Convergence of Probability Measures. By P. Billingsley. Chichester, Sussex, Wiley, 1968. xii, 253 p. 9 1/4“. 117s.

Convergence of Probability Measures

Review: A systematic review on clustering and routing techniques based upon LEACH protocol for wireless sensor networks

Retrial queues have been widely used to model many problems arising in telephone switching systems, telecommunication networks, computer networks and computer systems, etc. It is of basic importance to study reliability of retrial queues with server breakdowns and repairs because of limited ability of repairs and heavy influence of the breakdowns on the performance measure of the system. However, so far the repairable retrial queues are analyzed only by queueing theory. In this paper we give a detailed analysis for reliability of retrial queues. By using the supplementary variables method, we obtain the explicit expressions of some main reliability indexes such as the availability, failure frequency and reliability function of the server. In addition, some special queues, for instance, the repairable M/G/1 queue and repairable retrial queue can be derived from our results. These results may be generalized to the repairable multi-server retrial models.

Reliability Analysis of the Retrial Queue with Server Breakdowns and Repairs

Denial of service (DoS) is a prevalent threat in today's networks because DoS attacks are easy to launch, while defending a network resource against them is disproportionately difficult. Despite the extensive research in recent years, DoS attacks continue to harm, as the attackers adapt to the newer protection mechanisms. For this reason, we start our survey with a historical timeline of DoS incidents, where we illustrate the variety of types, targets and motives for such attacks and how they evolved during the last two decades. We then provide an extensive literature review on the existing research on DoS protection with an emphasis on the research of the last years and the most demanding aspects of defence. These include traceback, detection, classification of incoming traffic, response in the presence of an attack and mathematical modelling of attack and defence mechanisms. Our discussion aims to identify the trends in DoS attacks, the weaknesses of protection approaches and the qualities that modern ones should exhibit, so as to suggest new directions that DoS research can follow.

Protection Against Denial of Service Attacks

In this paper we survey work related to queues with interruptions that occur due to many reasons such as server breakdowns, servers taking emergency breaks, and customers having incomplete information or getting distracted We look at both continuous and discrete time queueing models with interruptions in this survey

Queues with interruptions: a survey

This paper deals with a single server retrial queueing system subject to active and independent breakdowns. The objective is to extend the results given independently by Aissani l1r and Kulkarni and Choi l15r. To this end, we introduce the concept of fundamental server period and an auxiliary queueing system with breakdowns and option for leaving the system. Then, we concentrate our attention on the limiting distribution of the system state. We obtain simplified expressions for the partial generating functions of the server state and the number of customers in the retrial group, a recursive scheme for computing the limiting probabilities and closed-form formulae for the second order partial moments. Some stochastic decomposition results are also investigated.

On the single server retrial queue subject to breakdowns

Performance evaluation of network lifetime spatial-temporal distribution for WSN routing protocols

Retrial queues are useful in the stochastic modelling of computer and telecommunication systems amongst others. In this paper we study a version of the retrial queue with variable service. Such a point of view gives another look at the unreliable retrial queueing problem which includes the redundancy model.

A retrial queue with redundancy and unreliable server

Sensor placement is a fundamental issue in wireless sensor networks (WSNs). The sensor–positions can be predetermined to guarantee the quality of surveillance provided by the WSN. However, in remote or hostile sensor field, randomised sensor placement often becomes the only option. In this paper, we survey existing random node placement strategies. We categorise random placement strategies into simple and compound. An empirical study has been carried out yielding a detailed analysis of random deployment intrinsic properties, such as coverage, connectivity, fault–tolerance, and network lifespan.We also investigate the performance of a hybridisation of the simple diffusion model that places a large number of nodes around the sink and the constant diffusion that provides high coverage and connectivity rates. We show that such hybridisation ensures better performance. The obtained results give helpful design guidelines in using random deployment strategies.

Random deployment of wireless sensor networks: a survey and approach

A key challenge in the success of wireless sensor networks deployment is to consider the imperfections associated with sensor readings. Existing sensor coverage models such as the binary model and the probabilistic model may not be realistic in many cases and remain limited. Based on the transferable belief model, this letter defines an evidence-based sensor coverage model that reflects reality well and can be easily extended to include deployment-related issues, such as sensor reliability. As an example of application, we devise an evidence-based detection coverage model. Experimental results based on both synthetic data sets and data traces collected in a real experiment for vehicle detection are provided to demonstrate the benefits of the evidence-based sensor coverage model over state-of-the-art coverage models.

Amar Aissani

Papers

On the single server retrial queue subject to breakdowns

Performance evaluation of network lifetime spatial-temporal distribution for WSN routing protocols

A retrial queue with redundancy and unreliable server

Random deployment of wireless sensor networks: a survey and approach

An Evidence-Based Sensor Coverage Model