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gfast map nov

Dark Green: 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, Belgium, Omantel

Mid Pink: Smaller carriers in Germany, Norway, Finland, Japan

Light Green: Incumbent likely:  France, Germany, Italy

British-Telecom-noise-dataAT&T leading the efforts for an updated standard. Field tests of current G.fast gear have seen speeds of 400-700 megabits downstream, not the gigabit promised in early pr. 400-700 is plenty for almost everyone but the marketing department is worried. Cable is going to one and two gig (shared.) Google is just one of hundreds around the world offering a symmetric gig. The engineers have marching orders: get our G.fast speeds to a true gigabit ASAP!

Fortunately, the engineers are confident they can reach a gigabit.The ITU group already is working on a second appendix to the G.fast standard, aiming for 2016. A chip CTO tells me it will be easy to do more efficient coding (non-linear precoding) and transmit more bits for a given frequency (constellation.) Those two changes he believes enough to do the trick. 

Trevor Linney of BT is running the most advanced tests of G.fast, connecting 4,000 homes. He reports "Our research shows that even more capacity can come from copper."

He also predicts more bits per tone and a lower noise floor (i.e. <-150dBm/Hz). He supports that with the test data in the illustration.  Increasing the transmit power, perhaps to 8dBm, is also under consideration. 

ITU-T agreed to specify non-linear pre-coding in an amendment to G.9701. Dong Wei of Huawei presented the data below at the excellent Upperside Conference. Interference is different at different frequencies a better coding scheme can make a large difference. Simulations show a difference of 100-300 megabits. Wei presented three different possible coding schemes, the three upper lines in the graph. Deciding on which is right for the standard can be challenging, one reason standards take time to develop. 

Bonding two lines doubles the speed, also new to the standard.

Non-Linear Precoding Huawei

 

 

 

ITU-T agreed to specify non-linear pre-coding in an amendment to G.9701. 

The Site for gfast 230
 

G.fast News

I’m still working through remarkable presentations from the Broadband Forum events. Michael Weissman, Bernd Hesse and team did a remarkable job choosing the speakers. http://bit.ly/BBFBASE

Deutsche Telecom: 35b Supervectoring Delayed to 2019 http://bit.ly/35blater
Broadcom is now over 3 years late. DT briefed German reporters after their financial call and revealed 35b was now delayed until 2019. 35b should deliver 200+ meg downloads 500-600 meters, a crucial tool for DT, which is losing share to cable. Cable now covers about 70% of Germany and is expanding. DT now only offers 50-100 megabit DSL while cable is often 400 megabits, going to a gigabit. 

The problem is software; the hardware is shipping and supposedly will work. DT says 35b is not ready to turn on. Broadcom in 2015 said 35b was in "production" in the press release below. Alcatel in early 2016 said to expect complete systems very soon. "35g is very similar to 17a so there should be little delay."

Broadcom's problems are leading major telcos and vendors to have a plan B, using Sckipio G.fast. DT itself is planning extensive G.fast deployments in 2019, mostly in apartment buildings. http://bit.ly/35blater

Gigabit 100 Meters - Unless the Wires are Lousy http://bit.ly/gflousy
Speeds are fine, "Unless there's a line problem." I've been reporting for three years that ~10% of lines have problems. In the chart by Rami Verbin of Sckipio, he finds G.fast goes ~130 meters on good lines. Poor lines have about half the reach. 

His chart roughly matches the reports from Swisscom, Belgacom, and England for both G.fast & vectored DSL. The 10% with problems can cause the majority of the line-related complaints to support. The angry customers drive up cost.

Rami's solution to reach the gigabit is bonding, supported on the Sckipio chips. Verbin made some additional points:

  • 4 gigabits is possible by bonding two decent 2 gigabit lines.
  • Even in a service from remote cabinets, ~25% are close enough to get a full gigabit."
  • cDTA and iDTA are practical ways to deliver much higher upstream by switching some bandwidth from downstream to upstream only when needed.
  • 35B will probably be similar but Deutsche Telecom doesn't expect to deploy until 2019. http://bit.ly/gflousy

AT&T Wants Coax 2-5 Gigabit G.fast. Very Soon. http://bit.ly/ATTCoax
AT&T faces intense competition from cable, talking about 10 gigabits in both directions. (Cable will only be 1 gig down, ~100 meg up, until ~2021.) AT&T wants something to brag about as well.

AT&T gained millions of lines of coax as part of the DirecTV deal. Alcatel and Huawei are leading the development of G.mgfast. That uses 424 MHz, full duplex, to achieve ~2.5 gigabits in both directions. The reach on telco twisted pair is only about 30 meters. On coax, those speeds can probably extend far enough to service most apartment buildings. Using 848 MHz, speeds can reach 5 gigabits. The ITU standards group has been aiming for 2019-2020 for G.mgfast, too slow for AT&T's marketers. David Titus wants a high-speed standard for coax "early in 2018." He believes that is "doable."http://bit.ly/ATTCoax

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