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Re: £5 for 5GB - Split for discussion on potential speed advantages of ADSL2+

wurzel
Grafter
Posts: 35
Registered: 13-01-2010

Re: £5 for 5GB - Split for discussion on potential speed advantages of ADSL2+

But if I am on Market 1 Exchange and getting 0.75MB will there be any advantage in changing to Extra
other than the 60GB ?
[Moderator's note by Jim (Oldjim)  title changed to suit split off topic ]
23 REPLIES
xpcomputers
Grafter
Posts: 460
Registered: 13-04-2007

Re: £5 for 5GB

If you follow this link, you can see a table outlining where EXTRA fits in the overall scheme of things.
There are two ways that EXTRA might give you more speed over and above VALUE.
1)  You might get a faster connection speed to the exchange.
This is the "up to 8MB" bit you often see quoted in adverts (also called ADSL 1), which is the maximum for VALUE, whereas EXTRA allows for you to use the newer "up to 20Mb/s" technology (also called ADSL 2). However, whether you are able to use it or are stuck with up to 8Mb/s depends on whether your exchange allows for the faster speeds.
Also before you get too excited, most people won't see 2.5x faster connections on the newer technology, and will only see much more modest  improvements. If your exchange isn't enabled for ADSL2, then you will still be on ADSL 1 even on EXTRA anyway. Your distance from the exchange and the quality of the line will still have a lot of influence on the final speed you will get, with the average user if they currently get 4Mb/s on ADSL1 upping to ADSL2 might only raise you to 5Mb/s...  which is still worth having though! This is summed up the "Speed" column of the table in the link above, with VALUE being ADSL 1 only, whereas all other packages allow ADSL 1 or ADSL 2 as your exchange allows.
A slightly flawed but possibly helpful analogy: If you think about the speed limit for cars on the motorway, changing from ADSL 1 to ADSL2 is a bit like changing the top speed for cars from 70mph to 80mph (or faster). However this change won't affect trucks & tractors which have even lower speed limits enforced... but these are dealt with in the second improvement below.

2) The traffic profiles are better for some types of internet traffic on EXTRA compared with VALUE.
Traffic Profiles are like speed restrictions for various types of vehicles on roads. So like on roads maybe cars can do 70mph, but trucks might only be able to do 60mph, and tractors 15mph etc. In a similar way, better traffic profiles would see some types of traffic get faster speed limits than they do on VALUE. Cars in this analogy would be like visiting normal websites and downloading emails, and they are always at top speed on any Plusnet Package (VALUE, EXTRA, PREMIUM, or PRO) - so makes no difference for them which package you have. It is the likes of trucks and tractors who's speed limit gets raised, which might be downloading files, FTP, or peer to peer traffic types. If you only visit simple websites, then VALUE and EXTRA will be a similar speed to you. If you do other things, they might be allowed to run faster on the more expensive packages. In the table I linked above, I have crudely simplified this as a "Quality" rating of "Good" for VALUE.... "Better" for EXTRA (and the outgoing PREMIUM)... and "Best" for PRO.
The analogies are a bit crude, but might help you understand more.

Mike
Community Veteran
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Re: £5 for 5GB

If you are like me - a long way from the exchange (53dB attenuation) and don't use P2P or Usenet or on-line gaming then the only significant advantage is a slight speed increase in external FTP speeds at peak periods. This is the best site to compare (assume Extra is the same as Premier) http://www.kitz.co.uk/isp/plusnet_shaping.htm.
The only other advantage is a potential increase in upload speed (emailing large files is quicker)
If you want to check the sort of speeds you could get on ADSL2+ put your attenuation in here http://www.kitz.co.uk/adsl/max_speed_calc.php
xpcomputers
Grafter
Posts: 460
Registered: 13-04-2007

Re: £5 for 5GB

What speed you'll see from moving to ADSL2 will vary from line to line, but the best improvements often come on the slowest and fastest lines.
So at a guess,
0.75Mb/s on ADSL 1, might get you a 20% - 100% increase on ADSL 2
4Mb/s on ADSL 1, might only get you a 10% - 50% increase on ADSL 2
8Mb/s on ADSL 1, might get you a 200% - 250% increase on ADSL 2

Warning, it seems these figures I guessed at could be very inaccurate... so ignore the above guesses and only use Kitz's tool (below) to get a feel for likely speed!
but you'd be better to go to Kitz's website for her speed estimator tool.... which might give you a more accurate idea... but whilst more accurate than my guesses, is still only an approximation! (Occssionally people can get a slower connection on ADSL2 than on ADSL1, but I believe that is rare).
Mike
ps  ... SNAP! ...Jim is clearly a faster at typing than me!
Community Veteran
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Re: £5 for 5GB

Mike,
Can you provide some references for those speed increases as all the graphs I have seen show negligible speed increases at very high attenuations
pierre_pierre
Grafter
Posts: 19,757
Registered: 30-07-2007

Re: £5 for 5GB

well my current synch is 8128, the estimates all say 10M, thats not much
xpcomputers
Grafter
Posts: 460
Registered: 13-04-2007

Re: £5 for 5GB

Quote from: Oldjim

Can you provide some references for those speed increases as all the graphs I have seen show negligible speed increases at very high attenuations

No unfortunately not.  I'd take my suggestions with a HUGE pinch of salt. I have no graphs or even real experience (still on ADSL 1 here right this moment!). It is a hunch I've picked based on things I've read in various places across the net, but nowhere particular I could quote.
I think it depends a lot on the reason for the slow speed. As I understand it, ADSL2+ uses a much wider frequency spectrum of signals which travel long distances less well. So that would suggest that slowest lines get the slowest speed increases, whilst the shortest lines get the full gain... with the middling distance getting a middling speed increase.
However, the real world is never like the labs and the text books precisely....
Here I am making it up as I go along... possibly the slowest lines are more likely to have local interference that is causing the the problem? And the extended frequency spectrum allows more through? I think if it is a very long line that causes the speed to be slow, I think the reality is you'd get only a small or no gain from the extra ADSL2+ frequencies, as almost certainly they wouldn't go the distance. Why some slow lines get a better gain (if they do?) is a ultimately a mystery to me, and of course might not even be true!
I'd actually like to see some graphs of expected experience myself... so if anyone finds any, compiled solely of real world examples (not test cases), I'd love to see them.... to see if the anecdotal evidence I've heard is correct or a load of cobblers! Wink
Mike
VileReynard
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Re: £5 for 5GB

Quote from: xpcomputers
What speed you'll see from moving to ADSL2 will vary from line to line, but the best improvements often come on the slowest and fastest lines.
So at a guess,
0.75Mb/s on ADSL 1, might get you a 20% - 100% increase on ADSL 2
4Mb/s on ADSL 1, might only get you a 10% - 50% increase on ADSL 2
8Mb/s on ADSL 1, might get you a 200% - 250% increase on ADSL 2
(Occssionally people can get a slower connection on ADSL2 than on ADSL1, but I believe that is rare).

I would dispute that.
People on medium/long lines won't even get ADSL2+  - it will be ADSL2, which uses the same bandwidth as ADSL MAX.
If I was on 0.75Mbps, I'd try asking for a fixed rate 2Mbps line - worth a try!

xpcomputers
Grafter
Posts: 460
Registered: 13-04-2007

Re: £5 for 5GB

Jim &  A fox is evil,
I've put a suitable warning on my above guesses until we can be more factual about it, since I don't want to mislead anyone.
However, I've just done a search and found this graph and would be interested in what you think.
It is from Australia so the technology used (and the quality of the wiring used etc) might not be an exact match for the UK, but they do seem to suggest that the middle gets little or no improvement, whilst the top end gets the most, and the bottom end see both the connection speeds and stable line length improve. I've not seen that graph before, but it would fit with the anecdotal evidence I've read about in other places.
What is most surprising to me, is that if you follow the green curve, the middle ground (2Mb/s to 4Mb/s) potentially gets next to no gain at all, unless we are using the variation of the technology that they call "range extended" (eg the yellow curve). I'm not sure if the UK uses such technology, but things I'd read previously suggested to me that do we see something like that yellow curve in the UK (rather than the lower green curve), so maybe all our ADSL2+ is the range extended type here since it is being implemented much later than in Australia. (eg they have a table underneath compiled from a study of their ADSL2+ customers in Dec 2006 (presumably a while after it was all installed!)... and yet BT are only just rolling this out here in the UK!!! )
Don't want to take this off topic though, although it is related to answering the question... "how might Extra be faster on a given line?"
Mike
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Re: £5 for 5GB

Mike,
I did a quick search and the big problem appears to be cross talk however I noticed here http://www.iwr.co.uk/itweek/news/2085151/adsl-extend-reach that BT may have trialled it with respect to getting a basic ADSL capability on longer lines but I am not sure if that is available for ADSL2+
However according to this http://www.techreplies.com/internet-broadband-30/extended-reach-dsl-225879/ Plusnet were involved in the trials in 2003
xpcomputers
Grafter
Posts: 460
Registered: 13-04-2007

Re: £5 for 5GB

Thanks for those links.
I wonder if all of BT's ADSL2+ equipment is what the Australians would call "range extended", in that everything I've read about lowish mid-range improvements in the UK would suggest the yellow curve is more typical here than the green curve. It needn't be even called "range extended" here, it might just be that since the equipment is only just being installed in these exchanges here, that all of it supports the newer ratified standard that models the yellow curve ("range extended" just being a marketing name we don't need?).
That graph is the only one I've found so far, and it tallies with what I've read about here in the UK in real world observations, but it is hardly conclusive evidence! I'll keep my "guesses" retracted for now... and keep hunting.... but I'd be very interested to know if Plusnet have any before and after data on sync speeds on shifting to ADSL2+, compared with line attenuation, and line length.
I think we perhaps ought to hive off this discussion into a new thread (maybe with a few "choice" posts duplicate in both to keep an "answer" on speed here, but then let the technical discussion go elsewhere). I assume you can wave a magic wand to do this Jim?
Mike
(fastens seatbelt for the impending whirlwind ride!)  Cheesy
Community Veteran
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Re: £5 for 5GB - Split for discussion on potential speed advantages of ADSL2+

Split off - however I can't duplicate posts so I moved the whole discussion
xpcomputers
Grafter
Posts: 460
Registered: 13-04-2007

Re: £5 for 5GB - Split for discussion on potential speed advantages of ADSL2+

Thanks Jim,
Didn't want to derail the other thread any further... (might be worth a note & link in that thread indicating where the posts went, since I was even subscribed to that thread, but didn't get notification of where these split posts went to!)
OK, I found a different graph which suggests a curve more like you guys were expecting:
http://www.beforum.co.uk/showthread.php?t=6490
Obviously this graph is based on BE/O2's technology, which again might be more, or less different from BT's than Internode's Australian stuff. Who knows?
Strangely the particular average figures I remember reading somewhere (in more than one place I'm sure) were something like:
6+Mb/s gets good gains
4Mb/s  might get about 5Mb/s
2Mb/s to 3Mb/s might stay about the same (or get a very slight increase).
0.75Mb/s might see up to 1.5Mb/s
Although bare in mind that these are the memories in my head only, so might well be remembered wrongly... and I have no access to the source either, since I can't remember where I read them now... so the source itself might have been wrong, or statistically flawed methodology! Which added to my memory doesn't make for a very accurate guess now!!! Having said that, I am still intrigued that it loosely matched the Internode curves! Especially since I remember enough about my unknown sources I read to remember that they were based on UK data and based in real world experience which surprised the testers as deviating from the theory.., which is why the anomalies stuck in my head...
I can see I'm really going to have to wrack my brains to see if I can trace where I read this from....
Looking again at the Internode graph in detail, maybe the green curve does match my mind's figures better than the yellow.... eg no gain 2 - 3 Mb/s. It wouldn't be much of a tweak to imagine 4Mb/s yielding up to 5Mb/s in the top end of the "middle dead spot". You can even see 0.75Mb/s yielding up to double in the bottom section of green! I certainly don't picture the far right of the yellow curve as being correct though, so I take that bit back.... it gains far too much extra speed and length than I picture being true of the UK... so I revert to the green curve as more closely matching the sources I've read... but obviously they deviate quite strongly from the curves in the BEforum link which might yet be more accurate!
I might try to extract the points I've quoted above from Kitz's tool, to see what she predicts at those sorts of speeds,.. (not that that will be that scientific, but would be an interesting comparison!)
Mike
wurzel
Grafter
Posts: 35
Registered: 13-01-2010

Re: £5 for 5GB - Split for discussion on potential speed advantages of ADSL2+

Jim,
I find the above interesting,but where does it leave my original question ?
I want to know if I change from Value to Extra will my download of 0.75MB increase ?
If it is any help I am on the Kimpton Exchange in Hertfordshire and I am 5.44km away (8.69km by road)
My Down Attenuation is 63.0dB
I use about 6 GB a month.
Any help with this would be appreciated.
Superuser
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Re: £5 for 5GB - Split for discussion on potential speed advantages of ADSL2+

Kitz used quite a lot of user feedback (from all ISPs) to check and refine her figures to reflect real experience in the UK, though probably largely LLU for above 8M.
David