NBN finally launches DOCSIS 3.1 across HFC network

DOCSIS 3.1 technology will double the downstream capacity across the hybrid fibre-coaxial network, with NBN saying it is focused on improved experience rather than faster speeds.

A technology upgrade to make hybrid fibre-coaxial (HFC) services on the National Broadband Network (NBN) capable of gigabit speeds has finally been launched, with DOCSIS 3.1 going live across the network in a staged process.

Almost a year after announcing that it would launch DOCSIS -- Data Over Cable Service Interface Specification -- 3.1 in late 2018, NBN on Wednesday confirmed that the upgrade has gone live as it ramps up its HFC activations following the network cease-sale.

According to NBN, DOCSIS 3.1 increases capacity by allowing the use of higher-range spectrum, rather than needing to increase capacity by adding more nodes to handle more premises.

"Using technology from our HFC technology partner Arris, NBN Co is planning to deploy DOCSIS 3.1 technology across the vast majority of the NBN HFC broadband access network by 2020 in both the downstream and upstream directions," NBN said.

"As DOCSIS 3.1 is brought onto the network on an area-by-area basis, most end users should have immediate access to the technology as their existing NBN Co network termination device (NTD) inside their home is already fitted with DOCSIS 3.1-capable technology."

Connections will also be made more reliable thanks to orthogonal frequency-division multiplexing (OFDM) modulation technology, NBN said.

"Although DOCSIS 3.1 does enable higher speeds on HFC networks, that is not our core focus at this present time," NBN CTO Ray Owen said.

"From an NBN Co point of view, DOCSIS 3.1 will help us increase capacity on the HFC network far more efficiently than conducting new optical node splits which will, in turn, free up construction resources elsewhere to complete the network build by 2020."

The HFC network is being upgraded by Arris -- which is also trialling full-duplex DOCSIS, which could enable 10Gbps symmetrical speeds -- after originally partnering with NBN back in 2015.

Outgoing NBN CEO Bill Morrow last year told ZDNet that DOCSIS 3.1 would see a "gradual rollout". With DOCSIS 3.1 NTDs already in the homes of those with NBN HFC connections, all NBN has to do is update the line cards in the cable modem termination systems (CMTS) and upgrade the software.

NBN had attained download speeds of 1Gbps and upload speeds of 100Mbps during a lab trial of DOCSIS 3.1 in June last year.

The HFC network should see around 100,000 premises released for sale every month through to April 2018, NBN added on Wednesday, after saying in May that there was still work to be done on remediating the HFC network.

"We now implement two new streams of work to optimise HFC connections on the NBN access network to ensure our equipment has been properly tuned to deliver the best possible service," NBN chief network engineering officer Peter Ryan said back in May.

"The first is what we call 'tap up', which includes everything on NBN Co's side of the network, from the pit in the street right through to the exchanges that connect to the wider internet.

"The other half of the optimisation work focuses on what we call 'tap down', which essentially follows the cables from the pit in your street and into your home where HFC services on the NBN access network are delivered."

In addition, NBN said it would be building more lead-ins and extensions across premises within the frozen footprint, so that homes and businesses can be connected faster once the HFC stop-sell ends in those areas.

NBN had relaunched sales on its HFC network in April after undertaking "considerable work" on the technology to ensure improvements across both stability and performance, with the work to continue during the staged release.

Both the federal government and NBN said the pause in selling HFC services would lead to improved migration and service experiences for customers.

Speaking to ZDNet, Ryan had said the company was "very happy with some of the earlier results we're seeing out of the areas that we have remediated" in the HFC footprint. At the same time, however, NBN also announced moving 440,000 HFC and fibre-to-the-node premises to its fibre-to-the-curb footprint.

NBN CFO Stephen Rue revealed during Q3 financial results in May that NBN spent AU$1 billion in capital expenditure on HFC in the last nine months due to "design, optimisation, construction activity".

As of March 31, NBN had 413,703 end users on HFC, with 1.4 million HFC premises ready for service and 443,681 HFC premises ready to connect.

Cost per premises (CPP) during the quarter to March 31 was AU$2,404 for HFC, with the network bringing in AU$85 million in revenue during the period.

"In relation to HFC ... despite the pause in activations, we have continued to build out this access network in addition to the remediation work being performed," Rue added.

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