Negative arrivals are used as a control mechanism in many telecommunication and computer networks. This paper analyses a discrete-time single-server queue with geometrical arrivals of both positive and negative customers. We consider both the cases where negative customers remove positive customers from the front and the end of the queue and, in the latter case, the two sub-cases in which a customer currently being served can and cannot be killed by a negative customer. Thus, we carry out a complete study of these systems, including the ergodicity condition as well as exact formulae for the associated stationary distribution. The effect of several parameters on the systems is shown numerically.
This paper discusses a discrete-time Geo/G/1 retrial queue with the server subject to breakdowns and repairs. The customer just being served before server breakdown completes his remaining service when the server is fixed. The server lifetimes are assumed to be geometrical and the server repair times are arbitrarily distributed. We study the Markov chain underlying the considered queueing system and present its stability condition as well as some performance measures of the system in steady-state. Then, we derive a stochastic decomposition law and as an application we give bounds for the proximity between the steady-state distributions of our system and the corresponding system without retrials. Also, we introduce the concept of generalized service time and develop a recursive procedure to obtain the steady-state distributions of the orbit and system size. Finally, we prove the convergence to the continuous-time counterpart and show some numerical results.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.