The Telecommunications Handbook: Engineering Guidelines for Fixed, Mobile and Satellite Systems

4 Protocols

Jyrki T. J. Penttinen

4.1 Introduction

The protocols are the basis for practically all the data flows of the modern communications systems. The benefits of protocols include the fluent methods of functionality, and in an ideal world, protocols at their levels are capable of understanding the protocols of any other equipment of the same system regardless of manufacturers. In practice, this is rarely the case in wider environments, but in any case, good work has been done in international standardization in order to create as compatible system blocks as possible.

The physical aspects of the connection include the selection of signal types, voltage levels, connector types, cabling and network topology. For a direct, dedicated point-to-point communication only between two users it would be straightforward to send and receive signal levels according to a certain rule such as modulation and demodulation of the signal, for example, in the walkie-talkie connection. Nevertheless, for wider communications even for point-to-point cases, there are hardly ever any possibilities of applying this method. Furthermore, various network elements are involved in the communications route. This means that there needs to be a commonly agreed way in which the communication is handled between network nodes to deal with, for example, the collision of multiple access attempts of users, error recovery, resending, and so on. Protocol basically refers to the standardized method of transmission ...