Fiber has greatly increased the capacity and reliability of cable TV networks. With a cable Internet connection, data occupy the space of one TV channel. The fiber network also allows signals to be sent back from the home to the head end, making telephone and interactive video services possible. About half of all North American cable homes already have this two-way capability, fewer in Europe and Asia. More than a Modem A cable modem can connect to more than one PC in the home, with excellent support for in-home networks.
Cable modems use a number of advanced techniques to perform their duties.
Because the coaxial cable is shared within a neighborhood, the modems must equitably dole out bandwidth to customers, ensuring that no single customer can monopolize the total available bandwidth. As the number of users grows, the cable operator shrinks each service area to maintain adequate bandwidth. All data transmitted over the cable network are encrypted for privacy, and each modem has its own unique cryptographic key. Automated software updates for the modems can be centrally coordinated, and service anomalies can be flagged without human intervention. Early-warning signals from the modems let the provider respond to problems before they affect service.