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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 Green: Smaller carriers in Germany, Norway, Finland, Japan

Light Green: Incumbent likely:  France, Germany, 

Alcatel midi coding 330x152Tweaks VDSL2 for more speed, short-range. The main change is that Alcatel proposes using the VDSL2 line code rather than the code. uses larger tone spacing for efficiency at the higher frequencies. (See illustration form Alcatel.) That allows roughly doubling the speed of 17 MHz VDSL. Many of Alcatel's customers used only 17 MHz rather than the 30 MHz allowed in the standard.   
They presumably made other improvements to the standard, so far not revealed. One may be non-linear precoding of the vector signal, which Alcatel tests show more efficient. That isn't in the standard because the committee hasn't been able to decide on the details.
Alcatel's VDSL team, led by Stefaan Vanhastel and Paul Spruyt, is one of the best in the world so they have some other tricks.
Here's Alcatel's explanation. Note they compare Vplus to 17 meg VDSL2, not the 30 meg in the standard. 


  • Vplus delivers speeds exceeding 300Mbps on a single copper pair
  • Vplus offers unmatched throughput, density and cost on 200-500m copper loops
  • Vplus is a simple extension of existing standard VDSL2 vectoring technology

Vplus is a perfect match for operators who need to deliver the highest possible speeds in a cost-effective way on medium-length loops. Vplus is a new technology that

  • Delivers aggregate speeds of 200Mbps and more over traditional copper telephone lines at distances up to 400 meters, and 300Mbps on loops shorter than 200m
  • Extends the frequency range used by VDSL2 17a vectoring to 30MHz to achieve these higher speeds
  • Can be mixed with existing VDSL2 17a deployments to fill the gap between VDSL2 vectoring (100Mbps aggregate at 700m) and (500Mbps+ aggregate at 100m)
  • Offers higher speeds (up to double) compared to VDSL2 on loops shorter than 500m
  • Offers longer reach (higher bit rates beyond 200m) and higher density (100-200 subscribers) compared to
  • Lowers operator costs compared to


Figure 1 illustrates the typical performances you can expect from VDSL2 vectoring,, and Vplus.

Aggregate bit rates (upstream + downstream) are used for a fair comparison between technologies. performance is based on the ITU-T G.9701 standard (approval of which is expected in December 2014), i.e., using up to 106MHz of spectrum, and excluding VDSL2 (17a) spectrum to illustrate a mixed technology deployment.

VPLUS longer reach than, high speeds than 17A vectoring.

Figure 1. Vplus fills the gap between VDSL2 vectoring and

In terms of bit rate, Vplus fills the gap between VDSL2 vectoring and At loop lengths between 200 and 400 meters, Vplus delivers 200+Mbps and outperforms both VDSL2 vectoring and

At shorter distances (less than 200m) Vplus does not match’s speeds, but still delivers up to 300Mbps. So even on short loops, Vplus makes a strong case for operators who need to deliver up to 300Mbps.

On longer loops, Vplus falls back to VDSL2 17a vectoring performance.


As a general rule for FTTx, the deployment cost per subscriber and bit rates increase as the “x” moves closer to the end-user. As seen in Figure 2, each xDSL technology has a “sweet spot” area in which it performs best. Choosing the right technology to hit the cost, density and bit rate targets is the goal. uses a very wide frequency range, up to 106MHz (to be compared with 17MHz for VDSL2 17a) to deliver 100s of Mbps (up to 1Gbps). This very wide spectrum and the associated very high bit rates require much more processing resources for the transceiver and vectoring functionality than VDSL2, limiting the achievable density of a design.

VDSL2, VPLUS and G.FAST sweet spot pf cost per subscriber, density and bit rate target.At the same time, these high frequencies are only effective over very short distances (typically 250 meters or less). Consequently, nodes will have a very low port density – typically 16 subscribers or less per system – and will get deployed very close to the home. This results in a high CAPEX cost per user. On the other hand, will enable a faster adoption of FTTH services, avoiding the need to rewire every front yard and multi-dwelling unit.

In contrast, existing VDSL2 17a vectoring is optimized in terms of bit rate, density and cost for FTTN deployments with loops in the range of 500m to 1000 meters. Since VDSL2 17a is widely deployed today, it offers a fast and cost effective upgrade path to 100+Mbps with vectoring.

Vplus, with its 30MHz spectrum, supports both longer loop lengths (200Mbps over 400 meters) and denser solutions (up to 200 subscribers) compared to This makes Vplus the best solution for high-speed FTTN/FTTcurb deployment over medium loop lengths.

In fact, Vplus reach is a very good match for many existing FTTN deployments, and can provide a quick and easy upgrade path for operators that are already deploying VDSL2.


Using frequencies up to 30MHz for VDSL2 is of course not new. That is exactly what the VDSL2 30a standard profile does. However, the 30a tone spacing is different from the 17a tone spacing preventing cancellation of crosstalk between 17a and 30a lines. This makes upgrades of the existing 17a deployments to 30a unattractive as it would require a full swap of the VDSL2 CPE installed base.

Figure 3. VPLUS allows mixed vectoring with VDSL2 17A

Vplus overcomes this limitation by using the same tone spacing as 17a. This allows vectoring across Vplus and 17a lines, and thus mixed deployments and a smooth introduction of Vplus. Since only tone spacing changes, existing 30a band plans can be reused. Alcatel-Lucent has brought Vplus to the ITU for adoption as a straight forward amendment of the VDSL2 standard.

- See more at:

The Site for gfast 230 News
A remarkable 400 people attended the very strong Broadband Forum BASE events in Berlin and Las Vegas. Trevor confirmed BT would pass the million this year. Cioffi projected “Waveguide DSL” could carry 10 gigabits a kilometer as well as a terabit 100 meters. Werner sees a 4X improvement in upstream with cDTA. Much more in next issue.

Deutsche Wants a Gigabit, Finally Realizes 50 Meg Isn't Enough
Deutsche Telekom is finally realizing that 50 megabit DSL won't make it against gigabit cable. VP Franz Seiser is blunt. "We must change radically, become disruptive and, above all, throw away things," he proclaims at BBWF. After years of DT insisting 50 megabits is plenty, we now hear "it is about Gigabit products" from DT's Robert Soukup.  
    A lucky building in Frankfurt will receive 500+ megabit service as ultra-conservative Deutsche Telekom experiments with Soukup told BBWF, "We're going to have a field test in Frankfurt with and Fiber To The Building (FTTB.) We will know by the end of the year if this is the right way to go." Hint to Soukup: Yes it is. is working well at a dozen telcos I;ve talked to.
     The details are surprising. DT is going for CORD, Open Source, Calix, and Radisys.

*** The new Telebyte Guide to Testing Gfast follows the Broadband Forum IR-337 Gfast test specification, the same used by the University of New Hampshire (UNH-IOL) for Gfast certification testing. Free download (ad) It is the best technical guide to  I have seen. Grab it. Dave

1.6 Gig in Sckipio-Calix Test
A telco tells me they are getting impressive early results from the Calix 48 port DSLAM with the new Sckipio 212 MHz chips. There still is work to do but this is encouraging. 
    Carriers want DSLAMs with more than 16 ports to reduce the deployment costs from the basement or larger field cabinets. Speed matters to the marketing side of the company; AT&T's CEO believes he must offer a true gigabit to match cable. (They've been getting ~750 megabits with first generation chips.

*** Self-Healing Wi-Fi With ASSIA Real-Q 
Beyond-the-Box visibility and control extends quality-of-experience (QoE) beyond the gateway to the end-user device for every device in the home. Based on ASSIA technology, proven across 80 million subscribers (ad)

Reverse Power 4 Port DSLAM for Australia
Australia is connecting 1M homes to, some with a Netcomm distribution point mini-DSLAM. It's a small unit designed for pole or pit mounting. It's waterproof, pressure proof, and temperature resistant. Their matching home modem is bittorrent friendly, with two USB ports for a hard drive dedicated to sharing.
     A reverse power unit at the customer, the NDD-0100-01, can save the cost of bringing power to the DSLAM. They don't expect many orders until the second half of 2018, as nbn is waiting for the second generation chips. Netcomm demonstrated RP with BT Openreach in August.

*** Sckipio's Three advances are taking to the next level. (ad)

Australia Makes it Official: to Million Plus
No news here. In September, 2015, I reported Australia's nbn Going This June. I reported the million home fiber to the curb (kerb?) was beginning. Unfortunately, they are no closer to figuring out where to find the needed $10B to $20B to cover the cost overruns. Instead, the parties are battling in Parliament about who is to blame.

2 Bonded 212 Lines = 3 Gigabits
Sckipio at BBWF is demonstrating 3 gigabits down, nearly a gigabit up, over two phone lines, bonded. Twice the bandwidth (212 MHz instead of 106 MHz) times two lines is fast. Sckipio does great demos; at CES, they showed first generation chips delivering almost 1 gig upstream.
    “Sckipio is pushing Gfast to astonishing speeds with production silicon,” CEO David Baum proclaims. Calix is using the SCK23000 chipset in their 48 port gig+ DSLAM at the show.

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