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BT attains 5Gbps over next-gen G.fast

BT is claiming it has achieved trial speeds of 5Gbps over G.fast fibre-to-the-node technology, which it says is faster than most FttP broadband connections.
Written by Corinne Reichert, Contributor

UK telecommunications carrier BT has announced at the Broadband World Forum in London that its trial of the new G.fast standard has seen it attain speeds of up to 5Gbps over copper lines.

G.fast, used to provide high-speed broadband on networks that stop short of rolling fibre all the way to the premises -- namely, fibre to the basement (FttB), fibre to the node (FttN), and fibre to the distribution point (FttdP) -- is the next iteration of DSL after ADSL and VDSL.

Approved by the International Telecommunications Union (ITU) in December 2014, G.fast is a mix of DSL and fibre elements, and provides "fibre-like speeds" from up to 400 metres away, with aggregate speeds of up to 1Gbps.

By using XG-Fast, Alcatel-Lucent's next generation of G.fast, BT achieved throughput of over 5Gbps on 35m two-pair copper cable, and 1.8Gbps over the distance of 100m of two-pair copper.

According to BT, these speeds are faster than most fibre-to-the-premises (FttP) broadband connections.

BT began rolling out G.fast broadband technology in Huntingdon and Newcastle in August, promising speeds of up to 330Mbps -- "more than 10 times the current UK average", according to BT -- to the 2,000 premises being connected.

Premises on the trial are now reaching between 300Mbps and 500Mbps download speeds, with BT set to launch wide-scale commercial availability of G.fast next year.

"If trials like the one in Huntingdon prove successful -- and if UK regulation continues to encourage investment -- Openreach aims to start deploying G.fast in 2016-17 alongside its fibre-to-the-cabinet and fibre-to-the-premises services," BT said.

BT plans to deliver speeds of up to 500Mbps to 10 million homes across the UK by 2020, extending this to 20 million households by 2025. The Australian government, meanwhile, has maintained its significantly lower benchmark of delivering at least 25Mbps to all homes by 2020.

Alcatel-Lucent has undertaken 34 G.fast trials with various operators across the globe, including the world's first G.fast commercial deployment with Chunghwa Telecom in Taiwan.

BT's trial speeds come off the back of news that the company rolling out Australia's National Broadband Network (NBN) has been trialling G.fast FttB technology in Melbourne, attaining throughput speeds of 800Mbps.

The 20-year-old CAT-3 copper telephone line being used in the trial runs 100 metres from the basement to the fifth floor of the multi-dwelling unit, with an apartment on that floor reaching speeds of 522Mbps down/78Mbps up during a trial last week. The company claims that it has been consistently achieving this total throughput of over 600Mbps during the course of its trial.

However, the company also pointed out that during the trial, it has had to turn on VDSL masking in order to avoid interference with other VDSL lines; once the 'full spectrum' is turned on, speeds should reach almost 800Mbps.

Results from NBN's National Test Facility have achieved throughput of 967Mbps on copper stretching 20 metres -- the typical distance from a residential lead-in to a street pit -- and 800Mbps on copper running 100 metres.

According to NBN, Australian retail service providers (RSPs) will begin testing G.fast capabilities next year, with commercial services to launch the year after.

Following the Coalition's election at the end of 2013, NBN moved away from Labor's full FttP rollout to the present so-called multi-technology mix (MTM), which proposes to cover 20 percent of the population with FttP; 38 percent with FttN and FttB; 34 percent with hybrid fibre-coaxial (HFC); 5 percent with fixed wireless; and 3 percent with satellite services.

There have long been criticisms that FttN would be a slower-speed network than Labor's FttP, with Shadow Communications Minister Jason Clare arguing that the copper being used for the network is so old that replacement is necessary.

"I have been talking to some contractors in the field recently to get a feel for how good the copper network is, and how much of it needs work or needs to be replaced. They have told me that NBN's working assumption is that 10 percent of copper pairs in fibre-to-the-node areas will need remediation," Clare said last week.

"But in places like Newcastle and the Central Coast, closer to 90 percent of the copper pairs have needed work. In some places, the copper is so bad it has to be replaced. One contractor told me in Newcastle and the Central Coast, 10 to 15 percent of the copper lines are having lengths replaced."

On Tuesday evening, NBN revealed that while copper lines between the node and the home will not be replaced, the company will need to add or replace copper between the node and the pillar where necessary in rolling out its FttN network.

"We have to put new copper in to run to the pillar that serves all of our homes from our node to that pillar. And that could range in distance between right next to each other ... it is a short section, but it is new copper that has to go in the ground that doesn't exist today," NBN CEO Bill Morrow told Senate Estimates.

Morrow explained that putting in new copper is necessary in order for the company to be able to gain access to the nodes to deliver broadband to the homes.

"So today, there's a feeder copper cable that goes into our neighbourhood entry point, where a pillar stands up out of the street, usually near the footpath. We want to access that pillar, because it has a distribution network that goes to each one of our homes. Now, we want to access it with our optical technology that we're delivering with fibre to the node, but ... if it is across the room or down the block, we have to put copper to be able to get to that node," Morrow said.

"There is copper there that we're not going to use."

According to Morrow, copper has to be used rather than fibre-optic cable in certain cases depending on the distances being covered.

"We're going to run fibre to wherever our node can be, ideally right next to the pillar. But that ideal is not always something that we can do. So when it has to be a couple of homes away, or half a block away, then we need to be able to access the copper that's in the pillar and tie it to the electronic sets in our node, and we wouldn't run our optics to do that, because if we could do that, we would stand the node up next to the pillar, so we've got to extend the copper over to the node."

Morrow added that defective cabling could also be replaced, with more copper also added where there is not enough to service the homes in that area.

"The other area to where we could be putting copper... is that if there are defective joints that are out there that have a trouble rate that's too high, we'll need to go ahead and make that investment to replace that joint as it stands," the chief executive said.

"And then in the other case that I mentioned, if it turns out that there's not enough pairs going down the street to be able to serve all the homes that are there, then we may actually have to add pairs in that path to be able to get to each one of the homes."

He said that NBN has spent AU$14 million to acquire 1,800 kilometres of copper, enough to last the company five months.

Morrow's comments came on the heels of those made last week by NBN that it has not had to replace any of the legacy copper between node and home in installing its FttN network, with end users able to achieve high speeds while relying on existing infrastructure.

"So far, in our FttN deployment, we have not had to replace any copper or perform any substantial remediation work to the copper running from our street cabinets to end-user premises," Tony Brown, the public affairs manager at NBN, said in an often amended blog post originally posted last Thursday.

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