Les systèmes de communication modernes sont caractérisés par leur besoin croissant en mécanismes d’auto-configuration. En effet, dans de nombreux cas pratiques, la présence de dispositifs de centralisation tel qu’une station de base n’est ni réaliste ni pratique. Ceci est le cas, par exemple, des situations militaires ou aussi celles d’urgence, ou lorsque le déploiement de plus en plus dense de points d’accès rend la planification humaine irréalisable. Par conséquent, des problèmes tel que la conception de règles de comportement pour les appareils (ou groupes d’appareils) sur la fa¸ con de choisir leurs propres paramètres de transmission, se présentent naturellement. En particulier, les algorithmes d’auto-configuration doivent être en mesure de répondre à la nécessité de détecter, d’éviter ou de réduire les interférences, maintenant ainsi une qualité suffisante de communications quand une centralisation est indisponible, et ceci avec un minimum d’échange d’informations et de coopération. En outre, ces algorithmes doivent être en mesure de faire face aux variations naturelles des conditions d’émission, en raison de l’atténuation, des effets de masque, de la mobilité et de la variation des comportements des autres dispositifs qui peuvent éventuellement créer des interférences supplémentaires. L’objectif de cette thèse est d’étudier le problème conjoint de sélection de canal et de contrôle de puissance dans le contexte de réseaux ad hoc clustérisés à canaux multiples, c’est à dire, des réseaux décentralisés dans lesquels les appareils radio sont disposés en groupes appelés clusters, et de proposer un algorithme d’auto-configuration décentralisé viable pour un tel réseau.Le réseau est étudié et analysé par l’intermédiaire de la théorie des jeux, et les équilibres relatifs sont identifiés. Le premier objectif consiste à utiliser ces équilibres afin de quantifier les performances des différents algorithmes qui proviennent de la théorie de l’apprentissage dans les jeux. Un algorithme basé sur le paradigme “trial and error” est alors sélectionné en tant que solution candidat. Une fonction d’utilité particulière est conçue afin que l’équilibre puisse coïncider avec les solutions d’ un problème d’optimisation, maximisant ainsi la qualité des communications, tout en minimisant les ressources nécessaires. Ces résultats sont présentés sous la forme la plus générale et, par conséquent, ils peuvent ˆ être aussi considérés comme un cadre théorique général pour la conception des jeux, ainsi que des algorithmes d’apprentissage avec lesquels les réseaux décentralisés peuvent fonctionner à des points optimaux globaux, et ceci à l’aide uniquement de leurs connaissances locales disponibles. La pertinence de la conception du jeu ainsi que de l’algorithme d’apprentissage est mis en évidence au moyen de scénarios spécifiques dans des réseaux ad hoc clustérisés et décentralisés. Les résultats numériques confirment la pertinence de l’utilisation des fonctions utilitaires appropriées ainsi que de l’apprentissage ”trial and error” dans l’amélioration de la performance des réseaux décentralisés. / Modern communication systems are characterized by an increasing need for self-configuring networks. In fact, in many practical cases, the presence of centralizing devices such as a base station is neither realistic nor practical. This is the case, for instance, in military or emergency situation, or when the increasingly dense deployment of access points makes a man-made planning unfeasible. As a consequence, problems like designing behavioral rules for devices (or groups of devices) on how to select their own transmit parameters naturally arise. In particular, self-configuring algorithms must be able to respond to the necessity of detecting, avoiding or reducing interference, thus maintaining a sufficient quality of the communications when no centralization is available, and with minimum information exchange and cooperation. Moreover, these algorithms must be able to cope with the variations of the transmission conditions due to fading, shadowing, mobility and to the change in other devices behavioral patterns eventually creating extra interference.The goal of this thesis is to study the joint problem of channel selection and power control in the context of multiple-channel clustered ad-hoc networks, i.e., decentralized networks in which radio devices are arranged into groups known as clusters, and to propose a viable decentralized self-configuring algorithm for such a network.The network is studied and analyzed through game theory, and the relative equilibria are identified. The first purpose is to use these equilibria in order to quantify the performance of different algorithms that originate from the theory of learning in games. An algorithm based on the trial and error paradigm is then selected as a candidate solution. A particular utility function is designed in order for the equilibria to coincide with the solutions of an optimization problem, thus maximizing the quality of the communications while minimizing the resources needed. These results are presented in the most general form and therefore, they can also be seen as a framework for designing both games and learning algorithms with which decentralized networks can operate atglobal optimal points using only their available local knowledge. The pertinence of the game design and the learning algorithm are highlighted using specific scenarios in decentralized clustered ad hoc networks. Numerical results confirm the relevance of using appropriate utility functions and trial and error learning for enhancing the performance of decentralized networks.

Um dos grandes avanços na área da computação nas últimas décadas refere-se aos sistemas distribuídos. O uso de tais sistemas tem crescido vertiginosamente nos últimos anos. Com o surgimento e uso de tecnologias de redes sem-fio, os sistemas ganharam mobilidade e dinamismo. Pessoas podem entrar ou sair de seus locais de trabalho, de entretenimento ou mesmo de suas casas com seus computadores móveis; redes podem ser formadas ou extintas conforme a dinâmica de um grupo de pessoas; e novos serviços podem ser disponibilizados ou interrompidos. Em sistemas como tais, um sistema de localização de serviços automático é fundamental para acompanhar as contínuas modificações na rede. A localização de serviços permite que, em uma rede de endereçamento estático ou dinâmico, dispositivos e serviços possam ser encontrados de modo completamente automático. A presente dissertação propõe um sistema de localização lógica (endereçamento) de serviços e dispositivos em uma rede local ou geograficamente distribuída, indo ao encontro às necessidades de controle de sistemas distribuídos dinâmicos, contribuindo ao mesmo tempo com questões de usabilidade e configuração automática de redes. O sistema, também, busca resolver questões relacionadas ao uso dos serviços entre redes protegidas por firewalls ou que utilizam configurações de NAT. / In the last decades, one of the most important progresses in computation is related to the distributed systems. The usage of these systems has increased a lot, in the last years. Due the emergence of wireless technologies, systems have acquired mobility and dynamism. People can enter or leave places, such as home, workplaces and entertainment spots, caring their mobile computers; networks can be formed or extinguished in accordance with the people dynamism; and new services can be available or interrupted. At these systems, a service location system is needed to keep track of the unceasing modifications in the network. The service location enables that services and devices can be found, at dynamic or static networks. This master thesis proposes a system for location of the logical addresses of services and devices at local or wide area networks. This work contributes to issues related to distributed systems control, usability and automatic network configuration. This system also solves questions related to service usage between networks using firewalls or NAT. Besides that, other points related to network interconnections in distributed systems, for example, using the Internet, are raised and solved.

Este trabalho estuda a implementação do sistema de Quorum associado ao algoritmo epidêmico Gossip, a implementação de um novo algoritmo de economia de energia - o PWSave - e o protocolo de roteamento AODV em um cenário com e sem falhas de uma rede ad hoc com mobilidade. Optou-se por implementar este trabalho em um ambiente de simulação, dado que a modelagem matemática da associação do Gossip, Quorum e PWSave com os 80 nós - quantidade de nós escolhida para o ambiente de simulação - apresentaria maior complexidade e demora ao abranger todas as variáveis de ambiente desse conjunto de soluções para cada nó presente na rede. A rotina de programação - com o uso de loops para os trabalhos repetitivos - presente no ambiente de simulação permite que os experimentos sejam efetuados mais rapidamente e com menor probabilidade de erros. Os estudos [1], [2] demonstraram, respectivamente, que soluções abrangendo o algoritmo epidêmico Gossip e o sistema de compartilhamento de dados Quorum apresentam resultados favoráveis para uma rede ad hoc com alta mobilidade. Em [1] é apresentado um cenário muito próximo ao implementado neste trabalho, com a utilização do algoritmo Gossip ao protocolo de roteamento Ad-Hoc On-Demand Distance Vector (AODV). Os parâmetros analisados foram os mesmos, a saber: routes requests (RREQ), perda de pacote, vazão e latência. Os resultados do cenário simulado mostram uma diminuição no número de RREQs em uma rede ad hoc, e os demais parâmetros, medidos no ambiente de simulação, são pouco afetados. De acordo com [2] constata-se que há um aumento da resiliência e da vazão da rede e uma menor sobrecarga causada pela distribuição da informação na rede ad hoc pelo sistema de Quorum. A associação do algoritmo Gossip com o sistema de Quorum resultou em uma diminuição considerável de RREQs e perda de pacotes, mas o parâmetro de consumo de energia, que deve ser um fator importante em uma rede ad hoc e/ou uma rede sensor, não apresentou nenhuma melhora. Portanto, foi implementada uma solução adicional ao Gossip e ao Quorum, com o desenvolvimento de um novo algoritmo de economia de energia denominado de PWSave, no simulador Glomosim com o protocolo de roteamento AODV. O PWSave é responsável pelo adormecimento dos nós da rede que não estejam processando informações, ou seja, os nós, no momento do adormecimento, não poderão trocar dados ou auxiliar na formação de rotas da rede. O PWSave associado ao Gossip e ao sistema de Quorum apresenta resultados que refletem ma diminuição no consumo de energia próxima a 10% em comparação com a solução da associação do Gossip com o sistema de Quorum sem a implementação de PWSave. Os resultados da simulação mostram que a associação de Gossip, Quorum e PWSave acarreta uma redução no número de RREQs e na taxa de perda de pacotes sem degradar muito características de fluxo e latência, além de propiciar uma considerável economia no consumo de energia. / This work studies the implementation of the Quorum system associated with the Gossip algorithm, the implementation of a new power saving algorithm - the PWSave - and the routing protocol AODV in a scenario with and without failures of an ad hoc network with mobility. It has been chosen to implement this work in an environment of simulation, because the mathematical modeling of the association of Gossip, Quorum and PWSave with 80 nodes - number of nodes that has been chosen for the simulation environment - would present a higher complexity and delay to address all environment variables of the solutions set for each node present in the network. The programming routine - with the use of loops for the repetitive works - present in the simulation environment allows the experiments to be performed faster and with less probability of errors. The studies [1], [2] have shown, respectively, that solutions covering the Gossip epidemic algorithm and the system for sharing data Quorum show favorable results for an ad hoc network with high mobility. In [1] is presented a scenario very close to that implemented in this work, using the Gossip algorithm associated to the routing protocol Ad-Hoc On-Demand Distance Vector (AODV). The parameters analyzed were the same: routes requests (RREQ), packet loss, throughput and latency. The simulated scenario results show a decrease in the number of RREQs in an ad hoc network, and the other parameters, measured in the simulation environment, are little afected. According to [2] it is noted that there is an increase in the resilience and throughput of the network and a lower overload caused by the distribution of the information in the ad hoc network by the Quorum system. The association of the Gossip algorithm with the Quorum system resulted in a considerable decrease of RREQs and packet loss, but the parameter of energy consumption, which is an important factor in an ad hoc network and/or a sensor network, shows no improvement. Therefore, an additional solution was associated to the Gossip and to the Quorum, with the development of a new power saving algorithm named PWSave, in the simulator Glomosim with the routing protocol AODV. The PWSave is responsable for the sleeping state of the network nodes when they are not processing information: the nodes at the time of sleep cannot exchange data or assist in the building of network routes. The PWSave associated with the Gossip and Quorum system provides a decrease of the energy consumption close to 10% compared to the association solution of the Gossip with the Quorum system without the PWSave implementation. The results of simulation show that the association of the Gossip, Quorum and PWSave produces a reduction in the number of RREQs and in the rate of packets loss without degrading much the throughput and latency characteristics, providing a considerable energy consumption economy.

Les réseaux sans fil multi-sauts ad hoc et les réseaux de capteurs présentent une solution prometteuse pour assurer une connectivité quasi-permanente dans l'Internet du Futur. Cette connectivité, néanmoins, nécessite la conception d'un protocole d'accès au canal radio fiable, ce qui défi les caractéristiques hostiles et instables des réseaux ad hoc et des réseaux de capteurs. Cet environnement, en effet, est caractérisé par la rareté des ressources radio disponibles, la perte de la bande passante due aux collisions et aux interférences. La nécessité de garantir une meilleure qualité de service aux couches applicatives a promu la conception des protocoles MAC basés sur la technique d'accès TDMA. Essayant de contourner la contrainte d’une fine synchronisation horloge imposée par ce type de protocoles, les recherches se sont orientées vers une conception de protocoles MAC basés sur la technique TDMA dont la taille de la trame est fixe. Cependant, cette conception présente deux principaux inconvénients: d'une part elle procure une inflexibilité quant à la variation de la topologie du réseau suite aux mouvements des nœuds. D'une autre part, elle soulève un problème de dimensionnement : si la taille de la trame est surdimensionnée par rapport au nombre de nœuds présents dans le réseau, des slots non alloués apparaissent induisant la perte de la bande passante. Toutefois, si la taille de la trame est sous-dimensionnée, un risque de famine surgit. Les protocoles MAC basés sur la technique TDMA à taille de trame dynamique présentent une alternative, qui réussit à augmenter le débit au détriment d’une non-équité entre les nœuds dans le réseau. Outre l'utilisation optimale et équitable de la bande passante disponible, la réduction de la consommation d'énergie constitue un autre défi majeur pour les réseaux ad hoc et les réseaux de capteurs. Dans ce travail, deux contributions nommées OSTR et S-OSTR, sont conçues pour améliorer le débit, l'équité et la réduction de la consommation d'énergie dans l'environnement des réseaux ad hoc et des réseaux de capteurs. L'idée motrice d'OSTR consiste à augmenter la taille de la trame TDMA dynamiquement de manière à aboutir à une taille de trame réduite. Dans ce but, OSTR met en place une augmentation à la demande de la taille de la trame. Cette augmentation est établie slot par slot. OSTR se base sur une réutilisation spatiale des times slots ; i.e. un même slot peut être utilisé au même moment par plusieurs nœuds dans le réseau. Afin de prévenir les collisions dues à la coexistence de plusieurs tailles de trames au même temps dans le réseau, OSTR déploie une solution coopérative qui consiste à fixer un rendez-vous au moment duquel la taille de la trame est augmentée simultanément par tous les nœuds dans le réseau. S-OSTR constitue une adaptation du protocole OSTR à l'environnement des réseaux de capteurs. S-OSTR vise à augmenter la durée de vie du réseau. Il déploie ainsi une période d'activité dynamique qui consiste en une trame TDMA augmentant slot-par-slot. S-OSTR effectue également un ordonnancement des activités des nœuds afin de prolonger la période d'inactivité, et par suite prolonger la durée de vie du réseau. Nos deux contributions se basent sur une nouvelle technique d'augmentation dynamique de la taille de la trame TDMA qui consiste à augmenter la taille slot-par-slot. Cette technique permet d'atteindre une taille réduite, et par conséquent d’améliorer l'utilisation de la bande passante et de minimiser la consommation de l'énergie dans le réseau. L'analyse des performances d'OSTR et de S-OSTR souligne leurs potentiels pour s'adapter aux exigences des applications en termes de QoS, pour assurer un accès équitable au canal radio, pour réduire la consommation de l'énergie et pour s'adapter aux différents changements de la topologie du réseau / Wireless multi-hop ad hoc and sensor networks provide a promising solution to ensure ubiquitous connectivity for the Future Internet. Good network connectivity requires designing a reliable Medium Access Control (MAC) protocol, which is a challenging task in the ad hoc and sensor environments. The broadcast and shared nature of the wireless channel renders the bandwidth resources limited and expose the transmissions to relatively high collisions and loss rates. The necessity to provide guaranteed Quality of Service (QoS) to the upper layers triggered the design of conflict-free MAC protocols. The TDMA synchronization constraint is basically behind the rush of MAC protocol design based on a fixed frame size. This design shows inflexibility towards network variations and creates a network dimensioning issue that leads to a famine risk in case the network is under-dimensioned, and to a waste of resources, otherwise. Moreover, the alternative dynamic protocols provide more adaptive solutions to network topology variations at the expense of a fair access to the channel. Alongside with the efficient channel usage and the fair medium access, reducing the energy consumption represents another challenge for ad hoc and sensor networks. Solutions like node activity scheduling tend to increase the network lifetime while fulfilling the application requirements in terms of throughput and delay, for instance. Our contributions, named OSTR and S-OSTR, address the shortcomings of the medium access control protocol design in the challenging environment of wireless multi-hop ad hoc and sensor networks, respectively. For OSTR the idea consists in adopting a dynamic TDMA frame size that increases slot-by-slot according to the nodes arrival/departure to/from the network, and aiming to achieve a minimum frame size. For this end, OSTR couples three major attributes: (1) performing slot-by-slot frame size increase, (2) providing a spatial reuse scheme that favors the reuse of the same slot if possible, (3) and ensuring an on-demand frame size increase only according to the node requirements in terms of throughput. To tackle different frame sizes co-existence in the network, OSTR brings a cooperative solution that consists in fixing an appointment, a date when the frame size in the network is increased. Concerning S-OSTR, it is an amendment of OSTR for wireless sensor networks. It brings the idea of a dynamic active period, since it deploys a dynamic frame size that is built slot-by-slot according to nodes arrival to the network. S-OSTR enforces the slot-by-slot frame size increase by a node activity scheduling to prolong the inactivity period in the network, and hence prolong the overall network lifetime for wireless sensor networks. Our contributions are both based on the new dynamic TDMA frame size increase that consists in increasing the frame size slot-by-slot aiming to achieve a shorter frame size, and hence improve the channel utilization, and reduce the energy consumption. The performance analysis of OSTR and S-OSTR shows that they present good potentials to support QoS requirements, to provide energy-efficiency, to ensure fair medium access, to accommodate network topology changes and finally, to enhance robustness against scalability. The impact of this new TDMA frame size increase technique on the medium access control protocol performance is highlighted through multiple simulations of OSTR and S-OSTR. Multiple comparative studies are also handled to point out the effectiveness of this new technique and the soundness of our contributions

Thesis ( M.Sc. ( Computer Science)) -- University of Limpopo, 2018 / Dynamic spectrum access enabled by cognitive radio networks is envisioned to address the problems of the ever-increasing wireless technology. This innovative technology increases spectrum utility by allowing unlicensed devices to utilise the unused spectrum band of licenced devices opportunistically. The unlicensed devices referred to as secondary users (SUs) constantly sense the spectrum band to avoid interfering with the transmission of the licenced devices known as primary users (PUs).Due to some environmental challenges that can interfere with effective spectrum sensing, the SUs have to cooperate in sensing the spectrum band. However, cooperative spectrum sensing is susceptible to the spectrum sensing data falsification (SSDF) attack where selfish radios falsify the spectrum reports. Hence, there is a need to design a defence scheme that will defend the SSDF attack and guaranty correct final transmission decision. In this study, we proposed the integration of the reputation based system and the qout-of-m rule scheme to defend against the SSDF attack. The reputation-based system was used to determine the trustworthiness of the SUs. The q-out-of-m rule scheme where m sensing reports were selected from the ones with good reputation and q was the final decision, which was used to isolate the entire malicious nodes and make the correct final transmission decision. The proposed scheme was implemented in a Cognitive Radio Ad Hoc Network (CRAHN) where the services of a data fusion centre (FC) were not required. The SUs conducted their own data fusion and made their own final transmission decision based on their sensing reports and the sensing reports of their neighbouring nodes. Matlab was used to implement and simulate the proposed scheme. We compared our proposed scheme with the multifusion based distributed spectrum sensing and density based system schemes. Metrics used were the success probability, missed detection probability and false alarm probability. The proposed scheme performed better compared to the other schemes in all the metrics. / CSIR, NRF and, University of Limpopo research office

This Thesis expands on the current developments of the theory of stochastic diffusion processes of rumours. This is done by advancing the current mathematical characterisation of the solution to the Daley-Kendall model of the simple S-I-R rumour to a physical solution of the sub-population distribution over time of the generalised simple stochastic spreading process in social situations. After discussing stochastic spreading processes in social situations such as the simple epidemic, the simple rumour, the spread of innovations and ad hoc communications networks, it uses the three sub-population simple rumour to develop the theory for the identification of the exact sub-population distribution over time. This is done by identifying the generalised form of the Laplace Transform Characterisation of the solution to the three sub-population single rumour process and the inverse Laplace Transform of this characterisation. In this discussion the concept of the Inter-Changeability Principle is introduced. The general theory is validated for the three population Daley-Kendall Rumour Model and results for the three, five and seven population Daley-Kendall Rumour Models are pre- sented and discussed. The α - p model results for pseudo-Maki-Thompson Models are presented and discussed. In subsequent discussion it presents for the first time a statement of the Threshold Problem for Stochastic Spreading Processes in Social settings as well as stating the associated Threshold Theorem. It also investigates limiting conditions. Aspects of future research resulting from the extension of the three subpopulation model to more than three subpopulations are discussed at the end of the thesis. The computational demands of applying the theory to more than three subpopulations are restrictive; the size of the total population that can be considered at one time is considerably reduced. To retain the ability to compute a large population size, with an increase in the number of possible subpopulations, a possible method of repeated application of the three population solution is identified. This is done through the medium of two competing mutually exclusive rumours. The final discussion occurs on future investigation into the existence of limit values, zero states, cyclic states and absorbing states for the M subpopulation case. The generalisation and inversion of the Laplace Transform as well as the consequential statement of the threshold theorem, derivation of the transition probabilities and discussion of the limiting conditions are significant advances in the theory of rumours and similar social phenomena. / Thesis (Ph.D.) -- University of Adelaide, School of Mathematical Sciences, 2008

<p>I många nätverk antas det att någon form av fix infrastruktur existerar och att nätverkets olika noder kan använda denna för att kommunicera med varandra. I ett ad hoc-nätverk antar man att det inte finns någon fix infrastruktur och att noderna måste använda varandra för att kunna kommunicera. Ett exempel på ett ad hoc-nätverk kan vara bärbara datorer sammankopplade med infraröda länkar under ett möte. När ad hoc-nätverket är mobilt innebär det att noderna rör sig.</p><p>I detta arbete har de tre protokollen Epidemic, GeoMean och GeoMove tillsammans med de två rörelsemodellerna Waypoint och den utökade slumpmässiga vandringen implementerats i en nyskriven simulator för denna typ av nätverk.</p><p>De två Geo-protokollen är nyutvecklade och syftar till att använda geografisk information för att underlätta kommunikationen i denna kategori av nätverk tillsammans med den nya utvidgade slumpmässiga vandringsmodellen.</p> / <p>In many networks, some kind of fix infrastructure is assumed to exist and the nodes of the network can use this infrastructure to communicate with each other. In an ad hoc network one assumes that there don't exist any kind of fix infrastructure and that the nodes must use each other to be able to communicate. One example of an ad hoc network could be laptops connected together with infrared links during a meeting. When an ad hoc network is mobile it implies that the nodes are moving.</p><p>In this work, the three protocols Epidemic, GeoMean and GeoMove together with the two mobility models Waypoint and Extended Random Walk, have been implemented in a newly written simulator for this kind of network.</p><p>The two Geo-protocols are newly developed and aim to use geographical information to aid communication in this category of networks together with the new Extended Random Walk model.</p>

<p>Internet and mobile communications have had a profound effect on today’s society. New services are constantly being deployed, in which an increasing amount of personal data is being processed in return for personally tailored services. Further, the use of electronic surveillance is increasing. There is the risk that honest citizens will have their privacy invaded for “the greater good”. We argue that it is of uttermost importance to retain the individuals’ control over their personal spheres.</p><p>One approach for enhancing the users’ privacy is to deploy technical measures for safeguarding privacy, so-called Privacy-Enhancing Technologies (PETs). This thesis examines a set of PETs for enabling anonymous communication, so-called anonymous overlay networks,which eliminate the processing of personal data altogether by allowing the users act anonymously when communicating in a networked environment.</p><p>This thesis focuses mainly on mobile networks. These are of great interest because on the one hand they lay the groundwork for new innovative applications, but on the other hand they pose numerous novel challenges to privacy. This thesis describes the implementation</p><p>and performance evaluation of mCrowds – an anonymous overlay network for mobile Internet that enables anonymous browsing. It also describes the ongoing investigation on how to design anonymous overlay networks in order to make them suitable for mobile ad hoc</p><p>networks, a required building block for ambient intelligence.</p>

A mobile ad-hoc network (MANET) is a collection of wireless mobile nodes forming a temporary network without the support of any established infrastructure or centralized administration. There are many potential applications based the techniques of MANETs, such as disaster rescue, personal area networking, wireless conference, military applications, etc. MANETs face a number of challenges for designing a scalable routing protocol due to their natural characteristics. Guaranteeing delivery and the capability to handle dynamic connectivity are the most important issues for routing protocols in MANETs. In this dissertation, we will propose four algorithms that address different aspects of routing problems in MANETs. Firstly, in position based routing protocols to design a scalable location management scheme is inherently difficult. Enhanced Scalable Location management Service (EnSLS) is proposed to improve the scalability of existing location management services, and a mathematical model is proposed to compare the performance of the classical location service, GLS, and our protocol, EnSLS. The analytical model shows that EnSLS has better scalability compared with that of GLS. Secondly, virtual backbone routing can reduce communication overhead and speedup the routing process compared with many existing on-demand routing protocols for routing detection. In many studies, Minimum Connected Dominating Set (MCDS) is used to approximate virtual backbones in a unit-disk graph. However finding a MCDS is an NP-hard problem. In the dissertation, we develop two new pure localized protocols for calculating the CDS. One emphasizes forming a small size initial near-optimal CDS via marking process, and the other uses an iterative synchronized method to avoid illegal simultaneously removal of dominating nodes. Our new protocols largely reduce the number of nodes in CDS compared with existing methods. We show the efficiency of our approach through both theoretical analysis and simulation experiments. Finally, using multiple redundant paths for routing is a promising solution. However, selecting an optimal path set is an NP hard problem. We propose the Genetic Fuzzy Multi-path Routing Protocol (GFMRP), which is a multi-path routing protocol based on fuzzy set theory and evolutionary computing.

In this work, we investigate the application of Bayesian filtering techniques such as Kalman Filtering and Particle filtering to the problems of network time synchronization, self-localization and radio-frequency (RF) tomography in wireless networks. Networks of large numbers of small, cheap, mobile wireless devices have shown enormous potential in applications ranging from intrusion detection to environmental monitoring. These applications require the devices to have accurate time and position estimates, however traditional techniques may not be available. Additionally RF tomography offers a new paradigm to sense the network environment and could greatly enhance existing network capabilities. While there are some existing works addressing these problems, they all suffer from limitations. Current time synchronization methods are not energy efficient on small wireless devices with low quality oscillators. Existing localization methods do not consider additional sources of information available to nodes in the network such as measurements from accelerometers or models of the shadowing environment in the network. RF tomography has only been examined briefly in such networks, and current algorithms can not handle node mobility and rely on shadowing models that have not been experimentally verified. We address the time synchronization problem by analyzing the characteristics of the clocks in small wireless devices, developing a model for it, and then applying a Kalman filter to track both clock offset and skew. In our investigation into RF tomography, we present a method using a Kalman filter which jointly estimates and tracks static and dynamic objects in the environment. We also use channel measurements collected from a field test of our RF tomography testbed to compare RF shadowing models. For the localization problem, we present two algorithms incorporating additional information for improved localization: one based on a distributed extended Kalman filter that combines local acceleration measurements with signal strength measurements for improved localization, and another that uses a distributed particle filter to incorporate a model of the channel environment.