ANALYSIS OF FINITE BUFFER HEAD-OF-THE-LINE PRIORITY-QUEUES WITH PUSH-OUT SCHEME AS SPACE PRIORITY

This paper analyzes a finite buffer M/G/1 queue with two classes of cu stomers who are served by a combination of head-of-the-line priority a nd push-out schemes. This combination gives each class of customers tw o different types of priorities with respect to both delay and loss. T here are two models considered. The first one is that one class of cus tomers has a higher priority over the other class with respect to both delay and loss; the second one is that one class has a higher priorit y with respect to loss and the other has high-priority with respect to delay. For both of these models, the joint probability distribution o f the number of customers of both classes in the buffer is derived by a supplementary variable method. Using this probability distribution, we can easily calculate the loss probabilities of both classes, the me an waiting time for high-priority customers with respect to loss and t he upper bound for mean waiting time for low-priority customers with r espect to loss. Numerical examples demonstrate an effect of the combin ation of different types of priorities.