The Passband Bi-directional PHY on coax and the Passband Unidirectional PHY on coax may be used together on the same physical medium.
Spectrum allocation for the integrated unidirectional & bi-directional
passband PHY on a single coax
The DOCSIS® Set-top Gateway (DSG) specification defines an interface and associated protocol that introduces additional requirements on a DOCSIS® CMTS and DOCSIS® CM to support the configuration and transport of a class of service known as "Out-Of-Band (OOB) messaging" between a Set-top Controller (or application servers) and the customer premise equipment (CPE). In general, the CPE is intended to be a digital Set-top Device, but may include other CPE devices, such as Residential Gateways or other electronic equipment. Figure 1–1 provides the context for this specification in relation to the data-over-cable reference architecture and the other interface specifications in the family. Traditionally, the physical transport of this Out-Of-Band messaging has been carried over dedicated channels, as specified by [SCTE 55-1] and [SCTE 55-2]. This specification defines the applicable communications standards and protocols needed to implement an Out-Of-Band messaging interface to the Set-top Device using DOCSIS® as a transport. It applies to cable systems employing HFC and coaxial architectures. Specifically, the scope of this specification is to:
• Describe the communications protocols and standards to be employed.
• Specify the data communication requirements and parameters that will be common to all units.
Open Optical Interface; a point at which an optical signal is passed from one equipment medium to another without conversion to an electrical signal. [Fib111]
An amplifier’s 1 dB output compression point in dBm, and defined as the output level that is 1 dB lower than it should be for a corresponding input level in linear operation. The output and input 1 dB compression points are related by OP1dB = IP1dB + Gain – 1. See Mathematical Definitions and Derivations for more information.[Ard11]
Open Systems Interconnection (OSI)
A framework of the International Organization for Standardization (ISO) standards for communication between different systems made by different vendors, in which the communications process is organized into seven different categories that are placed in a layered sequence based on their relationship to the user. Each layer uses the layer immediately below it and provides a service to the layer above. Layers 7 through 4 deal with end-to-end communication between the message source and destination, and layers 3 through 1 deal with network functions.
OpenCable is an initiative led by CableLabs on behalf of its members, seeking to set a common set of requirements for interoperable digital set-top boxes, television receivers and other advanced digital devices manufactured by multiple vendors. These devices would be capable of delivering digital video, data and interactive services to a television set. See also CableCARD™, OCAP™.
OpenCable™ Application Platform (OCAP™)
The OpenCable Application Platform is a software interface specification that completely defines the OpenCable host software interface that executes OpenCable portable, interactive applications and services. OCAP is a separate effort from the Advanced Television Enhancement Forum (ATVEF) content specification, but OCAP does call for support and extension of ATVEF as a part of the PE requirements.
An OpenCable device is an OpenCable-compliant digital set-top converter or cable ready digital television receiver, allowing reception of existing cable television channels and providing the user interface for future, interactive applications.
OpenCable™ Unidirectional Receiver (OCUR)
This is a device that uses a CableCARD™ to get conditional access protected broadcast digital content from a cable television provider, protect it with a CableLabs approved digital rights management (DRM) system, and send it out over the digital rights interface (DRI) to a home media server (HMS). Currently, the only approved digital rights management (DRM) is Windows Media DRM (WMDRM). The only HMS approved so far is the Microsoft Media Center Edition (MCE) running on a Microsoft Vista operating system. Authorized use of OpenCable™ unidirectional receiver (OCUR) and any associated DRM systems are controlled by CableCARD host interface licensing agreement (CHILA).
Open Systems Interconnection (OSI)