?10-15% performance increase for British Telecom. Last year, I reported that G.fast could run 100 megabits faster if the frequencies below 21 MHz didn't need to be protected. British Telecom has been experimenting with reducing the carve out to increase the speed of their new offering. ASSIA now is proposing to go further, with coordinated Dynamic Spectrum Management to minimize the spectrum used by the VDSL. G.fast could then take advantage of the unused spectrum and increase the speed to the consumer. One box would coordinate all the lines, allowing faster speeds to both the VDSL & G.fast customers.
We don't have test data yet so the improvement can only be estimated. One estimate is 100 megabits more or 100 meters longer reach, but for now I'm being cautious and saying 50+.
The amount will vary depending on the actual lines in each binder but should be significant. ASSIA, Alcatel, and Huawei offer DSM systems that presumably could be rapidly configured for the new functionality.
The kicker, as usual with vectored DSL, is that competitors must work together. Diplomacy is difficult, even though this is an obvious win-win for everyone. DSM constantly monitors the actual lines. Often, the required speeds can be achieved with lower power/different PSD mask. That in turn reduces the interference and allows other lines to run faster.
DSM has been part of the standard for a decade and works well. The original DSL standard was deliberately conservative because in the 1990's, there was no reliable way to do real time measurements. When DSM reached the field a decade later, both speed and reliability significantly improved. This was particularly important for telcos selling TV over broadband; dropouts and buffering went down considerably.
Current G.fast systems start at 21 MHz, to provide a margin of safety for VDSL that can run up to 17 MHz. Eliminating the VDSL - with fair concessions from the incumbent to the other operators - is the right move for better service to consumers. Once vectoring was developed, DSL became a natural monopoly. That's frightening to regulators, who prefer to rely on competition.
Competition worked very well a decade ago, when 6-10 competitors drove French and British prices to half the level of the U.S. As the market eliminated all but three or four companies, the benefits of competition started to erode. In Britain the last five years, prices have gone up 25-40%.
Some of the increase was due to Ed Richards at OFCOM being a nice guy but not having the courage to do what needed to be done. BT has a monopoly on lines in half the country and a friendly cable company which likes to raise prices. Richards never should have allowed BT to raise line rentals while costs went down. Sharon White looks stronger, but hasn't evolved a policy effective with weaker competition.
(Structural separation of BT is not the answer. Most of the benefits will go to the other telcos, not the consumer. What Britain needs is a requirement that the carriers deliver a robust Internet at a fair price. Separation is not likely to deliver that.)
A thoughtful regulator would eliminate the unbundled lines as G.fast rolls out. Technology has made that obsolete. Consumers are paying the price as they are running 100 megabits slower than they should. Competition wouldn't disappear but move to a different level. ISPs could continue to compete on services, offerings, the backbone, and especially how well they treated the customer. Eliminating wire unbundling is good for consumers iff the regulator sets an appropriate price for the bitstream unbundling. Jochen Homann in Germany tried to do that but couldn't resist the political power of DT. Prices in Germany are going up by $2-$5/month.
Unbundling in England is going to die in a few years no matter what the regulator does. Cable will run at over 400 megabits and BT's G.fast is aiming for 300 meg. The others will be offering less than 50 meg to most. They won't be competitive. Almost certainly they will lose customers until they become uneconomic and get out of the business.
Holding back the sea is not easy.
Important conflict of interest note: I'm on the Advisory Board of ASSIA and have done significant (five figure) work for them over the years.