Upgrading CATV systems for interactive services

The introduction of digital TV simultaneously involves the start of new multimedia services. After having terminated a transmission standard for satellite and cable, the DVB project also set up a specification for the return channel. Many of the new services in question require bidirectional communication channels but the data rate to be transmitted is relatively low, as these data services are mainly asymmetrical. In parallel to the new multimedia services for CATV systems, the CATV network is discovered as an access network for other telecommunication applications. The combination of both aspects allow for interesting synergy effects and will therefore contribute to a cost-efficient usage of these networks. The different ownerships of the individual network sections require careful planning providing definite interfaces at the boundaries of the network sections. A reference model should help to make planning transparent. This paper discusses a "radio in the local loop" DECT system as a subscriber access network for telephony and presents a system for CATV applications as an alternative to microwave radio transmission, based on the same technology. Cable-bound transmission allows for using frequency resources much more economically.