Comcast hits 4 Gbps in trial of DOCSIS 4.0 modem with Broadcom

Comcast continued its steady march toward DOCSIS 4.0, marking what it claimed was a first-of-its-kind trial of 10G modem technology.

Elad Nafshi, SVP of next generation access networks at Comcast Cable, hailed the test as a critical milestone, noting it shows it is possible to pass DOCSIS 4.0 signals end-to-end from the virtual cable modem termination system (vCMTS) through the node and on to the CPE. While a previous Comcast trial conducted in October was able to make the first end-to-end DOCSIS 4.0 link, Nafshi told Fierce that test used a modified DOCSIS 3.1 modem.

Its latest trial, however, used a prototype DOCSIS 4.0 modem built around Broadcom’s full duplex system-on-chip (SoC) and two cable modem chips. The modem was connected via a lab-based hybrid fiber-coaxial network to Comcast’s vCMTS operating in DOCSIS 4.0 mode.

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Comcast originally lab tested Broadcom’s chip in April 2021. In both the April and latest test, it achieved uplink and downlink speeds greater than 4 Gbps. Nafshi hinted there’s “a lot more to come” on the speed front, noting “we can go much, much faster.”

But for now, Nafshi said, the emphasis is on hardening and maturing the modem platform and getting Broadcom’s SoC into a production device. The operator is also continuing work developing a full duplex amplifier, which he said will help Comcast ensure it can deliver DOCSIS 4.0-enabled multi-gigabit speeds across its entire network.

“We’re taking power points and we’re making them real. This is no longer a concept,” he said. “With every day that goes by it becomes even more real…we’re week two of January and there’s a lot more to come later on in the year.”