NBN HFC pilot delivers average download speeds of 84Mbps

Australia's National Broadband Network (NBN) company has completed its hybrid fibre-coaxial (HFC) trial, saying the network technology has been successful in delivering download speeds of up to 100Mbps and upload speeds of up to 40Mbps, with average speeds of 84Mbps down/33Mbps up.

The 4,500-premises HFC trial in Redcliffe, Queensland, was conducted from November until February, and saw retail service providers (RSPs) Telstra, iiNet, and Exetel deliver HFC services across the Optus HFC networking running DOCSIS 3.0 technology.

According to a report [PDF] undertaken by analyst firm Ovum, which was asked by NBN to review the pilot results, NBN's HFC service offers one of the fastest upload speeds in the world.

"NBN has been able to deliver these speeds through a redesign of the HFC network by utilising faster modulation rates and ensuring the number of premises at the node does not exceed their specifications," Ovum explained.

"NBN is confident its proposed HFC broadband speeds can be delivered across its HFC network moving forwards through a number of initiatives, including detailed network planning, node splitting, and a move to DOCSIS 3.1."

Ovum added that the average speeds were also lower than what would be attained in a real-world setting due to the tests running in parallel with the pilot and competing for bandwidth.

Node splitting, to decrease the number of premises sharing a fibre-optic node and therefore increasing bandwidth for those on the node, could also improve speeds in future, as could the implementation of DOCSIS 3.1 technology.

"The HFC pilot results are very encouraging as we look to ensure that our HFC end users are able to access the same speed tiers from their RSPs as our fibre-to-the-premise[s] (FttP) end users, with wholesale speed offerings up to 100Mbps downstream and 40Mbps upstream," NBN said.

"On our HFC pilot, we were using the current generation DOCSIS 3.0 technology, but from mid-2017, we plan to deploy next-generation DOCSIS 3.1 technology, which is capable of wholesale downstream speeds of 10Gbps and wholesale upload speeds of 1Gbps."

NBN added that with DOCSIS 3.1, HFC speeds should be "right up there" with the speeds attained across its FttP network, reaffirming that "existing network assets, whether they be HFC or copper networks, are capable of delivering great speeds to end users with new technological advances promising even greater speeds ahead".

Last week, NBN hailed new technology unveiled by worldwide HFC technology standards group CableLabs will facilitate DOCSIS 3.1 on HFC networks which would allow symmetrical multi-gigabit speeds for users.

Data Over Cable Service Interface Specification (DOCSIS) 3.1 supersedes the current DOCSIS 3.0 standard, allowing for faster speeds by freeing up around 50 percent capacity on the cable through more efficient transmission of data over the available spectrum.

"A newly unveiled project at CableLabs illustrates how DOCSIS 3.1 technology provides the basis for continued evolution of system capacities by supporting symmetric multi-gigabit service over the cable network," CableLabs vice president of Research and Development in Wireless Technologies Belal Hamzeh wrote.

In comparison to frequency-division duplex (FDD) and time-division duplex (TDD), full duplex DOCSIS sees both downstream and upstream traffic share the same spectrum. Symmetrical multi-gigabit broadband services are hence made possible through DOCSIS 3.1 technology when combined with full duplex DOCSIS.

Full duplex DOCSIS won't be launched for some time, however, with HFC spectrum bands to be opened up to 6GHz for this.

"Although it is still very early days, the arrival of Full Duplex DOCSIS 3.1 is extremely exciting news for NBN, and a real game-changing moment in the ultra-fast broadband market," NBN CTO Dennis Steiger said last week.

"We will be working closely with CableLabs to track the development of this technology, and are excited about the potential this offers for the 4 million premises that will receive their NBN services via our HFC network."

According to NBN, DOCSIS 3.1 will work across both Telstra and Optus' HFC networks, despite a leaked draft from NBN revealing in November that Optus' HFC network is "not fully fit for purpose", with 470,000 premises in the footprint needing to be overbuilt by either Telstra HFC or fibre services.

A Q&A on DOCSIS 3.1, published on the website of Australian Communications Minister cum Prime Minister Malcolm Turnbull a year ago said the technology would be coming to the NBN HFC network by 2017.

"We plan to run DOCSIS 3.1 trials in 2016, and we plan to have DOCSIS 3.1 services commercially available in 2017," Turnbull wrote.

"Bringing DOCSIS 3.1 on board is the cherry on the cake that will give us even more capacity and really make sure that there is plenty of bandwidth for everyone on the network to have a great experience."

According to reports, however, the highest throughput ever recorded using a single coherent receiver across a fibre network saw speeds of 1.125 Tbps.

The wide-scale rollout of NBN HFC was approved by the Australian Competition and Consumer Commission (ACCC) in June 2015, with a revised AU$11 billion deal allowing NBN to take ownership of Telstra's HFC and copper assets and Optus' HFC network.

The new deal came about as a result of NBN moving away from Labor's full FttP rollout following the Coalition's election at the end of 2013 to the present so-called multi-technology mix (MTM), which proposes to cover 20 percent of the population with FttP; 38 percent with fibre-to-the-node (FttN) and FttB; 34 percent with HFC; 5 percent with fixed wireless; and 3 percent with satellite services.

HFC will connect 4 million Australian premises in total, with 3.6 million of these coming from the old Telstra HFC network. The network will also be extended and infilled, with the Optus network likely to be infilled and overbuilt in the remaining 400,000 premises.

The HFC network will be launched in June this year, and completed along with the rest of the NBN by 2020.