MODELING AND SIMULATION OF COMMUNICATION-SYSTEMS

The design of digital radio communication systems involves the definit ion of the system architecture (for example, network topology and prot ocols), the design and modelling of the algorithms and the behaviour o f the system (for example, signal processing functions), the design of the hardware/software architecture to be employed and finally, implem entation of the algorithms on the chosen architecture. During this des ign life cycle the performance of the communications system can be eva luated in three ways; the paper will briefly discuss the characteristi cs of these methods and highlight when computer modelling/simulation i s the best and most efficient way for-ward in order to gain an underst anding of a communication system and an estimate of its performance. T he paper discusses the migration from computer modelling using standar d high-level languages such as FORTRAN towards the rise of high-level design and simulation packages. It is shown how such a commercially-av ailable package was used to model the physical layer of a public air-t o-ground telephone system. The paper also shows how the modelling acti vity was used within the standardization process and how these new too ls allow models to evolve easily, introducing more and more derail unt il it represents a very accurate model of the real system. We subseque ntly show how the computer model was used to assist in the implementat ion and testing phase of the project. Finally, the paper discusses the concept of rapid prototyping and its advantages and shows how such a modelling tool can also be used to produce prototype equipment.