Comcast has deployed DOCSIS 4.0 in parts of ten markets spanning more than 1 million homes. The pace is expected to pick up as Comcast starts to deploy a new amplifier that enables the operator to deploy D4.0 across the vast majority of its footprint of 63 million residential and business locations.

Following initial rollouts in Atlanta, Philadelphia and Colorado Springs in which the core technology has been optimized and hardened, Comcast has since initiated D4.0 deployments in Sacramento, Denver, Seattle, Augusta, Miami and Pittsburgh, an official tells Light Reading.

During a Tuesday keynote at this week's SCTE TechExpo in Atlanta, Elad Nafshi, Comcast EVP and chief network officer, said the operator has deployed about 160,000 distributed access architecture (DAA) nodes that play a critical role in the D4.0 deployment. That's up from the 140,000 the company reported in March.

"We're at mass scale," he said.

Symmetrical 3-Gig and 5-Gig on Comcast's D4.0 roadmap

Comcast is initially using D4.0 to deliver symmetrical speeds up to 2 Gbit/s under the "X-Class" brand.

"That's the starting point for us," Rob Howald, VP for network architecture and a fellow at Comcast, said on a Tuesday panel focused on Comcast's deployment of Full Duplex (FDX) technology.

Comcast has put plans in motion to deliver symmetrical speeds of 3 Gbit/s in 2025 and 5 Gbit/s in 2026 via the new D4.0 network, Howald said. But he stressed that business decisions will drive when and if Comcast introduces those speeds and that it's the job of the engineers to get those capabilities in place.

Nafshi said Comcast is now ready to accelerate the deployment of DOCSIS 4.0 as it integrates "unified" chipsets from Broadcom for nodes, amplifiers and modems that support both FDX and Extended Spectrum DOCSIS (ESD). Those unified chips will also put Comcast in position to upgrade its HFC plant to 1.8GHz. A collaboration between Broadcom, Charter and Comcast envisions an upgrade to 3GHz spectrum and a possible path to what could become DOCSIS 5.0.

Growing role for AI and ML

Introduced by Broadcom and Comcast last year, the new chips also embed artificial intelligence (AI) and machine learning (ML) engines that can pinpoint network issues and, in some cases, fix them before the customer becomes aware there's a problem.

Rather than analyzing "red blobs" on the network where impairments might be present, "we're now able to detect patterns on a network within feet away from the customer," Nafshi said.

FDX amps ready for their close-up

A critical addition is an FDX amplifier that allows Comcast to deploy D4.0 across the vast majority of its hybrid fiber/coax (HFC) network, not just in areas where it has pulled fiber deep enough to eliminate all of the amps that reside between the node and the home (also known as N+0). The FDX amp puts Comcast in position to deploy D4.0 to a much broader portion of the network that utilizes a cascade of amps.

Some earlier tests conducted by Comcast focused on a six-amplifier cascade (N+6), but it's become clear that it will also work beyond that, including N+8 architectures, Marc Morrissette, senior principal engineer, access networks, Comcast, said at the operator's FDX panel here.

The operator announced this week that its first live deployment of an FDX amp from CommScope recently took place in Comcast's northeast division.

That initial rollout will exercise the FDX amp hardware and software. The plan is then to extend the deployment of FDX amps across Comcast's footprint as FDX amps begin to reach volume production toward the end of 2024 and into 2025, Morrissette said.

CommScope's Starline Full Duplex (FDX) amplifier. (Source: CommScope)

Comcast is also deploying FDX nodes from CommScope and Harmonic.

Update: A likely second source to Comcast for FDX amps is Sercomm. Sercomm, a maker of the Xumo streaming box for the Comcast-Charter streaming joint venture, introduced an FDX amp powered by Broadcom's unified D4.0 silicon at this week's TechExpo. Comcast declined to comment when asked if the operator has tagged Sercomm to supply FDX amps for the operator's D4.0 rollout.

DOCSIS 4.0 CPE advancements and 'FDX-L'

Comcast says it's also making some advancements on D4.0 customer premises equipment (CPE).

Comcast initially launched D4.0 using a two-box combo that paired a standalone cable modem with a standalone Wi-Fi router. The operator is now starting to deploy D4.0 gateways that combine those elements plus additional IoT capabilities. Speaking at a Light Reading-hosted session on Tuesday morning, Howald said Comcast has begun initial field trials of the XB10, an FDX-only DOCSIS 4.0 gateway equipped with Wi-Fi 7.

Comcast, he added, is also working on a new model, the XB10u, that will be powered by Broadcom's new unified FDX/ESD D4.0 chipset.

"We've always talked about [FDX and ESD] as complementary technologies, because they are complementary technologies. This is the first solution that allows you to take advantage of that," Howald said.

Howald said Comcast is also developing software for DOCSIS 3.1 modems that will enable what the operator calls "FDX-L" – with the "L" standing for "limited." That designation is for updated software for DOCSIS 3.1 modems that will enable the devices to use the downstream orthogonal frequency division multiplexing (OFDM) channels present in the bi-directional FDX band. Howald said the move allows DOCSIS 3.1 devices to use downstream spectrum in the FDX band and enables Comcast to make more efficient use of its HFC spectrum.

Self-install DOCSIS 4.0 on the way

Comcast currently uses pro installs for DOCSIS 4.0. The shift to the unified chips will pave the way for a new self-install option that will be similar to Comcast's self-install program for DOCSIS 3.1 modems and gateways.

Another key element of Comcast's new access network is a virtual cable modem termination system (vCMTS) based on Harmonic's cOS platform that runs on commercial off-the-shelf servers (COTS). Comcast expects to launch fourth-generation hardware for its vCMTS early next year.

Nafshi estimated that the platform allows Comcast to automate 99.75% of its software functions. Comcast, he added, has implemented some 300,000 software changes to the platform year-to-date.

Rogers adopts Comcast's network design

Comcast's approach to HFC and DOCSIS upgrades has also become the roadmap for Rogers Communications, Canada's largest cable operator.

Rogers announced this week that it will adopt Comcast's network design, including its distributed access architecture (DAA) and tools along with the unified DOCSIS 4.0 platform.

Rogers said it intends to use that design across its footprint. The operator has been trialing DOCSIS 4.0 with a small group of customers in Calgary that's initially delivering speeds of 4 Gbit/s down by 1 Gbit/s upstream.

Rogers has been asked if it intends to pursue FDX as part of its DOCSIS 4.0 rollout.

Rogers said in the announcement that the move gives it a "clear path to roll out next-generation" unified DOCSIS 4.0 technology.

The companies said Comcast Technology Solutions will provide Rogers with its new access network solution as part of the new agreement. It's a clear indication that Comcast is now pushing forward with a plan to effectively syndicate its D4.0 platform as it does with other platforms, including X1.

The new network design agreement is the latest tech-focused partnership between the two operators.

Rogers' current video platform is based on an X1 syndication deal with Comcast. Earlier this year, Rogers cut a new ten-year deal that includes Comcast's latest wave of video streaming devices, broadband gateways and home security products.