Performance simulation of non-reliable servers in finite-source cognitive radio networks with collision

Abstract

This paper introduces a finite-source retrial queueing system which models cognitive radio networks. We assume two non-independent frequency bands servicing two classes of users: Primary Users (PUs) and Secondary Users (SUs). A service unit with a priority queue and another service unit with an orbit are assigned to the PUs and SUs, respectively. In this work, we focus on the non-reliability of the servers and the collisions at the secondary servers. The primary and secondary servers are subject to random breakdowns and repairs. A collision is introduced at the retrial part of the cognitive radio network. This conflict invokes the interruption of a servicing packet when a new arriving call requests the server unit. The novelty of the investigation is the non-reliability of servers and the inclusion of conflicts at the secondary server. By the use of simulation, we analyze the effect of the non-reliability of the servers on the mean response time of the secondary users.