Communication Networks Economy

2Network Structure and Architecture

This chapter provides a general overview of the major elements necessary for establishing the connections which allow applications to be distributed across a network. It also takes the opportunity to recall some conditions essential for providing a good quality of service without requiring excessive expenditure. Aspects relating to the major applications, terminals and network staff are also examined.

2.1. Analog and digital

2.1.1. Terminology

The information to be conveyed across networks comes in two forms: analog and digital. The analog form has a continuous signal, even if its amplitude or intensity varies. Digital information, on the other hand, is irregular and is made up of discrete values. The spoken word and music are universally considered to have an analog form. In telecommunications, digital technology uses components that have only two possible electrical states. Transistors perfectly convert binary signals, ones and zeroes, plus signals (+) and minus signals (–) from a telegraph or computer.

2.1.2. Historical overview

Until 1970, it was thought that telephone circuits should be used to transmit speech signals with analog technology and that digital technology should be left to data transmission and telegraphy. However, due to the availability of new components, it then became apparent that regional carriers could have an increased number of transmission circuits by implementing digital technology. The progressive improvement ...