The Data-Over -Cable-Service-Interface-Specification version 3, more widely known as DOCSIS 3.0 or D3, is a cable industry standard for deploying broadband Internet service over HFC (Hybrid Fiber Coax) cable plant.  The standard is managed and updated by an MSO (Multi System Operator) supported consortium called CableLabs based in Colorado.  CableLabs defines the specification and certifies vendor products for interoperability.  D3 specifications define technologies such as channel bonding and IPv6 which allow MSOs to deploy 100Mbps+ Internet service and cable IPTV.  The products that must be D3 certified are CMTS (Cable Modem Termination System) at the operator premise and cable modem at the customer premise.

It has been more than three years since CableLabs issued the D3 specification in August 2006.  D3 has changed the playing field in broadband Internet services, giving life to the cable infrastructure once thought to be out-dated.  With D3 deployment well underway, cable has a defendable position against Telco FTTH/VDSL and potential for new advanced services.  Cable Operators worldwide are gaining more subscribers through D3, and vendors stand to benefit from this growth for many years to come.

D3 was borne out of the need to answer Telco’s VDSL2 and FFTH (ex:  Verizon FiOS).  Prior to the D3, the channelized nature of the cable spectrum limited broadband speed to 40Mbps.  Channel bonding in D3 allows MSOs to pump up speed in multiples of 40Mbps.  In theory, MSOs can get 80Mbps, 160Mbps, 320Mbps, and even reaching 1Gbps.  To deploy the service, MSOs need to either upgrade existing CMTS with new blades and software, or buy brand new D3 CMTS chassis.  On the customer premise side, there is no need to change cable modem if the subscriber does not want D3 service.  D3 CMTS is backwards compatible and supports older DOCSIS cable modems.

Deployment started even before CableLabs issued the specifications in 2006, and unlike previous Cable technologies, this one started overseas in places like Korea and Japan where the wire-line competition is fierce.  Today, D3 installations are covering a vast number of homes in North America, Europe, and Asia.   The tier 1 MSOs that have deployed D3 are Comcast (Cisco, Arris), TWC (Cisco, Arris, Moto), Liberty Global (Casa, Cisco, Motorola), Cox (Cisco, Motorola), Cablevision (Cisco), Virgin (Motorola), NumeriCable (Cisco), Ono (Cisco), and Rogers (Cisco).

Strangely, the D3 CMTS vendor community has shrunk over the years.  Since the inception of the D3 concept, vendors like Juniper, Terrayon, and BigBand have shut down their respective CMTS businesses.  The heavy engineering investment and the delay in D3 specifications made it difficult to maintain a reasonable P&L, particularly for vendors with a limited cable portfolio.  However, D3 deployment in the last two years has rejuvenated the industry, and today we have a community of three dominant players (Arris, Cisco, Motorola) and a startup (Casa Systems).  In the coming years, new CMTS vendors will surface from the QAM community with companies like Harmonics and RGB, and from the IP community with companies like ALU, Huawei, and Ericsson.  As D3 subscription picks up, cable modem vendors will see upside also, but this is unlikely to happen until 2011.  Today’s D3 subscription is less than 1% in companies such as Cablevision and Comcast.

In the coming years, MSOs will purchase even more D3 ports to beef up capacity for Cable IPTV.  Cable IPTV, or Video over DOCSIS, demands much more network capacity than the current data service which is mainly tuned for emailing and surfing.  MSOs will double or even quadruple the current DOCSIS capacity in order to deliver new service like “TV-Everywhere.”  Operators like Comcast are reportedly working on a new architecture whereby DOCSIS will be the primary delivery protocol in the HFC spectrum.  Today, QAM uses more than 90% of the cable spectrum to deliver TV channels to homes while DOCSIS varies from 5%-10%.

What is next after D3? PON has been in discussion but MSOs will likely focus on upstream bandwidth.  This is the Achilles Heel for Cable and even with D3 upstream channel bonding, it is limited to 120Mbps, while FTTH can get as high as 1Gbps.  This weakness will hurt cable in the growing enterprise subscribership.  Work is underway to look at how to re-design the 4Gbps cable spectrum to enable more speed on the upstream side.

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This entry was posted on Friday, October 30th, 2009 at 5:51 pm and is filed under Author, Rajan Varadarajan. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.