Which Connection Technology Uses What Is Known As A Cmts?

September 11, 2023
David Sunnyside

What Is Known As A Cmts

A cable modem termination system, or CMTS, is network equipment that sits at a cable company's hub site. It communicates with a cable modem in the customer's home to route data between the Internet and television channels.

The DOCSIS standard divides the bandwidth of the cable TV network into multiple channels, with each channel carrying different types of data. This allows cable operators to offer high-speed data services without affecting television service. Cable modems that conform to DOCSIS use the same protocol to communicate with a CMTS and get the requested bandwidth.

Traditionally, cable CMTSs were integrated chassis that housed all the signal processing and DOCSIS functions. This approach is being replaced by Distributed Access Architecture (DAA), which breaks the CMTS into modular components and moves them closer to the cable modems in the node. The two most important modular CMTS components are the PHY circuit, which is called Edge QAM, and the DOCSIS MAC component.

Both of these parts are now being moved out of the headend CMTS and closer to the subscriber's cable modems in a new technology called Remote-PHY DAA. This is a major shift in the CMTS - node relationship that will lead to further consolidation and virtualization of the entire MSO access network.

In a Remote-PHY CMTS, the PHY circuit of the CMTS is moved out to digital fiber nodes that sit close to subscribers' cable modems. These nodes receive the digital signals from the CMTS over an optical link, convert them to analog signals, and deliver them to the end user. Upstream signals from the end user are received by the R-PHY node, digitized, and then sent back to the CMTS over the optical link.

David Sunnyside
Co-founder of Urban Splatter • Digital Marketer • Engineer • Meditator
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