Browsing by Subject "Retrial queueing systems"

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Open Access
Analysis of Markov multiserver retrial queues with negative arrivals
(Springer, 2001) Anisimov, V. V.; Artalejo, J. R.
Negative arrivals are used as a control mechanism in many telecommunication and computer networks. In the paper we analyze multiserver retrial queues; i.e., any customer finding all servers busy upon arrival must leave the service area and re-apply for service after some random time. The control mechanism is such that, whenever the service facility is full occupied, an exponential timer is activated. If the timer expires and the service facility remains full, then a random batch of customers, which are stored at the retrial pool, are automatically removed. This model extends the existing literature, which only deals with a single server case and individual removals. Two different approaches are considered. For the stable case, the matrix–analytic formalism is used to study the joint distribution of the service facility and the retrial pool. The approximation by more simple infinite retrial model is also proved. In the overloading case we study the transient behaviour of the trajectory of the suitably normalized retrial queue and the long-run behaviour of the number of busy servers. The method of investigation in this case is based on the averaging principle for switching processes.
Open Access
Asymptotic analysis of highly reliable retrial queueing systems
(2000) Kurtuluş, Mümin
The thesis is concerned with the asymptotic analysis of the time of first loss of a customer and the flow of lost customers in some types of Markov retrial queueing systems with flnite buffer. A retrial queueing system is characterized by the following feature: an arriving customer finding all of the servers busy must leave the service area and join a special buffer. After this it may re-apply for service after some random time. If the buffer is full the customer is lost. The analysis of the time of first loss of a customer is based on the method of so-called S — sets and the results about the asymptotic behavior of the first exit time from the fixed subset of states of semi-Markov process of a special structure (so-called monotone structure). Single server retrial queueing systems [M IM IlIm with retrials) as well as multiple server retrial queueing systems {M IM fsfm with retrials) are analyzed in cases of fast service and both fast service and fast retrials. Exponential approximation for the time of first loss and Poisson approximation for the flow of lost customers are proved for all of the considered cases.
Open Access
Averaging methods for transient regimes in overloading retrial queueing systems
(Elsevier, 1999) Anisimov, V. V.
A new approach is suggested to study transient and stable regimes in overloading retrial queueing systems. This approach is based on limit theorems of averaging principle and diffusion approximation types for so-called switching processes. Two models of retrial queueing systems of the types M̄/Ḡ/1̄/w.r (multidimensional Poisson input flow, one server with general service times, retrial system) and M/M/m/w.r (m servers with exponential service) are considered in the case when the intensity of calls that reapply for the service tends to zero. For the number of re-applying calls, functional limit theorems of averaging principle and diffusion approximation types are proved.