The company rolling out Australia's National Broadband Network (NBN) has announced a trial of G.fast fibre-to-the-basement (FttB) technology, attaining throughput speeds of 800Mbps.

G.fast, used to provide high-speed broadband on networks that stop short of rolling fibre all the way to the premises -- namely, 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.

"We are very excited about the potential that G.fast offers; it has the potential to give us tremendous flexibility in delivering very fast speeds to end users in a wide range of different environments," said Tony Cross, chief architect of NBN.

"This is fantastic news for our end users, as G.fast can deliver exciting new services such as symmetrical speeds, which will offer new possibilities for both residential and commercial end users. We look forward to working alongside our global peers to further develop our understanding of this great technology."

Customers whose premises are located in an FttN/B/dP-designated area will see fibre-optic cable rolled out to a node nearby, with existing copper lines then delivering the broadband into their premises.

NBN has been using Alcatel-Lucent G.fast equipment -- specifically, the 7368 Intelligent Service Access Manager (ISAM) Optical Network Terminals, 7368 ISAM CPE with integrated reverse power, and 5520 Access Management System -- for the trial in Carlton, Melbourne, as well as a 20-year-old CAT-3 copper telephone line from the distribution point.

The copper runs 100 metres from the basement to the fifth floor of the multi-dwelling unit (MDU) being tested in Carlton, 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.

Although only one apartment has been tested on the connection so far, the company claimed that vectoring will maintain the same high speeds as more apartments are hooked up.

In the basement itself, the service reached speeds of 743/220Mbps -- throughput of over 950Mbps -- during a test last week.

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 100m.

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

"In the first half of 2016, we will look to move to our first trials including our RSP customers," the company said.

"We anticipate being in a position to launch commercial G.fast services from a technical perspective in around 2017."

NBN also revealed that the throughput is flexible and can be adjusted depending on how much upload and download a particular end user needs. For instance, a throughput of 800Mbps could facilitate 700Mbps down/100Mbps up or be split for 100Mbps down/700Mbps up, depending on the user's needs.

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

"Delivering better broadband to more Australians will be a key factor in preparing the nation for future innovation and growth opportunities. We share NBN's ethos that no one technology fits all, especially for a deployment such as this one," said Sean O'Halloran, president and managing director of Alcatel-Lucent Oceania.

"As a leader in fixed ultra-broadband access, we can offer operators a mix of fibre and copper technologies that they can use to deploy broadband more quickly and cost effectively, while planning for the future. This trial represents a growing momentum as more service providers recognise the potential of G.fast."

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

BT said that should the experiment be a success, it would be rolled out to the entire country.

"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.

CHT has also launched commercial G.fast services in Taiwan, speeding up its own high-speed broadband network by forgoing fibre to the premises (FttP).

"CHT has announced that they will now move away from an all-fibre approach and instead begin using existing copper for the last mile of the network, utilising G.fast technology to deliver speeds of up to 500Mbps by year end," Tony Brown, the public affairs manager at NBN, noted in a blog post in June.

Shadow Communications Minister Jason Clare last week said that he expects NBN to follow suit and move from FttN to either fibre to the curb or FttdP using G.fast technology.

"NBN has also recently revealed that they are about to trial G.fast in the lab," Clare said at CommsDay Melbourne Congress.

"I think it is likely that sometime between now and the next election, the new minister will announce that NBN will be rolling out fibre to the curb using G.fast.

"It will be evidence that Labor was right, and Malcolm Turnbull was wrong."

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 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."

According to Brown, however, NBN has not had to replace any of the legacy copper in installing its FttN network, and claims that the copper is in a poor, aged state are "misleading, or just plain wrong".

"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 a blog post.

"What we have been doing is necessary work compressing copper at the street pillars (located next to our street cabinets) in order to enhance network performance. Conducting this type of work does not constitute 'replacing the copper' -- the lines themselves are being left in place -- all we are doing, for example, is replacing two lots of 100 pair cables with a 200 pair cable in order to free up ports."

The MTM NBN is expected to cost up to AU$56 billion in peak funding, and is due to be completed in 2020. Last week, NBN revealed in its three-year construction plan that the network will reach 9.5 million homes by September 2018.

The plan involves readying NBN access or having construction under way by September 2018 to 2.8 million premises in New South Wales; 2.5 million in Victoria; 1.9 million in Queensland; 970,000 in Western Australia; 750,000 in South Australia; 72,000 in the Northern Territory; and 134,000 in the Australian Capital Territory.

The wide-scale rollout of HFC and FttN services was approved by the Australian Competition and Consumer Commission (ACCC) in June, with a revised AU$11 billion deal allowing NBN to take ownership of Optus' HFC network and Telstra's HFC and copper assets.

NBN switched on its FttN network last month, claiming that trials in Belmont have seen customers achieve download speeds of up to 100Mbps.

NBN is planning to connect 500,000 premises with FttN by mid-2016, growing this to 3.7 million by June 2018. More than 20 RSPs, including Telstra, Optus, TPG, M2, Exetel, AAPT, SkyMesh, and Harbour ISP, have already signed wholesale broadband agreements to sell FttN NBN services to end users.

Prime Minister Malcolm Turnbull also claimed that it would cost less and be delivered faster than Labor's full FttP rollout.

"The corporate plan shows that the multi-technology mix remains the most cost- and time-efficient means of completing the NBN, delivering upgrades six to eight years sooner, and at around AU$30 billion less cost than an all-fibre to the premises alternative," the former communications minister said in a joint statement with Finance Minister Mathias Cormann in August.

Clare admitted that should Labor come into power at the next election, he would not be able to reinstate a full FttP network.

"I can't fix the mess this government has made with the flick of a switch, or pull out every node or stop all the work NBN is currently doing without potentially causing more problems and wasting a lot of sunk investment," Clare said.

"If anyone thinks I can just click my fingers the day after the election and we can go back to the way it was, they will be disappointed."

However, he did promise that the FttN rollout would be canned under Labor.

"Fibre to the node will be gone. It's not a question of if this will happen. It's when it will happen and how it will be done," he said.

"If you vote for the Labor party at the next election, you will be voting for more fibre. For more details you will have to wait until a bit closer to the next election."