DOCSIS 4.0

What It Means

DOCSIS 4.0 is the cable industry's response to the FTTH threat, an upgrade to the DOCSIS specification published by CableLabs in March 2020 that pushes maximum downstream capacity to 10 Gbps and upstream to 6 Gbps over existing coaxial cable. Two distinct approaches compete under the DOCSIS 4.0 umbrella: Full Duplex DOCSIS (FDX), favored by Comcast, allows simultaneous upstream and downstream transmission on the same frequencies, and Extended Spectrum DOCSIS (ESD), favored by Charter and Cox, expands the usable frequency range up to 1.8 GHz to create new upstream capacity. Both approaches deliver symmetrical multi-gigabit service, matching the core performance promise of fiber-to-the-home. Comcast launched its first DOCSIS 4.0 markets in Colorado Springs, Atlanta, and Philadelphia in late 2023 and plans to cover more than 50 million passings by the end of 2026. The strategic advantage of DOCSIS 4.0 is capital efficiency: upgrading existing hybrid fiber-coax plant to DOCSIS 4.0 costs roughly $100 to $200 per home passed, versus $500 to $2,000 per home passed for fiber overbuild. This 5 to 10x cost advantage is why cable operators can continue to defend their roughly 55% market share even as fiber deployment accelerates. For the Broadband Grade, DOCSIS 4.0 availability counts fully toward the download speed score (40% of grade) but does not count as fiber availability (20% of grade).

Frequently Asked Questions