Cable Modem Termination System

A Cable Modem Termination System (short: CMTS ) is a component that is usually in a cable headend ( headend ) and high -speed data services, such as Internet or Voice over Cable cable user provides. Depending on the version, a CMTS to serve 50,000 households (as of spring 2004).

Essential components of a CMTS

MAC processor

The MAC processor is responsible for the management of cable modem.

Scheduler

In close coordination with the MAC processor, the scheduler is responsible for the management of the upstream channel resources.

WAN interface

The WAN interface is the interface to the IP network. The interface can be implemented as a router as well as a bridge.

Downstream modulator

Downstream of the modulator or transmitter unit modulates the data sent from the Internet, to a carrier, and transmits the data to the cable modem. The transmitting unit to operate in a frequency range of 88-860 MHz and 88-862 MHz DOCSIS EuroDOCSIS.

Upstream demodulator

The upstream demodulator or receiving unit receives the data sent from the cable modem to the CMTS. Depending on the number of clusters or Koaxzellen, which in turn depends on the size of the cable network and the number of operated cable modems, there is one or more upstream demodulators. The receiving unit operates in a frequency range of 5-65 MHz in accordance with European Standard ( EuroDOCSIS ) or in a frequency range of 5-42 MHz by U.S. standards ( DOCSIS ).

Interconnection of downstream and upstream

To put the number of upstreams and downstream to a physical line, these are combined via combiners or turnouts.