After a few years of getting PR emails expounding the virtues of DLM systems around the world that ASSIA have provided a court case has seen BT found to be infringing two ASSIA patents with its NGA DLM system.
"For several years, British Telecom has used a system called “RAMBo,” which is short for Rate Adaptive Management Box, to provide Dynamic Line Management (“DLM”) to optimize broadband speeds for its DSL broadband services. The “BT Infinity” superfast broadband service is provided on BT’s Next Generation Access (NGA) network. UK courts found that the DLM system used to manage BT’s NGA network infringes two patents owned by ASSIA, Inc., a leading provider of software solutions for broadband access networks. The courts ruled that BT would have to stop using the NGA-DLM system or pay ASSIA £250,000 per week until the system is modified to make it non-infringing. ASSIA has been notified that BT discontinued use of the NGA-DLM on Friday, 21 November. ASSIA believes that this action will have a negative impact on BT customers’ quality of service and speeds."Extract from ASSIA press release
The presumption we are making is that the removal of the DLM refers to JUST the Openreach FTTC based services and will thus affect all providers, not just Infinity. The wording NGA-DLM is a bit confusing since in some circles WBC ADSL2+ is called NGA, and an enquiry has gone out to BT to confirm which system has been turned off.
Paying the penalty while continuing to run the system would be the same as NOT installing another five or six fibre cabinets, or the equivalent of adding around 30p per month to every FTTC connection (remember that the wholesale price is £8 to £10 per month).
While ASSIA is keen to say that turning off the service will lead to a degradation of service, it is very much an unknown as to how many will be affected. There is a school of thought too that the DLM is often too harsh and increases interleaving or descreases speeds too much, so while some may see their line start to flap around more, others may see speeds improve at the expense of the occasional re-sync. The main aim of any DLM system is to avoid a line trying to sync at a high speed and then re-syncing two minutes latter, i.e. flapping about.
An interesting aspect is that it looks like Sky or TalkTalk use the ASSIA DLM system as the report talks of five million lines using the system in the UK, which has to be referring to ADSL2+. For now BT is either working furiously to create a new DLM system and avoid the penalty or will end up buying the ASSIA system, or we might discover that the problems are small enough that giving providers manual control for speed capping may be enough.
Update 27th November 2014: We have received a statement from BT which is reproduced in full below, and tells a slightly different story to the ASSIA release.
"BT has been defending a claim brought by ASSIA since November 2011. They had asserted three patents against BT but during the proceedings, they had to narrow their allegations and withdraw one of these patents entirely.
In January 2014, the High Court found BT was infringing on only a minor part of one patent, and the Court of Appeal, whilst invalidating the majority of the claims of ASSIA's other patent, ruled that BT's network infringes what remains of the other patent.
Although BT was disappointed with the ruling, we have made minor changes to our programming which means these two decisions have no material effect on the operation or performance of our networks."BT Statement on DLM ruling