The National Broadband Network (NBN) company will be deploying fibre-to-the-distribution-point (FttdP) connections as it rolls out across Australia -- but only for premises that are located more than 1 kilometre from a node.
According to NBN CEO Bill Morrow, fewer than 10 percent of homes are further than 600m from the node, but those with a copper loop stretching from between 600m to 1km will still get speeds of 25Mbps -- the government's bare minimum standard -- on NBN's fibre-to-the-node (FttN) network.
For premises that are 1km or further from the node, FttdP may be utilised.
"If there is a copper loop length that goes too far beyond the 25Mbps capability -- so call that roughly 1km -- then what we would do is first look to see if we can bundle pairs together, because then you get a better attenuation and a higher signal that gives you the higher speeds," Morrow said during Senate Estimates on Tuesday night.
"If that doesn't work, then we could look at the cost of actually pulling fibre down and using what we call fibre to the distribution point, which is still not taking fibre all the way up to the house, but brings fibre closer to the home, to where that copper loop length is much less."
Morrow further explained that the newly available "box" being used as a distribution point will be installed within footpath pits, and will draw power from the set-top boxes positioned inside the homes it provides with broadband.
"What is new, senator, is the boxes that are just now commercially becoming available that are small enough to fit within the pit in the footpath, and that are reverse powered from the home to be able to make that possible," Morrow said in response to a question from former Communications Minister Senator Stephen Conroy.
"That's still fairly new, nascent technology only now starting to be deployed across the globe."
Should FttdP also not be tenable due to distance, homes will get fixed-wireless or satellite connections.
NBN had moved away from a full fibre-to-the-premises (FttP) rollout following the Coalition's election, with the present multi-technology mix angling to provide 38 percent of the population with FttN and fibre to the basement, making use of the existing copper lines; 34 percent with hybrid fibre-coaxial; 20 percent with FttP; 5 percent with fixed wireless; and 3 percent with satellite services.
The company has faced repeated criticism for making use of the slow-speed, 20-year-old legacy copper cable rather than rolling out new fibre all the way inside of homes.
However, NBN on Wednesday revealed that it has been running trials of FttB networks using G.fast technology to deliver throughput speeds of up to 800Mbps over old copper cable.
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 a multi-dwelling unit in Melbourne, 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, NBN 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.
In the UK, meanwhile, telecommunications carrier BT has also been undertaking G.fast trials using old, existing copper -- managing speeds of up to 5Gbps.
On Tuesday evening, NBN revealed that while copper lines between the node and the home will not need to 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.
"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.
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."
Defective cable will also be replaced, with more added where there is not enough to service the homes in a given area. NBN has spent AU$14 million to acquire 1,800km of copper, enough to last the company five months.