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gfast map June 2017

Dark blue: Firm commitments from incumbent: BT (10M), Belgacom, Australian NBN, Swisscom,  Austria, Bezeq Israel, Chunghwa Taiwan, Telus Canada, Telekom South Africa, SK Korea, (U.S.) AT&T, Century, Frontier, Windstream

Light blue: Smaller carriers" Germany, Norway, Finland, Japan

Green: Incumbent likely: Belgium, France, Germany, & Poland  Country by country details. 

DT-VDSL-from-Telekom-via-Golem-20035b was expected for 2016 but wasn't ready, the Germans say. The improved 35b vectored VDSL uses more spectrum to get speeds of 200 megabits or so up to 300-400 meters. That's not close to the 500-800 megabits G.fast can do over short loops but in some cases saves the telco a lot of money. G.fast can't share the wire binder with the old 17 MHz VDSL but 35b can. Deutsche Telekom has millions of the 17 MHz modems they don't want to replace so chose 35b. Unfortunately, the new systems aren't delivering what DT requires.

Philipp Blank of DT tells Ashun Sawall of Golem.de, ""The technology has to be tested and then rolled out. That will not happen overnight. Part of the problem is the Super-vectoring technology itself. The linecards need to be installed nationwide in the multifunctional housings. We must adapt the product portfolio and the product variants in the IT systems. Finally, we do not have any end devices for customers." Tom Stanton of Adtran a major American supplier who also sells to Telekom, does not expect 35b in volume before 2018.

However, at least three vendors claim they are ready to ship the "end devices." The Italians have already installed more than 10,000 ports and are widely advertising the "200 megabits." These are all reputable outfits, but none of them will explain the discrepancy. 

If they are all telling the truth - which I think they are - I can only guess what's going on. I assumed that the Italians selling 200 megabits were using 35b, the only way to get those speeds I know. But when I spoke to them, they told me, "70% of those customers are getting 130 megabits or more downstream." The Italians have very short loops, averaging ~ 250 meters. 35b is designed to deliver about twice the 130 meg they are reporting. Adtran's lab tests confirm the expected results, See my article, below.

The 130 megabit speeds would be consistent with using 35b gear without the vectoring noise cancellation that is designed into the standard. That would typically cut the speeds in half. The calculations to vector dozens of lines are intense, so Huawei and Adtran have moved the vectoring off the line card to an external box. The equivalent vectoring box for G.fast is late. It was promised to customers for mod-2016 but none have been seen in the field. There's a rumor that Britosh Telecom has some external vectoring boxes for their G.fast, now at about 100,000 homes passed, but I haven't been able to confirm that. Alternately, there could be problems at Broadcom, the chip vendor. Broadcom operates with military level secrecy, often not releasing details even months after chips are shipping. 

Deutsche Telecom once was a world technology leader, but in 2017 they are two years behind schedule building a network seriously inadequate for millions of Germans. 

 Here's the August article I wrote with test results from 35b

 

Sckipio 35b and G.fast 350More than a year late but now in acceptance trials at a large European carrier. 8/16 Everything in the article is accurate as far as I know, except the claim "First results" in the title, now removed. A reader just informed me that Fastweb in Italy is actually in production with 35b and there are some results ion Italian websites 8/20 I thought I had "First results" but in fact Alcatel had published results from KPN testing I had missed. Below.

Original: From chipmaker Broadcom to Nokia and Huawei, everyone promised 35b "Supervectoring" for about a year ago.

Now it's here, and Kevin Schneider’s lab tests at Adtran found “mid to high 200’s @ 1,000 feet.”  Talking with Kevin, I didn't sense any major anomalies in his testing at other distances.  Until now, 35b speeds were estimated based on simulations like the chart here. These early test results are very encouraging. The hope is they can move to field trials in Q4 and soon after to deployment.

35b is essentially vectored VDSL 17b MHz extended to 35 MHz. Initially, the industry thought G.fast from close-in distribution points would be the standard upgrade. With volume production and some competition, the price of G.fast equipment will fall to very little more than VDSL. 35b is close to G.fast speeds from around 300 meters to around 450 meters, but much slower for shorter distances.

The savings won't come from a big difference in modem and DSLAM prices down the road. Moore's Law continues to bring chip prices down while performance increases. However, DT won't have to replace millions of 17b modems because 17b and 35b can co-exist in the same binder. Questions remain about vectoring efficiency, especially with older modems, so everyone is anxious to get field results.

When Deutsche Telecom and British Telecom costed out running fiber to the millions of distribution points, they changed plans. BT decided to use G.fast from the existing cabinets, KPN 35b datadropping speeds for many from close to a gigabit to a few hundred megabits. Homes close to the cabinet will get 500-800 megabits, but BT will not run new fiber closer to homes. DT's CTO said they would do G.fast in 2015 but the beancounters said no.  DT has been earning substantially less than they've been paying in dividends. The marketing miracle at T-Mobile U.S. is the only reason DT's CEO still has a job. 
 

Someone, perhaps at Alcatel, realized that DT wouldn't have to replace as many customer modems if they upgraded to a new system that could work with some of the older modems. That's not practical with G.fast, with a line code incompatible with the older modems. They decided to go with the modified VDSL, extended to 35 MHz. 35b sacrifices a great deal of speed but doesn't require replacing as many old modems. In addition, 35b is faster for those beyond the efficient reach of G.fast.  DT signed on, especially after Broadcom promised chips would be ready in 2015.

In theory, the 35b chips should have been an easy design modification, I was told, because they were so similar to the existing chips. If any reader knows what held them up for a year, please let me know. Anonymity assured. 8/20 Update Alcatel's Paul Spruyt's presentation last October said they had 8 trials already underway and four customers, I just noticed. Ten month later, I would have expected some of these to be in production if they hadn't found problems. <end update>

The U.S. and Europe mostly deploy VDSL using 17 MHz, not yet vectored. Many customers get less than 50 megabits downstream, although it's often advertised as "up to 100 megabits."  With vectoring, the Belgacom data is that most short loops see doubled speeds, with most over 80 megabits and many over 100. Belgacom, under heavy pressure from cable, has invested in many cabinets close to customers. DT, AT&T, and Century/Qwest have fewer cabinets, longer distances, and ultimately lower speeds.

17b runs from 2 MHz to 17 MHz; 35b runs from 2 MHz to 35 MHz. The former covers 15 MHz, the latter 33 MHz. That's a 120% increase in spectrum used, so 250 megabits to about 300 meters is plausible. We now have a confirming datapoint. Thank you Gary Bolton and Kevin Schneider for what I believe is the first reported test speed. Adtran in the last few years has gone from reserved with the press to being one of the most helpful companies.

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