Space uncertain simulation events: some concepts and an application to optimistic synchronization

The notion of temporal uncertainty, expressed as the possibility for an event to occur in an interval of simulation time, rather than at a specific instant, has been recently proposed and exploited in order to enhance the performance of parallel/distributed simulation systems. In this paper, we propose the concept of "spatial uncertainty" expressed as the possibility for a simulation event to occur in one of a set of points within the simulated system space. How to handle/exploit space uncertain events in an optimistic simulation system is discussed. Also, experimental results for optimistic simulations of a personal communication system (PCS) modeled with space uncertain events are reported. These results show the ability of spatial uncertainty to increase the performance of the parallel simulation system by providing a more flexible approach to synchronization.