Discrete event systems with real-time constraints: modeling and sensitivity analysis

The authors present a model for timed discrete-event systems (DES) that includes conditioned event, a situation arising in the presence of real-time constraints. Based on this model, an augmented system approach is developed to determine conditions for constructing perturbed simple paths of such a DES, given only a nominal sample path. A queueing system with real-time constraints is then considered, where jobs are accepted into a service facility with threshold-based access control and are lost if their waiting time exceeds a given deadline. An augmented system model is constructed to estimate performance sensitivities online with respect to the threshold parameter. It is shown that this approach provides consistent estimates of these sensitivities under certain conditions, and explicit procedures for obtaining these estimates are presented