CableLabs Publishes DOCSIS 4.0 Specs

Details on next-gen standard arrive as DOCSIS 3.1 handles strains of COVID-19
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CableLabs has published the anticipated specifications for DOCSIS 4.0, the next technology standard for moving data across the cable industry’s hybrid fiber coaxial (HFC) networks.

The new specifications, an upgrade over the industry’s current DOCSIS 3.1 standard, will enable cable systems to deliver download speeds of up to 10 gigabits per second. Upstream speeds can approach speeds of 6 Gbps.

Comcast's Tony Werner told reporters the MSO has been up to the task of handling the coronavirus-forced surge in web traffic. 

Comcast's Tony Werner told reporters the MSO has been up to the task of handling the coronavirus-forced surge in web traffic. 

Importantly, DOCSIS 4.0 unifies two competing technologies for moving HFC networks to 10-gig speeds. Full Duplex DOCSIS (FDX) would combine downstream and upstream signals on a single frequency, delivering symmetrical speeds up to 10 Gbps. FDX is favored by Comcast, but its stringent network technology requirements made it economically infeasible for many operators.

Extended Spectrum DOCSIS keeps upstream and downstream traffic separate. But it would increase the spectrum of HFC networks to 1.8 GHz from a current level of 1.2 GHz found on the fastest networks.

Working Towards 10G

CableLabs is the technology consortium for the major U.S. cable companies. And it’s serving a broader cable industry initiative called “10G,” an effort to migrate cable networks to a future in which 10 Gbps speeds power increased cloud applications, video conferencing, smart homes and distance learning — a future that is, well, here today for many of us.

DOCSIS 4.0 gives cable industry engineers in purchasing roles clarity on how to move forward in a network technology realm being disrupted by virtualization and Distributed Access Architecture (DAA).

“With the DOCSIS 4.0 specification establishing a clear path forward, giving cable operators the flexibility to pursue either Extended Spectrum DOCSIS (ESD) or Full Duplex DOCSIS (FDX), operators can move ahead with their remote PHY and remote MAC-PHY deployments to solve immediate headend and power consumption issues,” Dell’Oro Group analyst Jeff Heynen wrote in a March blog post.

But don’t look for commercial deployments of DOCSIS 4.0 networks by operators in the months to come. Cable operators still have a glut of network capacity from huge investments made over the last five years in DOCSIS 3.1 infrastructure. These buildups enabled them to offer customers 1 Gbps speeds, the ceiling for which consumers are nowhere near bumping into just yet.

Cable's Net Holds Fast

And the networks are holding up well to current capacity strains wrought by homebound social distancing. Comcast’s top technologist, president of technology and product Tony Werner, said the No. 1 cable company’s networks are holding up just fine in locations like San Francisco and Seattle, which have seen traffic increases as high as 60% in peak weekend usage hours recently.

“Usage is on the rise as more people are working, learning and doing all their entertaining at home,” Werner said on a March 30 call with reporters. “But it’s all within the capability of the network.”

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