A TWO-WAY MULTIPLE ACCESS COMMUNICATION SYSTEM, AND A CENTRAL STATION AND A USER STATION FOR USE IN SUCH A SYSTEM

摘要

A CATV system (1) operating as a two-way multiple access communication system in which a plurality of user stations (US1 to US5) communicate with a central station (CS) which can provide video programs. The system (1) can be an interactive TV system in which the user stations (US1 to US5) can order a specific program, or can respond to multiple choice questions in a program, or the like. For exchanging session accompanying information between the central station (CS) and the user stations (US1 to US5) a common control channel is provided. For true interactivity in high capacity and high user density systems, session accompanying control information is exchanged between the central station (CS) and the user stations (US1 to US5) via dedicated control channels (DSCS, USCS). Such a system (1) satisfies the needs of all kinds of multi-media systems, interactivity being an important feature in such systems.