Preventive maintenance in an unreliable M/G/1 retrial queue with persistent and impatient customers

In this paper we study a new version of an unreliable retrial queue with persistent and impatient customers. The considered model takes into account corrective and preventive maintenances. If a preventive action occurs in a busy period, then it is postponed to an ulterior date. We give the necessary and sufficient condition for the system to be stable and obtain the joint distribution of the server state and the number of orbiting customers in the system in terms of generating functions. Some performance measures are derived. From the reliability view point, we analyze the time to the first failure of the server. The effect of the system parameters on the performance measures is shown through an illustrative numerical example.