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In recent years, Multi-hop Wireless Networks (MHWNs) have experienced an explosion of deployment due to the increasing demand for continuous connectivity regardless of the physical location. Internet predominant transport protocols, i.e. Transmission Control Protocol (TCP), face performance degradation in MHWNs because of the high loss and link failure rates. Several solutions have been proposed which are based on network state estimation or use information from MAC layer (called metrics) in a cross-layer manner to better comprehend the network state. The first part of this thesis provides a survey and comprehensive definition of common metrics from Physical, MAC, Network and Transport layers and thus provides a multi-criteria and hierarchical classification. After that, the effectiveness in reflecting network information of MAC metrics is also investigated in a systematic way by simulating various network situations and measuring the MAC metrics. Thus, the good MAC metric for congestion control which is coupled with the network contention level and the medium induced losses will be found out. From the results of the effectiveness study, new rate control schemes for transport protocols are proposed which adapt efficiently the source bit rate depending on the network condition provided by some MAC metrics. Through an extensive set of simulations, the performance of the proposed rate control schemes in MHWNs is investigated thoroughly with several network situations.

Cognitive radios are currently presented as the solution to the ever-increasing spectrum shortage problem. However, their increased capabilities over traditional radios introduce a new dimension of security threats. Cooperative Spectrum Sensing (CSS) has been proposed as a means to protect cognitive radio networks from the well known security threats: Primary User Emulation (PUE) and Spectrum Sensing Data Falsification (SSDF). I demonstrate a new threat to trust-based CSS protocols, called the Rogue Signal Framing (RSF) intrusion. Rogue signals can be exploited to create the illusion of malicious sensors which leads to the framing of innocent sensors and consequently, their removal from the shared spectrum sensing. Ultimately, with fewer sensors working together, the spectrum sensing is less robust for making correct spectrum access decisions. The simulation experiments illustrate the impact of RSF intrusions which, in severe cases, shows roughly 40\% of sensors removed. To mitigate the RSF intrusion's damage to the network's trust, I introduce a new defense based on community detection from analyzing the network's Received Signal Strength (RSS) diversity. Tests show a 95\% damage reduction in terms of removed sensors from the shared spectrum sensing, thus retaining the benefits of CSS protocols.

In this thesis, we present novel software technology for the analysis of wireless networks, an emerging area of computer science. To address the widely acknowledged lack of formal foundations in this field, probabilistic model checking, a formal method for verification and performance analysis, is used. Contrary to test and simulation, it systematically explores the full state space and therefore allows reasoning about all possible behaviours of a system. This thesis contributes to design, modelling, and analysis of ad-hoc networks and randomised distributed coordination protocols. First, we present a new hybrid approach that effectively combines probabilistic model checking and state-of-the-art models from the simulation community in order to improve the reliability of design and analysis of wireless sensor networks and their protocols. We describe algorithms for the automated generation of models for both analysis methods and their implementation in a tool. Second, we study spatial properties of wireless sensor networks, mainly with respect to Quality of Service and energy properties. Third, we investigate the contention resolution protocol of the networking standard ZigBee. We build a generic stochastic model for this protocol and analyse Quality of Service and energy properties of it. Furthermore, we assess the applicability of different interference models. Fourth, we explore slot allocation protocols, which serve as a bandwidth allocation mechanism for ad-hoc networks. We build a generic model for this class of protocols, study real-world protocols, and optimise protocol parameters with respect to Quality of Service and energy constraints. We combine this with the novel formalisms for wireless communication and interference models, and finally we optimise local (node) and global (network) routing policies. This is the first application of probabilistic model checking both to protocols of the ZigBee standard and protocols for slot allocation.

The aim of this diploma thesis is to analyze, design and create the architecture of the WSageNt system web interface. The main focus of the system will be traffic monitoring and topology control of the network. The work describes basic technologies, design principles and implementation methods.

Le cadre de cette thèse est l'étude des systèmes contrôlés en réseau sans fil (SCRSF) qui utilise la technologie IEEE 802.15.4. Le premier objectif est d'étudier la pertinence de l'utilisation du réseau de type IEEE 802.15.4 pour les SCRSF puis de proposer et d'évaluer des mécanismes pour garantir la Qualité de Service (QdS) offerte par le réseau au système contrôlé. Nous analysons l'utilisation des slots temporels réservés (GTS) dans le cadre des SCRSF et les contraintes qui en découlent. De plus, nous proposons des mécanismes de gestion de la QdS avec priorité aussi bien pour le mode avec balise que pour le mode sans balise du protocole IEEE 802.15.4. Ces propositions ont été validées par des simulations et une partie de manière analytique. Notre deuxième objectif est de concevoir, d'une manière conjointe, les SCRSF pour pouvoir régler en ligne la QdS offerte par le réseau en fonction de la Qualité de Contrôle (QdC) du système contrôlé. Nous proposons des protocoles d'adaptation en ligne de la QdS du réseau qui prennent en compte la QdC du système contrôlé. Ces protocoles ont été validés par simulations et une implémentation réelle de chacun d'eux est proposée / In this thesis, we study wireless networked control systems (WNCS) which use the IEEE 802.15.4 technology. The first objective is to study the pertinence of the use of the IEEE 802.15.4 for the WNCS, then to propose and evaluate QoS management mechanisms which guarantee the Quality of Service (QoS) offered by network to the controlled system. We analyse the use of the guaranteed temporel slots (GTS) for WNCS and in which conditions it is possible. We propose QoS management mechanisms with priority for both the beacon enabled mode and the non-beacon enabled mode of the IEEE 802.15.4 protocol. These proposals are validated through simulations and partially with analytical approach. The second objective is to design the WNCS so that the QoS offered by the network is adated online depending on the Quality of Control (QoC) on the controlled system. We propose QoS online adaptation protocols which take as parameter the QoC of the system. These protocols are validated through simulations and a realistic implementation of them is proposed

Nowadays, Opportunistic Routing (OR) is widely considered to be the most important paradigm for Multi-hop wireless networks (MWNs). It exploits the broadcast nature of wireless medium to propagate information from one point to another within the network. In OR scheme, when a node has new information to share, it rst needs to set its forwarding list which include the IDs and/or any relevant information to its best suited neighboring nodes. This operation is supported by the use of appropriate metrics. Then, it executes a coordination algorithm allowing transmission reliability and high throughput among the next-hop forwarders. In this paper, we provide a comprehensive guide to understand the characteristics and challenges faced in the area of opportunistic routing protocols in MWNs. Moreover, since the planet we live on is largely covered by water, OR protocols have gained much attention during the last decade in real-time aquatic applications, such as oil/chemical spill monitoring, ocean resource management, anti-submarine missions and so on. One of the major problems in Underwater Wireless Sensor Network (UWSNs) is determining an e cient and reliable routing methodology between the source node and the destination node. Therefore, designing e cient and robust routing protocols for UWSNs became an attractive topic for researchers. This paper seeks to address in detail the key factors of underwater sensor network. Furthermore, it calls into question 5 state-of-the-art routing protocols proposed for UWSN: The Depth-Based Routing protocol (DBR), the Energy-E cient Depth-Based Routing protocol (EEDBR), the Hydraulic-pressure-based anycast routing protocol (Hydrocast), the Geographic and opportunistic routing protocol with Depth Adjustment for mobile underwater sensor networks (GEDAR), and the Void- Aware Pressure Routing for underwater sensor networks (VAPR). Finally, it covers the performance of those protocol through the use of the R programming language.

A utilização das redes sem fio nos mais diversos segmentos vem crescendo vertiginosamente nos últimos anos. Aliado ao crescimento da utilização das redes, está a diversificação de aplicações utilizadas por todos os usuários, sejam eles corporativos ou domésticos. Isto tem contribuído significativamente para o desenvolvimento de tecnologias que ofereçam mecanismos de qualidade de serviço, de forma a permitir o uso satisfatório de aplicações como voz e vídeo em tempo real. Este trabalho estuda os efeitos que a existência de tráfego de voz e dados em redes sem fio padrão IEEE 802.11 causa no desempenho da rede e por consequência no desempenho das aplicações. Para realizar este estudo foram executadas simulações baseadas em uma rede sem fio com topologia ad hoc, com variações no número de estações e quantidade de tráfego gerado. Foram simulados os padrões 802.11g e 802.11e com o objetivo de analisar o desempenho dos mecanismos de qualidade de serviço e os benefícios que estes mecanismos geram para a transmissão de tráfego em tempo real em redes sem fio padrão IEEE 802.11. Verificou-se que o padrão IEEE 802.11e apresenta um ganho de desempenho para aplicações de tempo real, porém ele apresenta limitações que devem ser consideradas nos projetos de redes sem fio. / The use of wirelles networks in most various sectors has been growing drastically in past years Allied to the wireless networks use, the diversification of applications and services provided can be directly verified whether by home or corporate users. This alliance contributes significantly to the needs of technology development which offer the quality of service mechanisms, allowing satisfactory use of real-time applications like voice and video This paper studies the effects that coexistent voice and data traffic on a IEEE 802.11 standard wireless network cause in the network performance and, consequently, in the applications performance. To make this study a reality, it was necessary to run simulations of a wireless ad hoc topology network, with variations in the number of workstations and the quantity of generated traffic. The 802.11g and 802.11e standards were used in the simulations with the purpose of analyzing the performance of quality of service mechanisms and the benefits they create for the real-time transmissions in IEEE 802.11 standard wireless networks. It was verified that the IEEE 802.11e standard presents a perfomance gain for the real-time applications, but it has limitations that should be considered in wireless networks design.

A utilização das redes sem fio nos mais diversos segmentos vem crescendo vertiginosamente nos últimos anos. Aliado ao crescimento da utilização das redes, está a diversificação de aplicações utilizadas por todos os usuários, sejam eles corporativos ou domésticos. Isto tem contribuído significativamente para o desenvolvimento de tecnologias que ofereçam mecanismos de qualidade de serviço, de forma a permitir o uso satisfatório de aplicações como voz e vídeo em tempo real. Este trabalho estuda os efeitos que a existência de tráfego de voz e dados em redes sem fio padrão IEEE 802.11 causa no desempenho da rede e por consequência no desempenho das aplicações. Para realizar este estudo foram executadas simulações baseadas em uma rede sem fio com topologia ad hoc, com variações no número de estações e quantidade de tráfego gerado. Foram simulados os padrões 802.11g e 802.11e com o objetivo de analisar o desempenho dos mecanismos de qualidade de serviço e os benefícios que estes mecanismos geram para a transmissão de tráfego em tempo real em redes sem fio padrão IEEE 802.11. Verificou-se que o padrão IEEE 802.11e apresenta um ganho de desempenho para aplicações de tempo real, porém ele apresenta limitações que devem ser consideradas nos projetos de redes sem fio. / The use of wirelles networks in most various sectors has been growing drastically in past years Allied to the wireless networks use, the diversification of applications and services provided can be directly verified whether by home or corporate users. This alliance contributes significantly to the needs of technology development which offer the quality of service mechanisms, allowing satisfactory use of real-time applications like voice and video This paper studies the effects that coexistent voice and data traffic on a IEEE 802.11 standard wireless network cause in the network performance and, consequently, in the applications performance. To make this study a reality, it was necessary to run simulations of a wireless ad hoc topology network, with variations in the number of workstations and the quantity of generated traffic. The 802.11g and 802.11e standards were used in the simulations with the purpose of analyzing the performance of quality of service mechanisms and the benefits they create for the real-time transmissions in IEEE 802.11 standard wireless networks. It was verified that the IEEE 802.11e standard presents a perfomance gain for the real-time applications, but it has limitations that should be considered in wireless networks design.

The increasing popularity of wireless networks over the last years indicates that there will be a demand for communicating devices providing high capacity communication together with QoS requirements. There are two types of wireless networks, infrastructure and Ad Hoc networks. The variation of topology caused by the mobility of hosts in the Ad Hoc networks results in a long latency, large jitter and low throughput. In infrastructure wireless networks, a base station (BS) or an Access Point (AP) is in charge of the data transmission. Therefore, the wireless hop can be considered as another hop of the transmission path. With the rapid growth of wireless traffics, the future wireless network is expected to provide services for heterogeneous data traffics with different quality of service requirements. Most proposed schemes do not have mechanisms to adapt to environment changes. In real situation, bandwidths, error rates, and loss rates of wireless links vary frequently. The QoS issues are very important in modern networks. There are many proposed service models and mechanisms to support QoS in wireline networks. Most of these QoS mechanisms are not suitable for direct application to the wireless network because of the characteristics of wireless communication which includes: 1) high error rates and bursty errors, 2) location-dependent and time-varying wireless channel capacity, 3) scarce bandwidth, 4) user mobility, and 5) power constraints of the mobile hosts. All of these above characteristics make the development of QoS in wireless networks very difficult and challenging. We try to cope with the bandwidth variations caused by the high error rate and bursty errors in wireless links, and the location-dependent and time-varying natures of wireless channel capacity. Furthermore, we expect to utilize the scarce wireless bandwidth more efficiently. In our proposed scheme, the higher priority flow is capable of broadcasting a message to inform the lower priority flows to change their priorities to adapt to environment variations. We will base on the differentiated service model and propose a Wireless Differentiation (WD) scheme for UDP flows and a Wireless Differentiation with Prioritized ACK (WDPA) scheme for connections with TCP flows which provide QoS support for IEEE 802.11b and do not change the basic access mechanism of IEEE 802.11b.