Al-Begain K., Barner J., Bolch G., Zreikat A.


The paper aims to demonstrate the applicability of the new and powerful performance and reliability modelling language MOSEL (MOdeling, Specification and Evaluation Language) through examples from queueing networks with finite capacity, retrial systems and mobile networks. MOSEL is a high level modelling language that allows the modeling and performance evaluation of systems in a very intuitive and simple way. The core of MOSEL consists of constructs to specify the possible states and state transitions of the underlying Continuous-Time Markov Chain (CTMC) of the system under consideration. This specification is very compact and easy to understand. With additional constructs the interesting performance or reliability measures and also the graphical presentation of them can be specified. It is specially easy to do experiments with different sets of parameters of the system. The examples chosed to demonstrate the modelling power of MOSEL come from three application areas. First, models of queueuing networks with finite capacity are presented which are very important for the performance modelling of computer and manufacturing systems. The finite capacities of the nodes of the network generates blocking at previous nodes. In the second example a retrial system is medelled. In a retrial system an arriving customer, if he finds the server idle, is served immediately. If the server is busy the customer leaves and tries his luck again after a randomly distributed amount of time independent of any other events. This happens for example in telephone systems, in supermarkets or at airports when aircrafts are waiting for landing permission. The third example presents a model a real system from wireless communications. In this example, the call admission control protocol in a Third Generation (3G)wireless mobile network is studied. In all examples, results on blocking probabilities, utilization, and response times are shown. The graphical representation of these results is done using IGL (Intermediate Graphical Language) which a complementary package to MOSEL.

International Journal in Simulation: Systems, Science and technology, Vol. 3, No. 3-4, pp. 66-80, 2003.