pairs coming in can be quite small.

I live in a close with 20 houses and no scope to feed other premises from this. The PCP is just outside the entrance and the coverage radiates out from this. Cable run will be less than 100 metres, splits into two soon after the entrance so I would hope that only 10 pairs or so will serve our part of the street - been surveying BT manholes!

In reply to a post by billford:

When (if) the cabinet gets filled to capacity that will be the slowest you'll get. I've no idea what fraction that will be of the "clean" value, but I doubt it will be as low as 50%. I hope not anyway, for my own sake- I can't afford FTTP even if it were available!

How much will FTTP on demand cost?

Is vectoring technology the likely solution to these problems then? (crosstalk) If so, does anyone know if it is something that is planned to be deployed any time soon?

In reply to a post by Icemansin:

How much will FTTP on demand cost?

I'd guess that the monthly costs will probably be broadly comparable to FTTC, adding a bit for the higher speeds, but the installation costs are likely to be several hundred pounds at least, probably nearer a grand.

Vectoring is designed to help negate the crosstalk, and BT is planning it, but not for a couple of years.

There is a good reason the speeds for distance versus connection speed on http://www.thinkbroadband.com/guide/fibre-broadband.... are so pessimistic, this takes into account worst case cross talk on VDSL2

In reply to a post by MrSaffron:

Vectoring is designed to help negate the crosstalk, and BT is planning it, but not for a couple of years.

There is a good reason the speeds for distance versus connection speed on http://www.thinkbroadband.com/guide/fibre-broadband.... are so pessimistic, this takes into account worst case cross talk on VDSL2

There could be a problem with rolling out Vectoring. The next stage will be going up to Profile30 and that will require, potentially, almost twice the processor power for the software modem on each line. Add in Vectoring which needs to monitor cross talk and then generate an appropriate cancellation signal across the whole band - that will require further processor capability.

Are the current lines cards capable of the increase in CPU load? Potentially not.

It is wait and see, five year life span probably for the line card

If UK is to meet EU 2020 targets and still rely on FTTC, then profile 30 and vectoring will both be needed.