Application of discrete event simulation to network protocol modeling

Discrete event simulation (DES) is a computer based simulation method which is particularly effective for modeling the performance of systems which are driven by activities occurring at discrete instants in time (events). Such simulations can serve as an effective tool to evaluate the performance of communication systems carrying a diverse mix of traffic. The development of personal communications systems (PCS) is expected to require the evaluation of the effectiveness of various communications protocols that handle complex traffic mixes such as voice, data, and specialized messaging. Modern commercial software facilitates simulation development by providing a graphical interface with appropriate building blocks for common functions. This paper illustrates the use of this procedure through a basic queuing model representing the priority queuing process used in systems. The model presented shows capacity limitations of a simple queuing system in which a stream of voice traffic contends with a stream of data traffic. To ensure continuity of voice messages, voice traffic is given priority over data traffic. More complex aspects of communication protocols may be simulated by incorporating additional detail in the model at the expense of computer simulation time.