CableCARD - Technical Overview

Technical Overview

CableCARD is a term trademarked by CableLabs for the Point of Deployment (POD) module defined by standards including SCTE 28, SCTE 41, CEA-679 and others. The CableCARD is physically a PCMCIA type II PC card, supplied by the cable company, which is inserted into a slot in the host (typically a digital television set or a set-top box) in order to identify and authorize the customer, and to provide proprietary decoding of the encrypted digital cable signal without the need for a set-top box. The cable tuner and QAM demodulator themselves are part of the host device, as is the MPEG decoder. The role of the card is to perform any conditional access and decryption functions. This results in an MPEG-2 transport stream, which is decoded by the host. The card also receives messages sent over the out-of-band signaling channel by the cable company's Head end servers and forwards them to the host.

Cards from major providers such as Comcast, Cox Communications, RCN and Time Warner Cable in some regions currently require on-site installation by a technician, who reports the unique ID numbers pre-assigned to both the CableCARD and the digital television to the company headquarters, where they are updated to the customer's account. Because of this, CableCARDs cannot be moved from one device to another without a visit from a cable company installer. Some regions (such as Comcast Houston) do allow customer installs, and actually provide special phone support for CableCARDs. The card is inserted as users do for laptop PCMCIA cards. The CableCARD identification numbers are given to the operator who then sends the CableCARD an out of band Entitlement Management Message (EMM), which remotely programs the CableCARD, authorizing it to decode for the specific host only those shows and services which the user is authorized to view.

CableCARDs with personal computers:

Existing integrated cable set-top boxes perform four basic functions:

1. Enable receiving and selecting digital and analog cable channels
2. Uniquely identify the customer and authorize the features to which they have subscribed
3. Decode scrambled digital channels and premium programming such as movie channels
4. Provide interactive two-way communications for:
   1. Interactive programming guides
   2. Pay-per-view
   3. Video on Demand
   4. Switched video streams

New digital televisions and other devices that are labeled DCR (Digital cable ready) contain:

• built-in support for receiving digital cable channels (via an internal QAM tuner)
• a slot for the current version of CableCARD (see photo here), which allows decryption of encrypted digital channels.

The CableCARD 2.0 specification includes support for #1-4, interactive two-way communications; however it is unknown exactly when CableCARD 2.0 hosts and compatible servers will become available. Future devices which support CableCARD 2.0 are expected to be labeled iDCR "Interactive digital cable ready". Among other requirements, CableCARD 2.0 hosts will be required to provide the OpenCable Application Platform (OCAP), also known as Tru2Way, to run programs downloaded from the cable company.

An alternative to CableCARD 2.0, most recently advocated by the U.S. cable television industry, uses Downloadable Conditional Access System (DCAS) in place of physical CableCARDs. In this proposal, a custom security chip must be soldered into every compliant host; if a security scheme is compromised, a new security program can be downloaded to the host device.

Because the conditional access system is in software, it can be sent with the video as a form of Digital Rights Management (DRM). The CableCARD Host Licensing Agreement (CHILA) and the DCAS agreement restrict the technologies that CE companies may use for distributing video from host devices. CE companies object to this expanding the notion of CableCARD network security issues to also include content protection issues. They prefer to deal with content owners directly with their standards and regard cable company protocols and formats as a transport only. CE companies wish to communicate video inside the home network using their own protected protocols and formats.

The OpenCable Application Platform (OCAP) is a Java-based platform intended for use either with any security access scheme — whether it is CableCARD 2.0 devices or future downloadable security schemes. OCAP was tied to CableCARDs because, as it was imagined by CableLabs, the additional processing necessary for managing the communication with the cable company server would be performed, not on the cable company provided equipment (the CableCARD), but on the consumer electronics device — known as the CableCARD "Host". CE companies objected that OCAP is unnecessary for the simple task of managing two-way communications on the cable networks. The CEA perspective is that Java is not efficient for CE devices, and that cable companies are passing to CE manufacturers the costs of a software platform which they didn't need, and which won't run on their existing hardware architectures.

The consumer electronics industry proposed in November 2006 that the CableCARD 2.0 specification be upgraded to include the provision for modified MCards that would support the communications necessary for VOD, PPV, and Switched Video. This card would be backward compatible with older cards, and support would be required for them on cable company servers by January 2008. These modified MCards would not allow two-way communication using current OCURs, which, by definition, are unidirectional. This so-called "OCAP-less" proposal was rejected by the NCTA for a variety of reasons elaborated on in the issues segment of this article. The technical advantage is that much less is assumed about the computing capability of the host, allowing the manufacturing cost to be significantly reduced. The disadvantage is that the MCard will be slightly more expensive, but the host will not necessarily be able to support the envisioned ecommerce and banking applications. CE companies argue that such a card fulfills the 1996 law's requirement that cable companies allow two-way communication on their networks, and that OCAP fulfills technical goals far in excess of those necessary for such two-way communications.