The Road to DOCSIS 4.0

Jeff Baumgartner
The Bauminator
Jeff Baumgartner, Senior Editor, Light Reading
6/26/2019



It's been signaled for months, but CableLabs confirmed earlier this week that the Colorado-based R&D organization is moving ahead with DOCSIS 4.0, the next iteration of specs that has underpinned the cable industry's IP platform for widely deployed HFC networks.

Recent D3.1 annexes such as low-latency DOCSIS and Full Duplex DOCSIS will be organized under the 4.0 banner, as well as developing Extended Spectrum DOCSIS (ESD) techniques that will push capacity to 1.8GHz and super-charge the HFC network while also delaying the need to pull fiber all the way to the home. Future 3GHz ESD capabilities could put off full-scale FTTP upgrades for years to come.

The updated setup, "sets up a clear delineation on where DOCSIS 3.1 ends," Jeff Heynen, research director of broadband access and home networking at Dell'Oro, said. "It's smart to bundle these different, complementary technologies."

It also sets the path for Broadcom, Intel and other RF front end manufacturers to develop chips that build in these options for the development of this next-gen PHY layer and, ultimately, the updated MAC layer.

Heynen also views DOCSIS 4.0 is a representative step toward deep fiber, distributed access architectures and, for some MSOs, a move to node+0 architectures that eliminate the amplifiers between the home and the node.

Heynen notes that DOCSIS 4.0 (the specs could be done by mid-2019) doesn't change his forecasts looking out to 2023, as the updated specs should not alter the broader trends for more bandwidth, deeper fiber, and the move toward smaller and smaller service groups. "That's not going to change," he said.

What is going to change, or will need to change, is the management components that will be built into next-gen MACs. MSOs, he said, will need a lot more visibility and a deeper reach on managing their networks as they keep tabs on more software-driven devices at the edges that will be servicing these smaller and increased number of service groups.

That's a glimpse at what's ahead for cable's access network. Here's a snapshot of the road that got the industry to DOCSIS 4.0:

  • December 1996: Following the formation of what was initially called the Multimedia Cable Network System (MCNS), CableLabs and the industry introduced DOCSIS, an acronym for Data Over Cable Service Interface Specification for interoperable, multi-vendor network equipment and modems. Initially focused on single-channel data flows (6MHz channels for North American DOCSIS, and 8MHz-wide channels for EuroDOCSIS), Thomson (now Technicolor) and Toshiba were the first to nab D1.0 certifications for cable modems in March 1999, while Cisco Systems was first with a 1.0-qualified CMTS.

  • April 1999: CableLabs releases DOCSIS 1.1, an update that took the platform beyond "best-effort" with the addition of QoS and a path toward cable VoIP. More than two years passed before modems from Texas Instruments and Toshiba secured D1.1 certifications, and Arris and Cadant got 1.1 CMTS qualifications.

  • February 2000: Terayon Communication Systems got into some hot water for making claims that an erroneous spec called DOCSIS 1.2 would include the company's S-CDMA technology to help support upstream data in the lower regions of the cable spectrum. CableLabs smacked Terayon (sold to Motorola 2007) with a "cease and desist" letter on that count.

  • August 2001: CableLabs moves ahead with DOCSIS 2.0, a spec designed to bulk up the cable upstream by supporting both S-CDMA and TDMA. CableLabs completes the specs about five months later, and the first batch of D2.0 modems (from Motorola, Scientific-Atlanta, Terayon, TI and Xrosstech) achieve CableLabs certification in December 2002.

  • Summer 2004: CableLabs unveils plans for DOCSIS 3.0, adding support for IPv6 and channel bonding that will enable MSOs to offer downstream speeds in excess of 100 Mbit/s.

  • Summer 2006: CableLabs issues the D3.0 specs in the summer of 2006. The first D3.0 qualified CMTSs emerge in late 2007 under a three-tiered test program that let some vendors mass muster with gear that did not support upstream channel bonding out of the chute to help accelerate adoption of the new technology. A handful of D3.0-certified modems get the CableLabs stamp in May 2008. (See Go for the Bronze!.)

  • April 2008: Comcast launches D3.0-based services in the Twin Cities with a 50 Mbit/s downstream by 5 Mbit/s upstream service starting at a pricey $150 per month. (See Controlling Doc$is 3.0 and Comcast Enters the Wideband Era.)

  • October 2012: Execs with CableLabs, Cox, Time Warner Cable and Comcast introduce details about DOCSIS 3.1 at Cable-Tec Expo in Orlando, Fla. The central theme is boosting bandwidth efficiency by about 50% using blocks of OFDM subcarriers, a pivot away from QAM channels, and the pursuit of 1-Gig services. However, the first D3.1 modems are hybrids that can support both DOCSIS 3.0 and D3.1-based traffic. CableLabs issues the first-generation of DOCSIS 3.1 specs in the fall of 2013.

  • February 2016: Comcast announced a handful of launch cities for its first D3.1-based services, and completes its network rollout by the fall of 2018. Charter completes its D3.1 network rollout in most markets by the end of 2018. The year before, CableLabs publishes the PHY layer specs for Full Duplex DOCSIS, an annex to D3.1 that guns for multi-gigabit symmetric services.

    — Jeff Baumgartner, Senior Editor, Light Reading

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