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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, 

acoustic couplerStanford wireless guys and CableLabs are exciting the press by going full duplex. Alcatel has demonstrated a prototype. It was described in a press release with BT 

XG-FAST, a potential future development of the technology, is in the early stages of lab testing, but has exceeded expectations in trials at Adastral Park, BT’s global research and development campus in Suffolk, and Alcatel-Lucent’s labs in Antwerp.

It delivered aggregate speeds of 5.6Gbps over 35 metres of BT cable, a record for full-duplex data transmission over a standard single BT line at this distance. The technology also performed well over longer distances, with aggregate speeds of 1.8Gbps over 100 metres; a significant result, as most UK homes are within this distance of their local distribution point, be that a pole or footway box. (below, full duplex excerpt from an article by Jochen Maes and team.) 

At the start of the work, they investigated the possibility of sending data both upstream and down in the same frequency. It wasn't included then. There are trade-offs: complexity, reach, robustness.  

A respected DSL engineer confirms to me DSL can also go full duplex. He emails:

ADSL1 had an echo-cancelled mode that was an option, but the crosstalk into other lines was a problem for full duplex. This was abandoned in DSL for many generations after that.  With vectored systems, it is indeed now possible again to do a full-duplex or G.vector, but the power and cost would increase significantly.  So, yes, could be 2x faster.

Usable speed doubling is unlikely given variable upstream and downstream.

Traffic might be 80% downstream and 20% upstream. Even if the full duplex works perfectly much of the available upstream is not of use to the consumer.

I just sent a note to chip engineers asking, "If a large customer wants full duplex, how long would it take and how much would it add to the cost?" I doubt anyone will go on the record but I welcome all thoughts. 

Going full duplex is not new. 30+ years ago, full duplex technology and echo cancellation were used to create 9600 baud modems. Moore's Law allows faster processing today and some engineers are optimistic. (At least one I respect remains unconvinced.)

Stanford and Columbia teams are looking to bring FD to market for wireless. Kumu Networks is extremely hopeful that full duplex is ready to work in wireless networks, although fitting into a mobile phone will be a challenge. It's a spinoff from the labs of Stanford Professors Sachin Katti and Phil Levis. Harish Krishnaswamy at Columbia has developed chips. 

AT&T and other carriers, facing one and two gigabit cable, are pressing hard for gigabit speeds to advertise. My guess is they'd spend $5/home more for the speed just for the promotional value, maybe more.. Century just confirmed AT&T's experience that promoting higher speeds has a "halo effect" on selling current services. So they announce "70 cities" for gigafiber even if they have passed only 2-3% of homes. That's also why  nearly every telco seems to be announcing 5G "tests." I think Verizon will find something to call 5G and put some boxes in the field in the nest 18 months.  It isn't really ready.

Of course, almost no one can point to any common application that even maxes out 200 meg, except heavy downloading.

From IEEE Communications Magazine — Communications Standards Supplement • December 2015

Full Duplex Transmission

In multi-user DSL deployments, simultaneous upstream and downstream communication on identical frequencies is made impossible by near-end crosstalk at the customer side of the network. When used as a single-subscriber technology, XG-FAST will have no NEXT between CPEs, hence allowing for simultaneous upstream and downstream on the same frequency, which we will refer to as full duplex, doubling the spectral efficiency compared to currently used time or frequency division duplexing schemes. 

It requires an analog hybrid at the transceivers that attenuates the transmit signal to the level of or below that of the received signal, not to substantially increase the required dynamic range of the analog-to-digital converter. The residual echo signal is further removed digitally using vectoring techniques. 

Note that compared to TDD, full duplex transmission also allows a reduced latency and framing overhead. E Communications Magazine — Communications Standards Supplement • December 2015

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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