Comcast, Cox are bringing DOCSIS 4.0 to life in their labs

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Robert Howald, a fellow in Comcast’s Next Gen Access Network organization, said its lab team is working to build the first end-to-end full duplex DOCSIS (FDX) link. (Comcast)

Comcast and Cox Communications are chugging along down the road toward DOCSIS 4.0, aiming to take work currently being done in the lab out into the wild in the near future.

Executives from both companies shed light on their progress during a pre-conference session held before the official start of SCTE’s Cable-Tec Expo on Tuesday. During a panel discussion, Guy McCormick, Cox’s SVP of engineering, said impending competition from fiber overbuilders is motivating many cable players to “accelerate some of our initiatives toward multi-gig and multi-gig symmetrical services.”

In Cox’s case, he said the operator has already deployed distributed access architecture (DAA) and Remote PHY devices (RPDs) across 30% or more of its network and is working to acclimate its operations teams to working in a multi-platform environment as it deploys these new technologies alongside traditional HFC and analog nodes. The company currently has sub- and mid-split implementations but is planning to move to a high-split “soon,” he said.

In a later panel, Cox chief access scientist Jeff Finkelstein said it was initially targeting a 492 MHz high-split to provide around 10 Gbps downstream and around 5 Gbps up. However, he added it is now also seriously considering a 396 MHz high-split (offering around 10 Gbps down and 3 Gbps up) to leave room for future upstream growth.

McCormick also noted Cox is “just now getting our hands on some of the prototype SOCs and kicking those things around in the lab.”

Comcast is also hard at work in the lab. Robert Howald, a fellow in Comcast’s Next Gen Access Network organization, said it is currently focused on integration work, testing remote PHY devices (RPDs) and chips for customer premises equipment. 

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He added Comcast’s virtual cable modem termination system “actually speaks DOCSIS 4.0 now,” and said the operator’s lab team is working to build the first end-to-end full duplex DOCSIS (FDX) link. “That’d be a pretty awesome thing to have achieved and that’s where we plan to get to this year,” Howald stated.

Integration projects are expected to continue into 2022, when Comcast expects to introduce FDX amplifiers into the lab environment. From there it will look to take things “out of our lab environments into real environments, seeing what it looks like out in those kind of environments and getting our technical operations folks familiar with DOCSIS 4.0 at that time,” Howald said.

Comcast previously outlined plans to move to a mid-split on its way to DOCSIS 4.0. Howald noted “As we look ahead to the migration of the plant to put in amplifiers that support mid-split, we are looking at developing that FDX amplifier in such a way that we preposition amplifiers to be able to take an FDX upgrade later to make that more efficient when the time comes to start upgrading to DOCSIS 4.0.”