Modelling and performance analysis of mobile ad hoc networks

PhD ThesisMobile Ad hoc Networks (MANETs) are becoming very attractive and useful in many kinds of communication and networking applications. This is due to their efficiency, relatively low cost, and flexibility provided by their dynamic infrastructure. Performance evaluation of mobile ad hoc networks is needed to compare various architectures of the network for their performance, study the effect of varying certain network parameters and study the interaction between various parameters that characterise the network. It can help in the design and implementation of MANETs. It is to be noted that most of the research that studies the performance of MANETs were evaluated using discrete event simulation (DES) utilising a broad band of network simulators. The principle drawback of DES models is the time and resources needed to run such models for large realistic systems, especially when results with a high accuracy are desired. In addition, studying typical problems such as the deadlock and concurrency in MANETs using DES is hard because network simulators implement the network at a low abstraction level and cannot support specifications at higher levels. Due to the advantage of quick construction and numerical analysis, analytical modelling techniques, such as stochastic Petri nets and process algebra, have been used for performance analysis of communication systems. In addition, analytical modelling is a less costly and more efficient method. It generally provides the best insight into the effects of various parameters and their interactions. Hence, analytical modelling is the method of choice for a fast and cost effective evaluation of mobile ad hoc networks. To the best of our knowledge, there is no analytical study that analyses the performance of multi-hop ad hoc networks, where mobile nodes move according to a random mobility model, in terms of the end-to-end delay and throughput. This work ii presents a novel analytical framework developed using stochastic reward nets and mathematical modelling techniques for modelling and analysis of multi-hop ad hoc networks, based on the IEEE 802.11 DCF MAC protocol, where mobile nodes move according to the random waypoint mobility model. The proposed framework is used to analysis the performance of multi-hop ad hoc networks as a function of network parameters such as the transmission range, carrier sensing range, interference range, number of nodes, network area size, packet size, and packet generation rate. The proposed framework is organized into several models to break up the complexity of modelling the complete network and make it easier to analyse each model as required. This is based on the idea of decomposition and fixed point iteration of stochastic reward nets. The proposed framework consists of a mathematical model and four stochastic reward nets models; the path analysis model, data link layer model, network layer model and transport layer model. These models are arranged in a way similar to the layers of the OSI protocol stack model. The mathematical model is used to compute the expected number of hops between any source-destination pair; and the average number of carrier sensing, hidden, and interfering nodes. The path analysis model analyses the dynamic of paths in the network due to the node mobility in terms of the path connection availability and rate of failure and repair. The data link layer model describes the behaviour of the IEEE 802.11 DCF MAC protocol. The actions in the network layer are modelled by the network layer model. The transport layer model represents the behaviour of the transport layer protocols. The proposed models are validated using extensive simulations

Performance evaluation of a communication network

This work uses a simulation package to analyze the performance of a specific X.25 Value Added Communication Network (VAN), comprising a Network Administrator and a cluster of Network Concentrators (NCs). Detailed models of the network elements are developed, and system performance is analyzed in terms of network response time for the terminal users communicating across the network, identification of areas of bottlenecks in the NC system, and NC system throughput. The througput parameter is represented by the percentage of the output traffic to the load offered from the network of terminals. The performance of the Network Administrator system is also modeled, focusing particularly on the automatic restoration of service to failed NCs through downloading of operating software sets over the X.25 network. The final part consists of a model of a modification of the network manager components of the network as proposed in the DM upgrade project. In this section, NC loading time is again the desired performance indicator. It is shown that there is no noticeable improvement in this parameter between the original system and the proposed upgrade, both systems having a minimum loading time of about 3.5 to 6 minutes for a small network

Bayesian Prognostic Framework for High-Availability Clusters

Critical services from domains as diverse as finance, manufacturing and healthcare are often delivered by complex enterprise applications (EAs). High-availability clusters (HACs) are software-managed IT infrastructures that enable these EAs to operate with minimum downtime. To that end, HACs monitor the health of EA layers (e.g., application servers and databases) and resources (i.e., components), and attempt to reinitialise or restart failed resources swiftly. When this is unsuccessful, HACs try to failover (i.e., relocate) the resource group to which the failed resource belongs to another server. If the resource group failover is also unsuccessful, or when a system-wide critical failure occurs, HACs initiate a complete system failover. Despite the availability of multiple commercial and open-source HAC solutions, these HACs (i) disregard important sources of historical and runtime information, and (ii) have limited reasoning capabilities. Therefore, they may conservatively perform unnecessary resource group or system failovers or delay justified failovers for longer than necessary. This thesis introduces the first HAC taxonomy, uses it to carry out an extensive survey of current HAC solutions, and develops a novel Bayesian prognostic (BP) framework that addresses the significant HAC limitations that are mentioned above and are identified by the survey. The BP framework comprises four \emph{modules}. The first module is a technique for modelling high availability using a combination of established and new HAC characteristics. The second is a suite of methods for obtaining and maintaining the information required by the other modules. The third is a HAC-independent Bayesian decision network (BDN) that predicts whether resource failures can be managed locally (i.e., without failovers). The fourth is a method for constructing a HAC-specific Bayesian network for the fast prediction of resource group and system failures. Used together, these modules reduce the downtime of HAC-protected EAs significantly. The experiments presented in this thesis show that the BP framework can deliver downtimes between 5.5 and 7.9 times smaller than those obtained with an established open-source HAC

A Dual-Mode Adaptive MAC Protocol for Process Control in Industrial Wireless Sensor Networks

Doktorgradsavhandling ved Fakultet for teknologi og realfag, Universitetet i Agder, 2017Wireless Sensor Networks (WSNs) consist of sensors and actuators operating together to provide monitoring and control services. These services are used in versatile applications ranging from environmental monitoring t oindustrial automation applications. Industrial Wireless Sensor Network (IWSN) is a sub domain of the WSN domain, focussing the industrial monitoring and automation applications. The IWSN domain differs from the generic WSN domains in terms of its requirements. General IWSN requirements include: energy efficiency and quality of service, and strict requirements are imposed on the quality of service expected by IWSN applications. Quality of service in particular relates to reliability, robustness, and predictability. Medium Access Control (MAC) protocols in an IWSN solution are responsible for managing radio communications, the main consumer of power in every IWSN element. With proper measures, MAC protocols can provide energy efficient solutions along with required quality of service for process control applications. The first goal of the thesis was to assess the possibility of creating a MAC protocol exploiting properties of the application domain, the process control domain. This resulted in the creation of the Dual-Mode Adaptive Medium Access Control Protocol (DMAMAC) which constitutes the main contribution of this thesis. The DMAMAC protocol is energy efficient,while preserving real-time requirements, and is robust to packet failure. This has been guaranteed by the thorough evaluation of the protocol via simulation, verification, and implementation with deployment testing. In parallel, we also investigated the possibility of using an alternative development approach for MAC protocols. Specifically, we have proposed a development approach based on MAC protocol model in CPN tools. The development approach consists of automatic code generation for the MiXiM simulation tool and the TinyOS platform. We used the related GinMAC protocol as a running example for the development approach. The generated code for MiXiM simulation platform and the TinyOS implementation platform are evaluated via simulation and deployment respectively. This results in a faster design to implementation time, and closely related protocol artifacts, improving on the traditional approach

Parallel simulation techniques for telecommunication network modelling

In this thesis, we consider the application of parallel simulation to the performance modelling of telecommunication networks. A largely automated approach was first explored using a parallelizing compiler to speed up the simulation of simple models of circuit-switched networks. This yielded reasonable results for relatively little effort compared with other approaches. However, more complex simulation models of packet- and cell-based telecommunication networks, requiring the use of discrete event techniques, need an alternative approach. A critical review of parallel discrete event simulation indicated that a distributed model components approach using conservative or optimistic synchronization would be worth exploring. Experiments were therefore conducted using simulation models of queuing networks and Asynchronous Transfer Mode (ATM) networks to explore the potential speed-up possible using this approach. Specifically, it is shown that these techniques can be used successfully to speed-up the execution of useful telecommunication network simulations. A detailed investigation has demonstrated that conservative synchronization performs very well for applications with good look ahead properties and sufficient message traffic density and, given such properties, will significantly outperform optimistic synchronization. Optimistic synchronization, however, gives reasonable speed-up for models with a wider range of such properties and can be optimized for speed-up and memory usage at run time. Thus, it is confirmed as being more generally applicable particularly as model development is somewhat easier than for conservative synchronization. This has to be balanced against the more difficult task of developing and debugging an optimistic synchronization kernel and the application models

Factories of the Future

Engineering; Industrial engineering; Production engineerin

Methoden und Beschreibungssprachen zur Modellierung und Verifikation vonSchaltungen und Systemen: MBMV 2015 - Tagungsband, Chemnitz, 03. - 04. März 2015

Der Workshop Methoden und Beschreibungssprachen zur Modellierung und Verifikation von Schaltungen und Systemen (MBMV 2015) findet nun schon zum 18. mal statt. Ausrichter sind in diesem Jahr die Professur Schaltkreis- und Systementwurf der Technischen Universität Chemnitz und das Steinbeis-Forschungszentrum Systementwurf und Test. Der Workshop hat es sich zum Ziel gesetzt, neueste Trends, Ergebnisse und aktuelle Probleme auf dem Gebiet der Methoden zur Modellierung und Verifikation sowie der Beschreibungssprachen digitaler, analoger und Mixed-Signal-Schaltungen zu diskutieren. Er soll somit ein Forum zum Ideenaustausch sein. Weiterhin bietet der Workshop eine Plattform für den Austausch zwischen Forschung und Industrie sowie zur Pflege bestehender und zur Knüpfung neuer Kontakte. Jungen Wissenschaftlern erlaubt er, ihre Ideen und Ansätze einem breiten Publikum aus Wissenschaft und Wirtschaft zu präsentieren und im Rahmen der Veranstaltung auch fundiert zu diskutieren. Sein langjähriges Bestehen hat ihn zu einer festen Größe in vielen Veranstaltungskalendern gemacht. Traditionell sind auch die Treffen der ITGFachgruppen an den Workshop angegliedert. In diesem Jahr nutzen zwei im Rahmen der InnoProfile-Transfer-Initiative durch das Bundesministerium für Bildung und Forschung geförderte Projekte den Workshop, um in zwei eigenen Tracks ihre Forschungsergebnisse einem breiten Publikum zu präsentieren. Vertreter der Projekte Generische Plattform für Systemzuverlässigkeit und Verifikation (GPZV) und GINKO - Generische Infrastruktur zur nahtlosen energetischen Kopplung von Elektrofahrzeugen stellen Teile ihrer gegenwärtigen Arbeiten vor. Dies bereichert denWorkshop durch zusätzliche Themenschwerpunkte und bietet eine wertvolle Ergänzung zu den Beiträgen der Autoren. [... aus dem Vorwort

Factories of the Future

Engineering; Industrial engineering; Production engineerin

Security and Energy Efficiency in Resource-Constrained Wireless Multi-hop Networks

In recent decades, there has been a huge improvement and interest from the research community in wireless multi-hop networks. Such networks have widespread applications in civil, commercial and military applications. Paradigms of this type of networks that are critical for many aspects of human lives are mobile ad-hoc networks, sensor networks, which are used for monitoring buildings and large agricultural areas, and vehicular networks with applications in traffic monitoring and regulation. Internet of Things (IoT) is also envisioned as a multi-hop network consisting of small interconnected devices, called ``things", such as smart meters, smart traffic lights, thermostats etc. Wireless multi-hop networks suffer from resource constraints, because all the devices have limited battery, computational power and memory. Battery level of these devices should be preserved in order to ensure reliability and communication across the network. In addition, these devices are not a priori designed to defend against sophisticated adversaries, which may be deployed across the network in order to disrupt network operation. In addition, the distributed nature of this type of networks introduces another limitation to protocol performance in the presence of adversaries. Hence, the inherit nature of this type of networks poses severe limitations on designing and optimizing protocols and network operations. In this dissertation, we focus on proposing novel techniques for designing more resilient protocols to attackers and more energy efficient protocols. In the first part of the dissertation, we investigate the scenario of multiple adversaries deployed across the network, which reduce significantly the network performance. We adopt a component-based and a cross-layer view of network protocols to make protocols secure and resilient to attacks and to utilize our techniques across existing network protocols. We use the notion of trust between network entities to propose lightweight defense mechanisms, which also satisfy performance requirements. Using cryptographic primitives in our network scenario can introduce significant computational overhead. In addition, behavioral aspects of entities are not captured by cryptographic primitives. Hence, trust metrics provide an efficient security metric in these scenarios, which can be utilized to introduce lightweight defense mechanisms applicable to deployed network protocols. In the second part of the dissertation, we focus on energy efficiency considerations in this type of networks. Our motivation for this work is to extend network lifetime, but at the same time maintain critical performance requirements. We propose a distributed sleep management framework for heterogeneous machine-to-machine networks and two novel energy efficient metrics. This framework and the routing metrics are integrated into existing routing protocols for machine-to-machine networks. We demonstrate the efficiency of our approach in terms of increasing network lifetime and maintaining packet delivery ratio. Furthermore, we propose a novel multi-metric energy efficient routing protocol for dynamic networks (i.e. mobile ad-hoc networks) and illustrate its performance in terms of network lifetime. Finally, we investigate the energy-aware sensor coverage problem and we propose a novel game theoretic approach to capture the tradeoff between sensor coverage efficiency and energy consumption