Homogeneous finite-source retrial queues with server subject to breakdowns and repairs

This paper deals with a single server retrial queue with a finite number of homogeneous sources of calls and a single nonreliable server, which means that the server is subject to random breakdowns depending on whether it is busy or idle. The failure of the server may block or unblock the systemsʹ operations and the service of the interrupted request may be resumed or the call can be transmitted to the orbit. All random variables involved in the model constructions are supposed to be exponentially distributed and independent of each other. velty of the investigation is the variability of this nonreliability of the server which makes the system rather complicated. The MOSEL tool was used to formulate and solve the problem and the main performance and reliability measures were derived and graphically displayed. Several numerical calculations were performed to show the effect of the nonreliability of the server on the mean response times of the calls.