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Sky Broadband and BT Upgrade UK Internet Platforms to Boost Performance

Friday, October 4th, 2013 (8:10 am) - Score 4,466
network connections

Customers of Sky Broadband’s dominant fully unbundled (MPF LLU) network should now be benefitting from two subtle ADSL2+ performance improvements after the ISP confirmed that it had recently added G.INP and Nitro technology to help “boost line stability and speeds“. BT are also testing G.INP but for superfast FTTC lines.

The chances are good that most people won’t be familiar with G.INP or Nitro and indeed, in the grander scheme of things, you might struggle to notice what improvements they bring. The same could also be said about all the other little improvements that have quietly been introduced to help make both ADSL2+ (up to 20-24Mbps) and the latest VDSL2 / FTTC (up to 80Mbps) connections better over the past few years.

Never the less it’s sometimes interesting to point these things out, especially after the changes quietly cropped up on BE’s Help Page. Similarly BE Broadband’s recent “Talk to Sky” event confirmed that both of these have only “just rolled out” to Sky’s platform. So what do they do and why should you care? We’ll start with the better known G.INP.

Sky’s MPF Broadband Upgrades

* G.INP (Part of the ITU’s G.998.4)

This is designed to dynamically reduce a connections Bit Error Rate so as to hopefully make some lines more stable for things like video streaming and IPTV. It does this by being effective at tackling bursts of impulse noise (i.e. spikes of electromagnetic interference that are particularly problematic when they appear frequently and at much higher power levels than that of the ordinary background noise) and less interference usually equals better performance / stability. This is can also be used on supporting VDSL2 (FTTC) connections. Sky’s latest broadband routers support this.

* Nitro

We’re still awaiting confirmation from Sky but we believe this can be employed by ISPs that use Broadcom’s DSLAM network devices inside telephone exchanges. Nitro Mode works to increase the throughput on broadband links by compressing the ADSL2+ ATM header, thus requiring fewer bits to be transmitted and potentially giving you the impression of being able to get a faster connection (though the limits of your physical line remain the same).

Broadcom claims that Nitro could help some connections to achieve compressed data rates as high as 30Mbps, although this would depend upon DSLAM setup, line length, the quality of your home wiring and various other factors. For example, an ADSL2+ connection that runs at the near top speed of 20Mbps might be able to receive some information (i.e. uncompressed data) at speeds of around 24Mbps.

As above, this can also be used on supporting VDSL2 connections.

The result of additions like those above should deliver an improvement to Sky’s Dynamic Line Management (i.e. rate adaptation in ADSL/ADSL2+ connections) and general performance. We believe that Sky has actually been using G.INP for several months now (since around Easter time), although Nitro is not something we’ve heard much about before.

Similarly Sky’s network has also semi-recently been improved to tolerate lower noise margins, which use to be more of a problem and could cause some links to drop and thus reduce your line speed. This is just another of the many subtle changes that end-users rarely notice but that can help to improve your connectivity.

Naturally we also wanted to know whether BTOpenreach were planning any similar changes for their own lines, which are used by BT and various other ISPs, and after quite a bit of waiting a spokesperson finally told ISPreview.co.uk that, “we are running a limited trial of Physical Retransmission (G.INP) on a small number of FTTC/VDSL lines, to identify the benefits this capability might provide, but it’s not on ADSL2+“.

We hope to have some more details from Sky Broadband shortly (it’s taken awhile to find somebody with enough technical familiarity for an answer).

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Mark Jackson
By Mark Jackson
Mark is a professional technology writer, IT consultant and computer engineer from Dorset (England), he also founded ISPreview in 1999 and enjoys analysing the latest telecoms and broadband developments. Find me on Twitter, , Facebook and Linkedin.
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15 Responses
  1. Avatar Phil

    So, what the real difference between my own isp Plusnet on ADSL2+ current sync at 17500K (snr of 3dB) with IP Profile rate of 15435K. So, if with Sky ADSL2+ will the sync rate will be much higher with the same snr of 3dB?

  2. In theory you might get slightly better performance and stability on Sky but as ever each line is different and ADSL2+ is so variable that making an apples-to-apples comparison would be very difficult. Not to mention issues like local congestion, traffic management, different hardware choices etc.

    I’ve noticed that the Sky line we have at home has gone from 9Mbps to 12Mbps and become more stable at low noise margins over the past two years but that could be due to all sorts of things.

  3. Avatar Phil

    then no wonder why sky are control themselves not the customer

  4. Avatar cyclope

    For some adsl customer’s, the difference between a 3 & 6db noise margin and availabilty of Fast path on their connections is the difference of that connection being viable to them or not, hence they won’t choose sky even 21cn adsl can be configured by isp’s to suit the customers requirments,

    The bit about there being no one from sky able to explain what nitro is or does says it all really,

  5. Avatar TomD

    Very interesting Mark Jackson, but I heard that Sky won’t lower snr as low as 3. They only do no lower than 7, is that true?

    No, Sky’s version of DLM can take the noise margin down to 3db.

  6. Avatar Alec Robertson

    I assume Plusnet don’t benefit from BT’s improvements?

    • Avatar Ignitionnet

      Every ISP reselling BT’s ADSL or VDSL will benefit. BT aren’t allowed to keep these things to themselves for their own ISP’s use only.

  7. Avatar Roberto

    Too bad DLM on BT can take months to re-adjust a profile back upwards after a minor issue.

  8. Avatar Slackshoe

    To clear up some misinformation here.

    Sky’s DLM can and does target 3db if the line will handle it. This is nothing new, it has been in effect for about a year now.

    Lines on Sky’s MPF platform (SVBN) can be manually set to 3db profiles.
    Line on SMPF can only be manually set to 6db minimum, but DLM can still go down to 3db.

  9. Avatar jamesmount

    Thanks for great information,I have a question, may i Improve the BTs by the help of Sky ?. If yes then How ?

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