NBN Co begins DOCSIS 3.1 rollout for HFC connections

NBN Co will progressively enable the DOCSIS 3.1 cable broadband standard across its hybrid fibre-coaxial (HFC) infrastructure, as it begins to ramp-up the number of premises connected to its access network using the technology.

NBN Co in 2015 first confirmed it planned to eventually enable DOCIS 3.1 for HFC connections, which doubles the downstream capacity available thanks to improved spectral efficiency and reduces the need to install additional optical nodes.

In addition the standard supports improved error correction compared to its predecessor as well as enhanced diagnostics.

The government-owned company had originally intended to begin the rollout of DOCSIS 3.1 in 2017. In June 2017 it revealed it had achieved gigabit downstream performance in lab trials and then in August last year NBN Co revealed it was preparing to conduct field trials using the technology.

When it was first announced, then communications minister Malcolm Turnbull said that download speeds of up to 1 gigabit per second and upload speeds of up to 100 megabits per second would be available for NBN Co’s HFC customers.

In theory the standard can support speeds of 10Gbps per second down and 1Gbps up. NBN Co has previously hinted at a potential move to Full Duplex DOCSIS 3.1, which could deliver 10/10Gbps.

Homes with existing NBN HFC services use DOCSIS 3.0; however, the NBN Co Network Termination Device (NTD) — the NBN box sitting inside a home — already supports the newer standard, with NBN Co saying most end users should have a immediate access to the upgrade once it is live in their service area.

In areas with active HFC services the upgrade requires the installation of new upstream line cards in NBN Co’s cable modem termination system (CMTS)

NBN Co expects to deploy DOCSIS 3.1 area by area, eventually covering almost all of its cable infrastructure by 2020.

NBN Co does not immediately expect to begin offering 100Mbps+ speeds across HFC; as of 31 March this year only a small number of NBN services with wholesale download speeds in excess of 100Mbps had been sold: 143 gigabit services, 14 500Mbps services and 294 250Mbps services.

“Although DOCSIS 3.1 does enable higher speeds on HFC networks that is not our core focus at this present time,” NBN Co’s CTO Ray Owen said in a statement.

“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.

“In addition, we also look forward to the benefits that DOCSIS 3.1 will help bring on the operational side of the network in delivering a more stable and resilient network for end-users.”

It has been a rocky road for NBN Co’s HFC rollout.

Shadow communications minister Michelle Rowland described the rollout of the technology as a “debacle”, pointing to the increased cost per premises of the technology since 2014.

After the Coalition’s victory at the 2013 election, NBN Co shifted away from a pure-fibre fixed line network to a ‘multi-technology mix’ (MTM).

Alongside renegotiation of its Definitive Agreements with Telstra covering the migration of customers to the NBN and, as part of the MTM, the transfer of portions of the copper network to NBN Co’s ownership, NBN Co also negotiated agreements with Telstra and Optus to take ownership of the telcos’ HFC networks.

However, in 2016 NBN Co revealed that it would scale back its plan to use Optus’ HFC assets — using the telco’s HFC infrastructure to connect only a single suburb. Instead, NBN Co announced, it would expand its planned rollout of fibre to the curb (FTTC, also known as fibre to the distribution point or FTTdp).

The biggest blow to the company’s HFC ambitions came in November last year, however, when it decided to pause sales of services based on the technology in the wake of significant user dissatisfaction with connection stability and performance issues.

It wasn’t until late April this year that the sale of HFC services resumed. At the same time as it ended the HFC pause, NBN Co revealed that 440,000 households would be added to the FTTC rollout — most of them homes that were originally slated to be connected with HFC but didn’t have lead-ins already installed.

NBN Co has taken a short-term financial hit from the pause; the full size of the impact will be revealed later this month when the company reports its full year results.