THE M/G/1 QUEUE WITH PERMANENT CUSTOMERS

This paper is concerned with an M/G/1 FCFS queue with two types of customers, viz. (1) ordinary customers who arrive according to a Poisson process, and (2) permanent customers, who immediately return to the end of the queue after having received a service. The influence of the permanent customers on queue length and sojourn times of the Poisson customers is studied, using results from queueing theory and from the theory of branching processes. In particular it is shown, for the case that the service time distributions of the Poisson customers and all K permanent customers are negative exponential with identical means, that the queue length and sojourn time distributions of the Poisson customers are the (K + 1)-fold convolution of those for the case without permanent customers.