System Element Models

In building a suitable model for a queueing system, we start with its elements. Of the elements mentioned in Chapter 1, number of servers, system capacity, and discipline are normally deterministic (unless, the number of available servers becomes a random variable, which is also possible in some cases). But there are uncertainties related to arrivals and service which result in the underlying processes being stochastic. This chapter introduces probability distributions normally used in modeling arrivals and service. We also discuss the process of identification of models.