Basic composition, equipment and functions of telephone communication network

A system that transmits information between users in different places. It belongs to electromagnetic system, also called telecommunication network. It is an organic whole composed of many interdependent and mutually restrictive elements to complete the prescribed functions. The function of communication network is to meet the call demand of users, and exchange information between any two or more users in the network to achieve user satisfaction. Generally, the number and location of terminal equipment are given, and the network structure refers to the capacity and configuration of switching equipment and transmission channels. These are related to service distribution, connection standards, stability standards and the cost ratio between switching equipment and transmission channels. There are many kinds of networks. When the exchanges are scattered and the communication between exchanges is small, or when the transmission cost is higher than the exchange cost, for example, for long-distance telephone networks, star networks are usually used. Mesh networks are often used in short-distance or long-distance situations with large traffic or transmission costs lower than switching costs. For example, the ring network can communicate in both directions, so the reliability is improved. Cellular network and mesh network are relatively complex in structure, but they are mostly used in mobile communication networks because of their high routing freedom, high traffic processing efficiency and high reliability. Multi-grid networks and polyhedral networks are used in military communication networks because of their numerous routes, which improve their reliability. When the communication network is large, the whole area is generally divided into several grades of partitions, and the optimal structure is gradually adopted in each partition and each partition.