NBN chief technology officer Dennis Steiger has hailed as a “game-changing moment” an announcement from CableLabs that it has proved the viability of full duplex communication over hybrid fibre-coaxial (HFC) connections using the DOCSIS 3.1 standard.
CableLabs is a US-based R&D consortium responsible for developing cable broadband standards.
“Existing technologies mostly use either Frequency Division Duplexing (FDD) or Time Division Duplexing (TDD),” CableLabs said in its announcement.
With FDD upstream and downstream data is transmitted over different frequencies, while TDD involves upstream and downstream traffic taking turns over the same spectrum.
Full Duplex involves both upstream and downstream traffic employing the same spectrum at the same time, CableLabs said.
“A DOCSIS 3.1 Full Duplex network provides the peak speeds and flexibility of TDD solutions, but one-ups both TDD and FDD with double the capacity,” the announcement by CableLabs’ Belal Hamzeh and Dan Rice said.
The two wrote that the approach employed by CableLabs in its tests could deliver symmetric multi-gigabit broadband data services.
“These developments are expected to yield DOCSIS 3.1 network performance of up to 10 [gigabits per second (Gbps)] symmetrical on 1 GHz HFC networks, with the potential for even higher performance by utilizing spectrum that is currently available for future expansion above 1 GHz,” the announcement said.
“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,” Steiger said in a statement released by NBN.
Steiger was in the US meeting with CableLabs.
NBN previously indicated that it expected upgrading the Optus and Telstra HFC networks to DOCSIS 3.1 could deliver speeds of up to 1000/100Mbps to end users.
The company’s corporate plan earmarks some 4 million premises for connection via HFC, equating to some 34 per cent of the total number of premises that will be connected to the National Broadband Network (most premises in the fixed-line footprint will be connected by fibre to the node or fibre to the basement).
NBN launched an HFC pilot in November last year. The commercial launch of its HFC product is due in calendar Q2 this year.
An NBN document leaked last year revealed the limitations of the Optus HFC infrastructure, including oversubscribed nodes, problems with noise and equipment that was nearing end of life. That document suggested that the Optus HFC network could be overbuilt.
In a Senate Estimates hearing earlier this month, NBN executives were probed on the document and their HFC plans.
NBN CEO Bill Morrow said that the company still intended to employ the Optus HFC network infrastructure, but the number of premises it would be used to connect was still being evaluated.
“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,” Steiger said today.
“Previously it was only possible to deliver multi-gigabit symmetrical broadband if you deployed an FTTP network – but HFC is now right up there in terms of being able to deliver these kinds of speeds.
“We now have the pathway to deliver these ultra-fast symmetrical speeds to our HFC end-users both very cost effectively and far more conveniently than we could if we had to deliver fibre all the way to their homes.”
The standardisation process for Full Duplex DOCSIS 3.1 is expected to commence mid-year.