Applying a modified Chandy-Misra algorithm to the distributed simulation of a cellular network

The performance of the Chandy-Misra algorithm in distributed simulation has been studied in the context of a particular simulation application: a cellular network. The logical process structure under the algorithm is modified in such a way that the excessive synchronisation caused by the algorithm can be avoided. The synchronisation is minimised by reducing the number of connections between logical processes (LP). The concept of a neighbourhood of an LP is defined in such way that an LP is connected via logical channels only to those LPs that belong to its neighbourhood. A broadcast messages method is proposed to solve the communication between non connected logical processes, i.e. those outside the neighbourhood. Simulation experiments are carried out in a previously implemented distributed simulation environment, Diworse. A GSM network is used as a simulation application where target of the simulation is to obtain estimates for the channel utilisation. Carrier per interference (C/I) values for GSM channels are used for determining the need for handovers. Execution time of the simulation and deviations in the C/I values are measured for completely connected and broadcast message methods in order to find out the effect of connection reduction. The results indicate that the broadcast messages method enables significantly faster simulation. With the GSM application, the proposed method has only a negligible distorting effect on the simulation.