As the demand for bandwidth and services increases, cable operators are looking for ways to scale their networks more efficiently and cost-effectively, which has led many to move from the traditional, integrated, CMTS to Distributed Access Architecture (DAA).
The move to DAA is a significant evolution in the way cable operators deliver high-speed internet and other services over their networks. The traditional CMTS architecture was built around a centralized, integrated CMTS chassis that provided all the signal processing and DOCSIS functionality for a particular service group or node. DAA moves some of the signal processing and DOCSIS functionality out of the CMTS chassis and closer to the end user in the access network.
Several DAA architectures have emerged over the years, including R-PHY, vCCAP, Remote MAC, and Fiber Deep:
- R-PHY: The physical layer (PHY) of the DOCSIS signal processing is moved to a small device called an R-PHY node closer to the end user, which receives digital signals from the CMTS over an optical link, converts them to analog signals, and sends them over the coaxial cable network to the end user. Upstream signals from the end user are received by the R-PHY node, digitized, and sent back to the CMTS over the optical link.
- vCCAP: CMTS functionality is virtualized and run on commodity servers in the cable operator's data center, rather than on a dedicated CMTS chassis. The physical layer of the DOCSIS signal processing is still located in a small node, similar to an R-PHY node, but the node is simpler and doesn't require as much processing power as an R-PHY node.
- Remote MAC: The MAC (media access control) layer of the DOCSIS signal processing is moved closer to the end user, with the CMTS sending necessary software and configuration data to a small, low-cost MAC node located in the access network. The MAC node handles the upstream and downstream media access control functions for a subset of the service group or node.
- Fiber Deep: Fiber-optic cable is run to a point closer to the end user, such as a neighborhood or street, and a small, low-cost node with DOCSIS processing capabilities is installed at that location. The node converts the fiber-optic signals to coaxial cable signals, amplifies them, and sends them over the coaxial cable network to the end user.
Each of these DAA architectures has its own advantages and trade-offs, and cable operators choose the one that best fits their needs and network requirements. The move to DAA is expected to continue in the coming years as cable operators seek to enhance the efficiency and scalability of their networks, support the growing demand for higher bandwidth and low-latency applications, and explore new opportunities for revenue growth.