Queueing Systems with Service Interruptions

In many queueing systems, the service process is subject to interruptions resulting from breakdowns, scheduled off-periods or the arrival of customers with preemptive priority. We consider a single server, first-come, first-served queueing system that alternates between periods when service is available (“on-periods”) and periods when the server is unavailable (“off-periods”). We consider the case of Poisson arrivals and general service, on- and off-time distributions and derive bounds and approximations for the mean waiting time, probability of delay and steady-state distribution of the number in system. These results are exact for the case of exponentially distributed on-times. Computational results are reported.