Cable Operators Take a Giant Leap Toward DOCSIS 3.1

Gearing up for the rapidly emerging Gigabit era, cable operators are pinning most of their hopes on DOCSIS 3.1, a next-generation broadband tech specification. Comcast recently announced it would conduct market trials of the new spec this fall. The giant MSO then aims to roll out the Gigabit-enabling technology to markets throughout the nation over the next couple of years. 

Comcast joins other major cable providers such as Liberty Global in Europe, Videotron in Canada, NBN in Australia and Cox Communications and Suddenlink Communications in the U.S. in making a firm commitment to DOCSIS 3.1. And, with growing competitive pressure from fiber-based providers deploying Gigabit services, many other cable operators across the globe are chomping at the bit to deploy it as well.

In fact, a recent IHS survey found that, on average, cable providers expect to pass about a third of their residential broadband subscribers with DOCSIS 3.1-enabled headends by April 2017. In the U.S. alone, that would translate to more than 17 million cable modem homes passed by DOCSIS 3.1 in less than two years.

Assuming this projected rollout pace is achieved, DOCSIS 3.1 will end up far more widely deployed in the early going than its predecessor, DOCSIS 3.0, as well as earlier versions of the cable broadband spec. In contrast, many cable operators have still not upgraded all their systems for DOCSIS 3.0, more than nine years after CableLabs completed the spec and more than seven years after the first MSO rollouts began.

Achieving Gigabit Speeds
It's easy to see why enthusiasm for DOCSIS 3.1 is running so high. The latest version of the industry's enduring DOCSIS standard is designed to support data downstream speeds as high as 10 Gbps and upstream speeds of at least 1 Gbps. While the current industry flagship spec, DOCSIS 3.0, can enable downstream speed bursts as high as 1.2 Gbps through advanced channel-bonding, it tops out at that level in North America and doesn't come close to supporting upstream Gigabit speeds.

What makes DOCSIS 3.1 so fast? For one thing, the new spec leverages a technology called orthogonal frequency division multiplexing (OFDM) to move more data across cable's hybrid fiber-coaxial (HFC) networks. Breaking free of the cable industry's current reliance on 6MHz and 8MHz channels, OFDM subcarriers allow operators to use far more spectrum for channel-bonding, enabling them to boost transport speeds.

For another, DOCSIS 3.1 allows cable operators to tap into much higher QAM modulation orders than its predecessors, along with a new forward error correction technique called low-density parity-check (LDPC). As a result, operators will be able to use their existing spectrum far more efficiently than before, essentially squeezing much more juice out of the same orange.

Another key attribute of DOCSIS 3.1 is that it's backwards compatible with DOCSIS 3.0 and doesn't require extensive plant upgrades, meaning cable operators will be able to deploy DOCSIS 3.1 equipment on their existing networks incrementally, upgrading their systems market by market, neighborhood by neighborhood or even fiber node by fiber node.

With cable vendors now scrambling to develop and deploy cable modems, gateways, set-top boxes, cable modem termination systems and other equipment for DOCSIS 3.1, CableLabs has already begun intensive interoperability ‘plugfests’ of DOCSIS 3.1 gear. The cable organization is expected to begin certifying the first equipment for MSO use this fall, enabling the expected broad industry rollout to begin.

Of course, the new spec faces some critical challenges. In the short term, they include the development of new installation and maintenance tools and massive re-training of cable engineers and technical operations staff. But, with the Gigabit era now here, cable operators insist that they won't let these challenges stand in their way.

Photo by Imelda with Creative Commons license