Planning of a Digital Hierarchy

The choice of the fundamental parameters of a pulsecode modulation (PCM) system hierarchy depends on many factors, such as transmission media characteristics, time division switching and multiplexing plant requirements, traffic demand and network topology, etc. This paper deals with the problem of clarifying these interdependences and gives the general design criteria for planning a digital hierarchy. In accordance with these criteria, the main characteristics of a digital hierarchy, starting from the 2.048-Mbit/s primary PCM system, are derived and proposed. At present, systems in accordance with this proposal are being developed in Italy.