3 - Communication Network Structure

Abstract

Telephone network was constructed as a communication network. Advances in information processing technology and new communication services such as data communication service and facsimile communication service have been implemented by using the telephone network. To interconnect terminals, computers, and networks, the network architecture and protocol have been developed. The conventional telephone network has been hierarchically structured. There are toll switching (TS) systems and local switching (LS) systems. With advances in telecommunication network, the network structure became simple. A two-layered structure including LS and TS has been used in Japan in its public telephone network. When the line is busy, an alternate line is selected and the call is transmitted through an alternate route. Recently, it has become increasingly necessary to transmit multimedia information in real time via communication lines. To accomplish this, high-speed transmission lines or digital transmission lines have been constructed. The high-speed and digital transmission networks are called the Information Superhighway. The high-speed network project has been conducted in the public telephone network.