Unreliable retrial queues due to service interruptions arising from facsimile networks

Queueing systems with retrials arise naturally in telecommunications and computer systems. The increasing interest on this topic is mainly explained by the development of new facilities in telecommunication technology such as ‘repeat last number’, ‘ring back when free’, etc. In this paper we concentrate our attention in the reliability of the system when the server is subject to interruptions. We consider a retrial queueing system with service interruptions arising from facsimile networks. We first investigate the joint distribution of the channel state and the number of customers in the retrial group in the steady state. We show that the queue length characteristics reduce to closed form expressions for the case of exponential service times. Using some results from the theory of regenerative processes, we also obtain some other important performance measures.