The television cable industry has become a major service provider by allowing data transport over upgraded CATV cable networks. The cable industry has had many plans for delivering unique services to its subscribers. High-resolution digital video has been part of the plan, as well as TV set-top boxes that provide interactive game interfaces, WebTV, and other features. Cable data networks make this possible.

This topic describes how broadband services are delivered over the “cable network.” It discusses the architecture of the cable network and several competing specifications that are attempting to define a universal cable network standard.

Cable data networks are one of several residential broadband schemes. Other schemes include DSL (Digital Subscriber Line), satellite systems such as Hughes Network System’s DirecPC, and wireless data systems discussed under “Wireless Broadband Access Technologies.” In fact, MMDS (Multichannel Multipoint Distribution Services) has been called a “wireless cable data network” solution because of its multipoint characteristics. See “Residential Broadband.”

CATV Architecture

The traditional CATV system consists of a shared coaxial cable network that transmits analog television signals to downstream subscribers. It is estimated that over 100 million homes are reachable by CATV cable, of which approximately 75 million of those homes are CATV subscribers.

The cable network mimics the over-the-air radio frequency broadcast signals that you would receive via a TV antenna, but they are carried on cable. Television signals are transmitted in 6-MHz channels.

CATV is a shared cable system that uses a tree-and-branch topology in which multiple households within a neighborhood share the same cable.