Hierarchical structure of telecommunication network with independent transversal trunks

The main objective of setting up the hierarchical structure for telecommunication network is to concentrate the traffic in order to increase the efficiency of transmission lines, thereby reducing the total cost of the network. The optimum structure of the network is determined by such factors as traffic, its flow pattern, the costs of transmission line and switching equipment. The costs of components of the switching network change rather rapidly due to recent technological development. The change of cost and the role of transversal trunks in handling traffic calls have made the reconsideration of installing transversal trunks worthwhile. This paper presents a geometrical model for the Japanese public telephone network. The optimization of the hierarchical structure of the network is performed taken into consideration such parameters as costs of transmission lines, switching facility, and traffic threshold for transversal trunk. It is concluded that the three‐stage network with end offices, toll centers, and district centers seems appropriate in the near future. The district center of this network should be about the same scale as the existing regional center. The traffic threshold for installing the transversal trunk should be almost several tens of erlangs.