Comcast hits 4 Gbps in trial of full duplex SoC

Comcast 10G
A Comcast Cable exec told Fierce the test marked “the first time, period, that DOCSIS 4.0 has transitioned from being a spec to being real.” (Comcast)

Comcast notched another milestone on the road to 10G, achieving symmetrical speeds of more than 4 Gbps in a trial of a new Full Duplex DOCSIS 4.0 system-on-chip (SoC) from Broadcom.

Elad Nafshi, SVP of next generation access networks at Comcast Cable, told Fierce the test marked “the first time, period, that DOCSIS 4.0 has transitioned from being a spec to being real.”

Unveiled by CableLabs in March 2020, the DOCSIS 4.0 standard was designed to enable operators to drastically increase performance on their networks, achieving 10 Gbps downstream and up to 6 Gbps upstream. That factors out to twice the downlink speed and quadruple the uplink speed possible using DOCSIS 3.1.

Comcast noted that Broadcom’s SoC is expected to become the first production silicon to use the DOCSIS 4.0 Full Duplex Standard.

Nafshi said the trial used the Broadcom SoC in a simulated hybrid fiber-coaxial (HFC) network environment, rather than on a live plant, running video and data traffic over up to 1.2 GHz of spectrum to achieve upstream and downstream speeds of more than 4 Gbps. But he noted it expects to be able to wring out even more speed with additional optimizations, for instance by applying its Octave artificial intelligence platform to a DOCSIS 4.0 setup.

RELATED: CableLabs sticks a fork into DOCSIS 4.0 specification

Last year, Comcast deployed Octave to modulate traffic on its existing network and significantly boost capacity during the Covid-19 pandemic. “Imagine we do that now on multiple gigabits worth of capacity and what we should be able to do leveraging the platforms that we already have in place,” Nafshi said, adding “the term 10G is not there for marketing purposes, that’s our ultimate goal.”

As in wireless networks, Nafshi said the downstream channel has traditionally been dominant in its network, carrying 14 bits for every bit headed upstream. He added the push to offer enhanced symmetrical capabilities will open the door to new and improved customer experiences, "whether it's AR or VR, whether it's additional communications services that will start to emerge. Who knows what the post-Covid world will look like."

Comcast Cable President of Technology, Product and Experience Charlie Herrin noted in a statement the trial milestone was “particularly exciting, because this technology is an important step forward toward unlocking multi-gigabit upload and download speeds for hundreds of millions of people worldwide, not just a select few.”

RELATED: Comcast’s peak upstream traffic increased 56% in 2020

Nafshi concluded “this is really a massive technical milestone, but it’s really only a first…now the work is on maturing it, hardening it and getting ready to put it out to consumers.”

Comcast previously achieved symmetrical speeds of 1.25 Gbps in a trial conducted in October, which used a cloud-based virtual cable modem termination system (vCMTS), distributed access architecture (DAA) technology and remote PHY nodes.