Dell'Oro Group analyst Jeff Heynen called it cable's "Unification Day."

As anticipated, Broadcom and a pair of its key cable operator partners declared Wednesday (September 25) that access to a new set of "unified" DOCSIS 4.0 chips for nodes, amplifiers and modems has become available to the full industry.

Those chips support both options for DOCSIS 4.0 – Full Duplex (FDX), which is being championed by Comcast, and Extended Spectrum DOCSIS (ESD), an option that is generally favored by other operators that are rolling out D4.0 or exploring DOCSIS 4.0 strategies. This unification move could tilt some of those operators toward the FDX option.

Previously, access to these new Broadcom chips was limited to a group of Tier-1 cable operators that had signed pricey joint development agreements (JDAs) with Broadcom. That group included Comcast, Charter Communications, Liberty Global and Cox Communications. Under those JDAs, cable tech vendors required help from the JDA operators to gain access to those chips. Cable operators that did not sign and pay for a JDA (along with their suppliers) had been temporarily shut out.

MaxLinear's new Puma 8 cable modem chipset supports only the ESD option for DOCSIS 4.0. However, MaxLinear doesn't currently make D4.0 chips for nodes and amplifiers – those, for now, remain the domain of Broadcom.

Execs with two JDA operators – Comcast and Charter – joined Broadcom at the stage at SCTE TechExpo in Atlanta on Wednesday to announce that all operators, both large and small, can now tap into a platform fueled by Broadcom silicon that paves the way for symmetrical multi-gigabit speeds, enhanced security and lower latencies delivered on widely deployed hybrid fiber/coax (HFC) networks. Broadcom's new unified silicon also embeds AI and machine learning engines designed to boost the performance and reliability of the HFC network.

Broadcom unified DOCSIS 4.0 chips for nodes, amps and CPE. (Source: Jeff Baumgartner/Light Reading)

The announcement arrives about a year after Comcast and Broadcom introduced a unified D4.0 chipset. Since that time, several operators outside the JDA expressed concern about how limits on access brought uncertainty to the DOCSIS market and their network roadmaps. That scenario caused some to consider upgrades to fiber-to-the-premises (FTTP) or to take a closer look at new, upgraded DOCSIS 3.1 products that can boost downstream speeds but aren't governed by joint development agreements.

Speaking Wednesday at TechExpo 2024 in Atlanta, Rich DiGeronimo, president of product and technology at Charter, said the move brings the cable industry together and unifies it around the DOCSIS 4.0 specification. It also reduces fragmentation and aims to drive "scaled economics" as cable operators look to improve their HFC with the "lowest cost to upgrade," he added.

Charlie Kawwas (far right), president of Broadcom's semiconductor solutions group, says the chipmaker has opened access to a new set of 'unified' DOCSIS 4.0 chipsets. He's joined by Charlie Herrin (center), president of Comcast's technology, product and experience organization; and Rich DiGeronimo, Charter's president of product and technology. (Source: Jeff Baumgartner/Light Reading)

Accounting for upstream splits

DiGeronimo, who was joined on stage by Comcast's Charlie Herrin and Broadcom's Charlie Kawwas, noted that Comcast has submitted its specs for a "mid-split" option for unified DOCSIS 4.0 and that Charter has contributed specs for the "high-split" option.
Both approaches dedicate more spectrum for the HFC upstream: mid-splits allow for a block of upstream spectrum in the range of 5MHz-85MHz and a high-split raises that range to 5MHz-204MHz.

The legacy low-split split for the North American cable industry is 5MHz-45MHz. Additionally, Full Duplex features an FDX band that allows upstream and downstream traffic to occupy the same block of spectrum.

Unleashing more interest in DOCSIS 4.0

The decision to open up access to the Broadcom unified chips is "great news" for certain cable operators in Europe as well as many Tier-2/3 US cable operators that previously did not have access, Hanno Narjus, the head of Teleste's global Networks business and CEO of Teleste Intercept, a US-based joint venture with Antronix, said here at the show.

The decision "should unleash more interest" among operators that were exploring DOCSIS 4.0 upgrades along with a 1.8GHz spectrum expansion, Narjus added.

Teleste, he said, has a committed roadmap for unified D4.0 silicon for distributed access architecture (DAA) nodes, but it has not yet established one for D4.0 amplifiers.

"We'll go where our customers go," he said. "But there's high confidence we can build it if there's interest in the customer base" for a unified D4.0 amplifier. CommScope, notably, has developed an FDX amp for Comcast's D4.0 architecture.

At the show, Harmonic demonstrated a full unified D4.0 system that featured its own "Pebble" remote PHY devices (RPDs) – one running FDX and the other running ESD – that were feeding an FDX D4.0 modem from Comcast and Broadcom and an ESD-based D4.0 modem from Ubee Interactive. All of those components were tied to cOS, Harmonic's virtual cable modem termination system (vCMTS).

"It [cOS] all runs off the same software," Asaf Matatyaou, Harmonic's senior vice president of product, said. He also believes that Broadcom's decision to open up access should encourage more operators to adopt DOCSIS 4.0.

But Broadcom's decision doesn't mean some modem makers will suddenly chase down a unified offering.

Hitron sticks with MaxLinear  

Hitron Americas has developed D4.0 and upgraded D3.1 CPE based on MaxLinear's ESD-only Puma 8 chipset and remains committed to that path.

Greg Fisher, president and CTO of Hitron Technologies America, believes there will be a sizable market for that offering. But he also believes that it helps the industry to have two sources for DOCSIS 4.0 silicon.

"We need these two chips in the ecosystem," he said. "More access is good for everybody."

To support interoperability at the node and other parts of the network, Hitron has been working with RPDs and vCMTSs from Harmonic and Vecima Networks.

Fisher said Hitron has commitments for DOCSIS 4.0 CPE as well as upgraded D3.1 devices that are sometimes referred to as DOCSIS 3.1+, DOCSIS 3.1 extended or "ultra" DOCSIS 3.1. He said 30% to 40% of conversations at this week's show were focused on the upgraded D3.1 option.