By Jorge Salinger & Steve Sigman, Comcast Cable Communications
Cable operators have been actively converging video and data services into a common Converged Cable Access Platform (CCAP) platform for a few years now. This trend, which requires an evolution towards newer, more modern, and denser equipment, should free up space in the headend.
However, as the success of high-speed data and video-on-demand services continues its seemingly eternal growth, the evolution of the access network progresses relentlessly towards expanded capacity and ever-smaller service groups. As a result, the spectrum allocated to narrowcast services increases, driving operators to deploy Data Over Cable Service Interface Specification (DOCSIS©) services including 32 SC-QAM (Single Carrier Quadrature Amplitude Modulation) channels and at least a fraction of an OFDM (Orthogonal Frequency Division Multiplexing) channel. In some cases Cable operators have even gone farther, to 36 and even 40 SC-QAM channels, and moving beyond a single OFDM channel onto a second one. In addition, if free spectrum in the network is not available, operators support capacity growth by segmenting service groups into smaller and smaller areas.
These expansion trends result in a continuous growth of headend equipment, which is already starting to exceed the capacity that headend facilities can support.
Therefore, the above trends are now intractably linked to two additional evolutions: distribution of components of the access network and virtualization of the core network functions. Furthermore, the implementation of a Distributed Access Architecture (DAA) is different in places where the plant is being upgraded, such as where a migration to a deeper use of fiber or N+0 is being implemented, versus in Cable networks where the existing plant needs to be segmented or expanded.
This paper will begin by outlining the evolution of service provider networks, and then describe why and how the migration to a distributed architecture is necessary and beneficial. The paper will then expand into features that can be implemented with Distributed Architectures and discuss the topic of Virtualization. Finally, the paper will explore how the implementation of DOCSIS 4.0 could be implemented in Distributed Architecture networks.