Comcast preps DOCSIS 4.0 upgrade in Seattle

Comcast is preparing a DOCSIS 4.0 network upgrade in Seattle, Washington, where it competes with incumbent wireline providers such as Ziply Fiber and Lumen.

According to a post on DSL Reports, customers have been receiving messages notifying them that network upgrade activity is underway. That work will deliver faster upload speeds "in the coming days" and will later support multi-gigabit symmetrical speeds. The initial upload boost is likely coming from "mid-split" upgrades that dedicate more upstream spectrum.

A Comcast official confirmed that the messages alerted customers about work being done in the area and that it would lay the foundation for DOCSIS 4.0. However, the company is not saying when it expects to light up D4.0 services in the area.

But it does signal that Seattle is indeed in line for DOCSIS 4.0 upgrades that are already underway in a set of Comcast markets – Philadelphia, Atlanta and Colorado Springs, Colorado.

Comcast uses D4.0 as the basis of an X-Class Internet brand that currently delivers Internet speeds of up to 2 Gbit/s. Comcast also offers X-Class Internet tiers delivering symmetrical speeds of 300 Mbit/s, 500 Mbit/s and 1 Gbit/s.

Comcast has initially focused D4.0 network upgrades in areas where it has an "N+0" architecture where fiber is pulled deep enough to eliminate the need for amplifiers between the node and the home. For now, N+0 is necessary for Comcast to use the Full Duplex (FDX) option for DOCSIS 4.0 that enables upstream and downstream traffic to occupy the same block of spectrum. The other option, Extended Spectrum DOCSIS (ESD), operates downstream and upstream traffic in separate, dedicated spectrum.

Related:Cable ops are lab-testing 'enhanced' DOCSIS 3.1, CommScope says

The operator has been asked to confirm if its hybrid fiber/coax (HFC) plant in Seattle currently relies on an N+0 architecture.

CommScope is developing a new FDX amplifier for Comcast that will enable the cable operator to upgrade to D4.0 on HFC plant that operates multiple amps between the home and the node. A recent FDX amp lab trial delivered symmetrical speeds of 4 Gbit/s on a six-amplifier cascade – representative of the vast majority of Comcast's HFC network.

Once FDX amplifiers are commercially ready – perhaps later this year – it will put Comcast in position to accelerate and scale its DOCSIS 4.0 network upgrade program.

In the home, Comcast has been using a stand-alone modem and a separate Wi-Fi 6E access point to deliver DOCSIS 4.0 services. Comcast is nearing the launch of the XB10, a DOCSIS 4.0 gateway equipped with Wi-Fi 7.

Related:Fueled by network upgrades, cable outside plant spending to peak in 2027 – Dell'Oro

It's still not clear how widely DOCSIS 4.0 will be adopted by North American cable operators. Some operators, particularly small and mid-sized operators, are taking a closer look at how to squeeze more downstream performance out of their DOCSIS 3.1 networks using updated software for legacy, chassis-based cable modem termination systems (CMTSs) and new, upgraded D3.1 modems and DOCSIS 4.0 modems that can support additional orthogonal frequency-division multiplexing (OFDM) channels.

CommScope recently announced that operators have begun to lab-test that option – sometimes referred to as DOCSIS 3.1+ or DOCSIS 3.1 "enhanced" – using a new software release for its E6000 CMTS.