Negative Customers Research Articles

A BMAP/PH/N Queue with Negative Customers and Partial Protection of Service

A multi-server queueing system with finite and infinite buffers is considered. The input flow is described by the BMAP (Batch Markovian Arrival Process). The service time has the PH (Phase) type distribution. Besides ordinary (positive) customers, the MAP (Markovian Arrival Process) of negative customers arrives to the system. A negative customer can delete an ordinary customer in service if the state (phase) of its PH-service process does not belong to some given set of so-called protected phases. The stationary distribution of the system states and waiting time distribution are derived. The main performance measures of the queueing system considered are computed and numerically illustrated.

Analysis of the [formula omitted] [formula omitted]-queueing system with retrial customers

We consider a single server retrial queue with waiting places in service area and three classes of customers subject to the server breakdowns and repairs. When the server is unavailable, the arriving class-1 customer is queued in the priority queue with infinite capacity whereas class-2 customer enters the retrial group. The class-3 customers which are also called negative customers do not receive service. If the server is found serving a customer, the arriving class-3 customer breaks the server down and simultaneously deletes the customer under service. The failed server is sent to repair immediately and after repair it is assumed as good as new. We study the ergodicity of the embedded Markov chains and their stationary distributions. We obtain the steady-state solutions for both queueing measures and reliability quantities. Moreover, we investigate the stochastic decomposition law, the busy period of the system and the virtual waiting times. Finally, an application to cellular mobile networks is provided and the effects of various parameters on the system performance are analyzed numerically.

Analysis of stochastic Petri nets with signals

Product-form models facilitate the efficient analysis of large stochastic models and have been sought after for some three decades. Apart from the dominating work on queueing networks, some product-forms were found for stochastic Petri nets (SPNs) that allow fork-join constructs and for queueing networks extended to include special customers called signals, viz. G-networks. We appeal to the Reversed Compound Agent Theorem (RCAT) to prove new product-form solutions for SPNs in which there are special transitions, the firings of which act in a similar way to signals in G-networks, but which may be generated by synchronised firings (or service completions) and may affect several places simultaneously. We show that SPNs with signals are strict generalisations of G-networks with negative customers, triggers and catastrophes, and illustrate with copious examples.

Geo/Geo/1/N Queue with In-Immune and Immune Service Killing Discipline

The present investigation studies a discrete time single server queue with both positive and negative arrival streams in accordance with removal of the customer from the end (RCE)-in immune and immune service killing policy. This study is a generalization of the queue with negative customers, wherein only positive customers need a service and negative customers arriving to the system can kill the already present positive customers from any where in the queue, otherwise get lost. The concept of both in-immune and immune service killing are taken into consideration. According to the in-immune killing policy, the negative customer is allowed to kill the most recent positive customer inspite of whether it is in service or not, while the immune service killing discipline suggests that the customer currently being served is immune from killing by the negative arrival. We analyze a queue with geometric arrivals of both positive and negative customers for a finite capacity system. The stationary probability distribution and other performance measures are derived in terms of the generating functions. The results so obtained are validated by the numerical method based on successive over relaxation method (SOR). We have also employed the neurro fuzzy approach for exhibiting the approximate results for various performance measures.

On a BMAP/G/1 G-queue with setup times and multiple vacations

In this paper, we consider a BMAP/G/1 G-queue with setup times and multiple vacations. Arrivals of positive customers and negative customers follow a batch Markovian arrival process (BMAP) and Markovian arrival process (MAP) respectively. The arrival of a negative customer removes all the customers in the system when the server is working. The server leaves for a vacation as soon as the system empties and is allowed to take repeated (multiple) vacations. By using the supplementary variables method and the censoring technique, we obtain the queue length distributions. We also obtain the mean of the busy period based on the renewal theory.

An M/G/1 retrial G-queue with non-exhaustive random vacations and an unreliable server

This paper deals with an M/G/1 retrial queue with negative customers and non-exhaustive random vacations subject to the server breakdowns and repairs. Arrivals of both positive customers and negative customers are two independent Poisson processes. A breakdown at the busy server is represented by the arrival of a negative customer which causes the customer being in service to be lost. The server takes a vacation of random length after an exponential time when the server is up. We develop a new method to discuss the stable condition by finding absorb distribution and using the stable condition of a classical M/G/1 queue. By applying the supplementary variable method, we obtain the steady-state solutions for both queueing measures and reliability quantities. Moreover, we investigate the stochastic decomposition law. We also analyse the busy period of the system. Some special cases of interest are discussed and some known results have been derived. Finally, an application to cellular mobile networks is provided and the effects of various parameters on the system performance are analysed numerically.

A discrete-time on–off source queueing system with negative customers

This paper studies a discrete-time single-server infinite-capacity queueing system with correlated arrivals, geometrically distributed service times and negative customers. Positive customers are generated by a Bernoulli bursty source, with geometrically distributed lengths of the on-periods and off-periods. Negative customers arrive to the system according to a geometrical arrival process which is independent of the positive arrival process. A negative customer removes a positive customer in service if any, but has no effect on the system if it finds the system empty. We analyze the Markov chain underlying the queueing system and evaluate the performance of the system based on generating functions technique. Closed-form expressions of some performance measures of the system are obtained, such as stationary probability generating functions of queue length, unfinished work, sojourn time distribution and so on. Finally, the effect of several parameters on the system is shown numerically.

A Markovian queue with varying number of servers and applications to the performance comparison of HSDPA user equipment

Inspired by the need for performability models for HSDPA user equipment, a Markovian queue with varying number of servers is conceived. The arrival and the service processes, the number of allocated or active servers of the queue are inherently, and independently (or jointly) Markov modulated. Batch arrivals, batch services, autocorrelation of inter-arrival times, and autocorrelation of batch sizes can be accommodated in the queue, by a suitable use of Markov modulation and generalized exponential distribution. The queue has a provision for negative customers too. Transformations of the balance equations into a computable form are proposed in order to obtain the steady state probabilities with the Spectral Expansion method. This queue is used to model the High Speed Downlink Packet Access (HSDPA) wireless networks. The model is an integrated one with respect to HSDPA, capable of accommodating many of the intricate aspects of HSDPA such as, channel allocation policy, loss of packets due to channel fading, bursty and correlated traffic. Good agreement is observed between the numerical results of the proposed analytical model and those of an independent simulator of real HSDPA and radio channel behaviors. The comparison of the terminal categories specified by the 3rd Generation Partnership Project (3GPP) is also presented.

A preemptive resume priority retrial queue with state dependent arrivals, unreliable server and negative customers

In this paper we consider an unreliable single server retrial queue accepting two types of customers, with negative arrivals, preemptive resume priorities and vacations. A distinguishing feature of the model is that the rates of the Poisson arrival process depends on the server state. For this model we investigate the stability conditions and the joint queue length distribution in steady state. We also prove that our model satisfies the stochastic decomposition property. Transient, as well as steady state solutions for reliability measures are obtained. Finally, numerical results demonstrate the typical features of the model under consideration.

On a class of stochastic models with two-sided jumps

In this paper a stochastic process involving two-sided jumps and a continuous downward drift is studied. In the context of ruin theory, the model can be interpreted as the surplus process of a business enterprise which is subject to constant expense rate over time along with random gains and losses. On the other hand, such a stochastic process can also be viewed as a queueing system with instantaneous work removals (or negative customers). The key quantity of our interest pertaining to the above model is (a variant of) the Gerber---Shiu expected discounted penalty function (Gerber and Shiu in N. Am. Actuar. J. 2(1):48---72, 1998) from ruin theory context. With the distributions of the jump sizes and their inter-arrival times left arbitrary, the general structure of the Gerber---Shiu function is studied via an underlying ladder height structure and the use of defective renewal equations. The components involved in the defective renewal equations are explicitly identified when the upward jumps follow a combination of exponentials. Applications of the Gerber---Shiu function are illustrated in finding (i) the Laplace transforms of the time of ruin, the time of recovery and the duration of first negative surplus in the ruin context; (ii) the joint Laplace transform of the busy period and the subsequent idle period in the queueing context; and (iii) the expected total discounted reward for a continuous payment stream payable during idle periods in a queue.

An M/G/1 Bernoulli feedback retrial queueing system with negative customers

A single server retrial queue with negative customers and two types of Bernoulli feedback is considered. A necessary and sufficient condition for the system to be stable is investigated. The system size probabilities at output epochs are obtained by using an embedded Markov chain. Further, the joint generating functions of queue length and server status are studied by using supplementary variables method. Some important system performance measures are derived. Busy period of the system is also discussed. Finally, extensive numerical illustrations are provided.

A new solution for a queueing model of a manufacturing cell with negative customers under a rotation rule

In this paper, we consider a queueing model extension for a manufacturing cell composed of a machining center and several parallel downstream production stations under a rotation rule. A queueing model is extended with the arrival processes of negative customers to capture failures of production stations, reorganization of works and disasters in the manufacturing cell. We present an exact solution for the steady-state probabilities of the proposed queueing model. The solution does not require the approximation of the infinite sum. In addition, it provides an alternative way to compute the rate matrix for the matrix-geometric method as well.

Multiple Class Symmetric G-networks with Phase Type Service Times

We consider a queueing network of symmetric G-queues with customers and signals. Since the seminal papers by Gelenbe in the early 1990s (Gelenbe, E. (1991) Product-form queueing networks with negative and positive customers. J. Appl. Probab., 28, 656–663; Gelenbe, E. (1993); G-networks with instantaneous customer movement. J. Appl. Probab., 30, 742–748; Gelenbe, E. (1993) G-Networks with signals and batch removal. Probab. Eng. Inform. Sci., 7, 335–342), generalized networks of queues have received considerable attention. But most papers assume to obtain a product form such that the service times follow exponential distributions. Here, we propose a new generalization of this model with phase-type service times. We also assume a new type of signal. When a signal enters a queue, it changes the phase of the customer in service if there is any. As usual, after completion of its service, a customer moves to another queue and may become a signal. We prove that the steady-state distribution for such a network of queues has a product form solution.

Analysis of the finite source MAP/PH/N retrial G-queue operating in a random environment

Finite source retrial G-queues are good mathematical models of communication systems and networks, so their investigation is important for theory and applications. In this paper, we analyze the MAP/PH/N retrial queue with finite number of sources and MAP arrivals of negative customers operating in a finite state Markovian random environment. The arrival of a negative customer with equal probability goes to any busy server to remove the customer being in service. The multi-dimensional Markov chain describing the behavior of the system is investigated. The algorithms for calculating the stationary state probabilities are elaborated. Main performance measures are obtained. Illustrative numerical examples are presented.

A multi-server perishable inventory system with negative customer

In this paper, we consider a continuous review perishable inventory system with multi-server service facility. In such systems the demanded item is delivered to the customer only after performing some service, such as assembly of parts or installation, etc. Compared to many inventory models in which the inventory is depleted at the demand rate, however in this model, it is depleted, at the rate at which the service is completed. We assume that the arrivals of customers are according to a Markovian arrival process (MAP) and that the service time has exponential distribution. The ordering policy is based on (s,S) policy. The lead time is assumed to have exponential distribution. The customer who finds either all servers are busy or no item (excluding those in service) is in the stock, enters into an orbit of infinite size. These orbiting customers send requests at random time points for possible selection of their demands for service. The interval time between two successive request-time points is assumed to have exponential distribution. In addition to the regular customers, a second flow of negative customers following an independent MAP is also considered so that a negative customer will remove one of the customers from the orbit. The joint probability distribution of the number of busy servers, the inventory level and the number of customers in the orbit is obtained in the steady state. Various measures of stationary system performance are computed and the total expected cost per unit time is calculated. The results are illustrated numerically.

Bibliography on G-networks, negative customers and applications

The idea of G-networks with negative arrivals, as well as of the relevant product form solution including non-linear traffic equations, was first published by Erol Gelenbe in 1989. In contrast to classical queues and queueing networks, the arrivals of negative customers which remove customers from a non-empty queue upon their arrival are possible in G-networks. Negative customers with appropriate killing discipline can be used to model breakdowns and to model packet losses, etc., while triggered customer movement can represent control processes in networks. This work presents a bibliography 1 1 Similar bibliographies on retrial queues can be found in [J.R. Artalejo, A classified bibliography of research on retrial queues: progress in 1990–1999. Top 7 (1999) 187–211; J.R. Artalejo, Accessible bibliography on retrial queues, Mathematical and Computer Modelling 30 (34) (1999) 1–6; A. Gomez-Corral, A bibliographical guide to the analysis of retrial queues through matrix analytic techniques, Annals of Operations Research 141 (2006) 163–191; J.R. Artalejo, Accessible bibliography on retrial queues: progress in 2000–2009, Mathematical and Computer Modelling 51 (9–10) (2010) 1071–1081]. on G-networks, negative customers and the use of G-networks, negative customers and triggers to various performance analysis problems. We hope that we can include a majority of publications on G-networks. This bibliography in the BibTex format and a grouping by various themes is available online from http://www.hit.bme.hu/~do/G-networks/. We would encourage readers and researchers to send information to the author in order to make this bibliography as complete as possible.

A new performability model for queueing and FDL-related burst loss in optical switching nodes

Optical packet and burst switching have been proposed for networks because of the increased demand for capacity to transport traffic generated by various applications at present and in future. In optical packet switching networks the payload and the header of a packet are conveyed in the same channel, while burst switching networks allow the separate transportation of the payload and the header of bursts. In this paper we propose a queueing model for an optical node with a number of wavelengths and a buffer made from Fiber Delay Loops (FDL). We also apply negative customers in the queueing model in order to account for the loss of bursts due to the limitation related to the FDL (i.e. bursts can stay in a FDL buffer only for a limited period of time). Numerical results based on the analytical model are compared to the results obtained by simulation of optical burst switching nodes with the FDL buffer and input traffic using packet traces from the Internet Traffic Archive, which shows the accuracy of the proposed model.

Strong stability of the embedded Markov chain in an GI/M/1 queue with negative customers

This paper is devoted to the investigation for sufficient conditions of the strong stability of the embedded Markov chain in GI/M/1 queueing system with negative customers. After perturbing the occurrence rate of the negative customers, we prove the strong stability of the considered Markov chain with respect to a convenient weight variation norm. Furthermore, we estimate the deviation of its transition operators and provide an upper bound to the approximation error. This results allow us to understand how the negative customers will affect the system’s level of performance.

The Geo/G/1 Queue with Negative Customers and Disasters

The arrival of a negative customer to a queueing system causes one positive customer to be removed if any is present. On the other hand, the arrival of a disaster removes all the customers in the system. The discrete-time Geo/Geo/1 queue, which has either negative customers or disasters, has recently appeared in the literature[ 3 , 4 ]. We extend this Geo/Geo/1 queue to the Geo/G/1 queue. In so doing, we present both models' probability generating function of the stationary queue length and sojourn time, respectively. We also provide some numerical examples to illustrate the effect of the parameters on these queueing models.

An M/G/1 retrial G-queue with preemptive resume and feedback under N-policy subject to the server breakdowns and repairs

An M / G / 1 retrial G -queue with preemptive resume and feedback under N -policy vacation subject to the server breakdowns and repairs, is investigated in this paper. Arrivals of both positive customers and negative customers are two independent Poisson processes, and positive customers receive service immediately if the server is free upon their arrivals. Otherwise, they may enter a retrial orbit and try their luck after a random time interval. All positive customers must receive preliminary first phase of service and primary second phase of service. While at the preliminary service, the server may push out the customer undergoing such service to the orbit, to commence preliminary service of an arriving positive customer. Negative customers not only remove the customer being in service, but also make the server under repair. The server leaves for an N -policy vacation as soon as the system empties. By applying the supplementary variables method, we obtain the steady-state solutions for both queueing measures and reliability quantities. The effects of various parameters on the system performance are analyzed numerically.