Gfast map

gfast map copy


In 2016, looked very promising.
Thousands worked at developing and deploying.
It wasn't enough. 
Most carriers are investing
in fiber or 5G instead.


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, Belgium, Omantel

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

Light Blue: Incumbent likely:  France, Germany, Italy

200-600 meg pretty fast so why hype? British Telecom, despite the BBC and other news reports, did not attain a gigabit with They merely showed that 104 MHz over a protected standard copper line could reach speeds of 786 megabits down 19 meters, something obvious for years from the basic engineering. The substance of is significant so the hype is unneeded.

BT's results were not for is a 300 page specification that BT/Huawei didn't even pretend to support. Many features, such as reverse power, are important and were not implemented. Vectoring in remains totally unproven and will be crucial to any deployment. Several features of are likely to reduce the speed. The effect may be relatively modest but we won't know until they are tested.

Real deployments will probably have to notch out some of the bandwidth, reducing speeds. Interference with terrestrial radio and possibly other things will require not using the full spectrum. 

BT's deployment of will likely be 20-40% slower because they will have to protect their existing VDSL. Most deployment plans will have to forfeit the first 21 MHZ or so to protect the existing VDSL service. BT has VDSL to 82%, according to their press release below, one of the widest VDSL deployments in the world. It would be amazing if they turned all that off and wasted the investment anytime soon. I believe BT is only using 17 MHz for VDSL; VDSL goes to 30 MHz and would therefore require sequestering even more. 

Broadband speeds are almost always measured in one direction but BT is adding upstream and downstream to get to the "Gigabit" headline. is time domain, meaning you can switch the ratio between upstream and downstream in software. But you can't go all the way to 100%, which would not merely prevent upstream use but would block the acknowledgement packets required for the Internet. I believe adding the two directions to get a headline began with chipmakers, who called three year old 100 down, 100 up VDSL "200 megabits" and presented a "breakthru. I heard it first from Broadcom but I don't know if they originated the meme.


   Adtran put out a press release on a related technology that combines VDSL and but I choose not to report it because they didn't have even lab results. Adtran is doing much better in Europe than expected two years ago, taking part in BT's coming trials and winning at least some ports in Deutsche Telekom. 

   The BBC reports "BT said commercial equipment could be available from manufacturers by December 2015." That a useful perspective because several chip vendors have been suggesting revenue from an earlier date. More realistic is that next spring's conference in Paris will show progress and problems continuing. See you there, I hope. and Telecompaper avoided the gigabit spin but most of the mainstream media picked up the story as BT promoted it.


Company creates new research lab at Adastral Park 
BT today unveiled the results of new field trials that show 'ultrafast' broadband - with combined downstream and upstream speeds of up to one Gigabit per second (1000 Mbps) - can be delivered via a mix of fibre and copper.
Previously it was thought such speeds would require a dedicated business linei or a fibre optic cable to be laid all the way from a telephone exchange to a premises, a relatively expensive, disruptive and time consuming process.
BT, which is due to open a new ultrafast broadband lab at its Adastral Park R&D centre in Ipswich, says it is greatly encouraged by the potential of Fibre To The Distribution Point (FTTdp) ‘G.FAST’ technology - where fibre is instead rolled out to telephone poles or junction (footway) boxes located close to homes and businesses.
During the G.FAST trials, downstream speeds of around 800Mbps were achieved over a 19m length of copper, combined with upstream speeds of more than 200Mbps. Impressive speeds of around 700/200Mbps were also achieved over longer lines of 66m, a distance that encompasses around 80 per cent of such connections. As well as delivering ultrafast speeds, the technology also offers the flexibility to tailor the allocation of the total 1Gbps speed according to a users’ needs. 
BT's fibre network - which is being rolled out by its local access network business Openreach – currently passes more than 20 million UK premises using a mix of Fibre to the Premises (FTTP) and Fibre to the Cabinet technology (FTTC).
FTTC, the more common of the two technologies, currently delivers downstream speeds of up to 80Mbps, giving residential customers plenty of capacity to enjoy the online world todayii. Openreach has doubled the speed of this product in recent years and BT believes potential enhancements such as vectoring can improve speeds further.
FTTP, where the fibre runs all the way to the premises, is capable of significantly faster speeds than FTTC but is considerably more expensive to deploy, leading BT to use it in targeted areas where it offers the best solution for the customer.
With FTTdp, the fibre is closer to the premises than with FTTC, meaning the copper link is much shorter. G.FAST technology is then used to maximise data capacity over the copper and uses much higher frequencies, plus advanced ‘crosstalk’ cancellation techniques, to make ultrafast speeds possible.
FTTdp is potentially a more cost effective and simpler solution than both FTTP and dedicated business lines such as Ethernet. This is because less fibre and civil engineering is required. It also has the potential to be less disruptive for the customer given it is likely it could be a “self-install” product with no need for home engineering visits.
Joe Garner, CEO Openreach said: “Our fibre rollout is making a huge positive difference to this country, already helping 82% of people have access to superfast broadbandiii. 
“Businesses obviously demand even greater bandwidth and can already access speeds of up to 10Gbps via dedicated business lines that we provide across the country. But customer needs will continue to change, and that’s why we’re deploying a mix of current technologies as well as testing new ones. We will continue to innovate so that we meet our customers’ needs today, and in the future.”
Dr Tim Whitley, MD of Research and Innovation, BT Group said: “We see G.FAST as a very promising technology with significant potential – that’s why we’re putting some of our best minds on the case to assess it fully in a purpose-built facility.
“BT has a long history of pushing the boundaries in telecommunications, from the earliest days of the electric telegraph to today’s global fibre networks, and it’s crucial that we stay ahead of the curve for the benefit of our customers and shareholders."
Over the coming months BT researchers will use the new laboratory to study the full technical capabilities of G.FAST hardware designed by leading system vendors such as Adtran, Alcatel Lucent and Huawei.
Whilst commercial G.FAST equipment is still immature, there have been determined efforts by the ITU to accelerate the standardisation of the technology, with the approval of the G.9701 recommendation expected in December.
BT has played a proactive role in developing G.FAST standards, submitting over 100 contributions to the ITU-T G.FAST work item.



Notes to editors

i Known in the industry as ‘Ethernet’
ii The Broadband Stakeholders Group predict the average UK household will need 19Mbps by 2023, with the most data-hungry homes requiring around 35 Mbps [Broadband Stakeholder Group Report: Domestic Demand for Bandwidth]. The current UK average broadband speed according to Ofcom is 17.8Mbps.
iii According to the 2014 EU Digital Agenda Broadband Scorecard.
About G.FAST:
In theory, G.FAST enables 1 Gbit/s ultrafast bandwidth access over a twisted copper pair. That’s a significant speed increase compared with VDSL2 access. 
G.Fast Trial Results
2.2-106MHz, Vectored, 10dB noise margin (note the noise margin is the level of protection against external noise on the line).

Copper Line Length

Upstream (Mbps)

Downstream (Mbps)

Total (Mbps)

Short (19m)




Long (66m)




About Vectoring
Vectoring is a technology similar to “noise cancelling headphones”. It’s highly effective at reducing the amount of ‘cross talk’ that can interfere with the speeds over copper wires.