Approximating the Mean Time in System in a Multiple-Server Queue that Uses Threshold Scheduling

In this paper we consider a queueing system consisting of a single queue with multiple exponential servers with different servicing rates. We assume that arrivals to the queue come from a Poisson source and are scheduled according to a threshold policy. Since determining the exact mean time in system appears to be difficult, we present an approximation that yields results very close to those obtained from simulation.