UPGRADE OF COAXIAL CATV NETWORKS FOR UPSTREAM HIGH-SPEED DIGITAL-COMMUNICATION

There is a growing interest to extend existing coax CATV networks to e nable interactive multimedia services. In this paper we describe neces sary modifications and additions of CATV network components to provide broadband upstream channels in the range of 6 to 40 MHz, To investiga te linear and nonlinear distortions, reflexions, noise and ingress, su itable digital modulation shemes and adaptive equalization, the CATV n etwork components are modelled and a computer simulation program using PTOLEMY is established. It is shown that all 3370 subscribers of an e xisting CATV sub-network can be provided with up to 25 kbit/s collisio n free on the physical network layer. Using appropriate teletraffic an d media access control protocols, user bit rates of up to 2 Mbit/s are feasible in upstream direction.