Wireless sensor networks (WSNs) are now widely used in many applications. Connected Dominating Set (CDS) based routing which is one kind of hierarchical methods has received more attention to reduce routing overhead. The concept of k-connected m-dominating sets (kmCDS) is used to provide fault tolerance and routing flexibility. In this thesis, we first consider how to construct a CDS in WSNs. After that, centralized and distributed algorithms are proposed to construct a kmCDS. Moreover, we introduce some basic ideas of how to use CDS in other potential applications such as partial coverage and data dissemination in WSNs.

The multifaceted utilization of mobile computing devices, including smart phones, PDAs, tablet computers with increasing functionalities and the advances in wireless technologies, has fueled the utilization of collaborative computing (peer-to-peer) technique in mobile environment. Mobile collaborative computing, known as mobile peer-to-peer (MP2P), can provide an economic way of data access among users of diversified applications in our daily life (exchanging traffic condition in a busy high way, sharing price-sensitive financial information, getting the most-recent news), in national security (exchanging information and collaborating to uproot a terror network, communicating in a hostile battle field) and in natural catastrophe (seamless rescue operation in a collapsed and disaster torn area). Nonetheless, data/content dissemination among the mobile devices is the fundamental building block for all the applications in this paradigm. The objective of this research is to propose a data dissemination scheme for mobile distributed systems using an MP2P technique, which maximizes the number of required objects distributed among users and minimizes to object acquisition time. In specific, we introduce a new paradigm of information dissemination in MP2P networks. To accommodate mobility and bandwidth constraints, objects are segmented into smaller pieces for efficient information exchange. Since it is difficult for a node to know the content of every other node in the network, we propose a novel Spatial-Popularity based Information Diffusion (SPID) scheme that determines urgency of contents based on the spatial demand of mobile users and disseminates content accordingly. The segmentation policy and the dissemination scheme can reduce content acquisition time for each node. Further, to facilitate efficient scheduling of information transmission from every node in the wireless mobile networks, we modify and apply the distributed maximal independent set (MIS) algorithm. We also consider neighbor overlap for closely located mobile stations to reduce duplicate transmission to common neighbors. Different parameters in the system such as node density, scheduling among neighboring nodes, mobility pattern, and node speed have a tremendous impact on data diffusion in an MP2P environment. We have developed analytical models for our proposed scheme for object diffusion time/delay in a wireless mobile network to apprehend the interrelationship among these different parameters. In specific, we present the analytical model of object propagation in mobile networks as a function of node densities, radio range, and node speed. In the analysis, we calculate the probabilities of transmitting a single object from one node to multiple nodes using the epidemic model of spread of disease. We also incorporate the impact of node mobility, radio range, and node density in the networks into the analysis. Utilizing these transition probabilities, we construct an analytical model based on the Markov process to estimate the expected delay for diffusing an object to the entire network both for single object and multiple object scenarios. We then calculate the transmission probabilities of multiple objects among the nodes in wireless mobile networks considering network dynamics. Through extensive simulations, we demonstrate that the proposed scheme is efficient for data diffusion in mobile networks.

The multifaceted utilization of mobile computing devices, including smart phones, PDAs, tablet computers with increasing functionalities and the advances in wireless technologies, has fueled the utilization of collaborative computing (peer-to-peer) technique in mobile environment. Mobile collaborative computing, known as mobile peer-to-peer (MP2P), can provide an economic way of data access among users of diversified applications in our daily life (exchanging traffic condition in a busy high way, sharing price-sensitive financial information, getting the most-recent news), in national security (exchanging information and collaborating to uproot a terror network, communicating in a hostile battle field) and in natural catastrophe (seamless rescue operation in a collapsed and disaster torn area). Nonetheless, data/content dissemination among the mobile devices is the fundamental building block for all the applications in this paradigm. The objective of this research is to propose a data dissemination scheme for mobile distributed systems using an MP2P technique, which maximizes the number of required objects distributed among users and minimizes to object acquisition time. In specific, we introduce a new paradigm of information dissemination in MP2P networks. To accommodate mobility and bandwidth constraints, objects are segmented into smaller pieces for efficient information exchange. Since it is difficult for a node to know the content of every other node in the network, we propose a novel Spatial-Popularity based Information Diffusion (SPID) scheme that determines urgency of contents based on the spatial demand of mobile users and disseminates content accordingly. The segmentation policy and the dissemination scheme can reduce content acquisition time for each node. Further, to facilitate efficient scheduling of information transmission from every node in the wireless mobile networks, we modify and apply the distributed maximal independent set (MIS) algorithm. We also consider neighbor overlap for closely located mobile stations to reduce duplicate transmission to common neighbors. Different parameters in the system such as node density, scheduling among neighboring nodes, mobility pattern, and node speed have a tremendous impact on data diffusion in an MP2P environment. We have developed analytical models for our proposed scheme for object diffusion time/delay in a wireless mobile network to apprehend the interrelationship among these different parameters. In specific, we present the analytical model of object propagation in mobile networks as a function of node densities, radio range, and node speed. In the analysis, we calculate the probabilities of transmitting a single object from one node to multiple nodes using the epidemic model of spread of disease. We also incorporate the impact of node mobility, radio range, and node density in the networks into the analysis. Utilizing these transition probabilities, we construct an analytical model based on the Markov process to estimate the expected delay for diffusing an object to the entire network both for single object and multiple object scenarios. We then calculate the transmission probabilities of multiple objects among the nodes in wireless mobile networks considering network dynamics. Through extensive simulations, we demonstrate that the proposed scheme is efficient for data diffusion in mobile networks.

O projeto ISAM apresenta uma plataforma para o desenvolvimento e a execução de aplicações pervasivas. O ambiente de execução proposto na arquitetura ISAM, denominado ISAMpe (ISAM pervasive environment), foi concebido para ser implantado em escala global, com elevado número de componentes. Esses componentes podem ser móveis ou fixos e podem apresentar limitações em seus recursos computacionais. Muitas das aplicações pervasivas que podem ser executadas no ISAMpe têm necessidade de um serviço de disseminação capaz de distribuir informações de um produtor para um grande número de consumidores. Esta dissertação apresenta um serviço de disseminação de informações para a arquitetura ISAM, denominado DIMI (Disseminador Multicast de Informações). O DIMI apresenta uma arquitetura de multicast no nível de aplicação. O DIMI propõe um algoritmo de formação da topologia de disseminação que tem o objetivo de alcançar maior escalabilidade pelo alívio de sobrecarga em participantes específicos do canal, durante os momentos em que houver um grande número de novos consumidores querendo iniciar o consumo simultaneamente. No seu ambiente-alvo, o ISAMpe, o DIMI também oferece suporte à desconexão planejada, permitindo que dispositivos computacionais com limitações de conectividade participem da disseminação, e ainda oferece suporte à mobilidade de usuários. A topologia de comunicação do DIMI adapta-se às condições da rede física subjacente a ela, de acordo com critérios específicos da aplicação que utilizar o serviço. Os resultados obtidos com a simulação de alguns aspectos do funcionamento do DIMI e com a execução do protótipo do mesmo validam os argumentos usados para justificar a necessidade e a forma de construção do serviço. / The ISAM project presents a platform to the development and to the execution of pervasive applications. The execution environment proposed by the ISAM architecture, named ISAMpe (ISAM pervasive environment) was conceived to be deployed on global scale, having a large number of components. These components may be mobile or static and may present computational resource limitations. Many of the pervasive applications that may be executed on the ISAMpe need a dissemination service capable of distribute information from one producer to many consumers. This dissertation presents a information dissemination service for the ISAM architecture, named DIMI (Multicast Information Disseminator - Disseminador Multicast de Informações). DIMI presents an application-level multicast architecture. DIMI proposes an algorithm to create the dissemination topology which objective is to achieve scalability through the relief of overload on specific participants of the channel, during the moments where many new consumers want to start consumption simultaneously. Inside its target-environment, DIMI also offer support to user mobility and to planned disconnection, allowing resource limited computational devices to be participants of the dissemination. DIMI's dissemination topology adapt itself to the conditions of fabric network, accordingly to applications' criteria. The results obtained with the simulation of some DIMI's characteristics and with prototipation validate the arguments used to justify the necessity and the way of construction of the service.

Diferentes organizações públicas e privadas coletam e disponibilizam uma massa de dados sobre a realidade sócio-econômica das diferentes nações. Há hoje, da parte do governo brasileiro, um interesse manifesto de divulgar uma gama diferenciada de informações para os mais diversos perfis de usuários. Persiste, contudo, uma série de limitações para uma divulgação mais massiva e democrática, entre elas, a heterogeneidade das fontes de dados, sua dispersão e formato de apresentação pouco amigável. Devido à complexidade inerente à informação geográfica envolvida, que produz incompatibilidade em vários níveis, o intercâmbio de dados em sistemas de informação geográfica não é problema trivial. Para aplicações desenvolvidas para a Web, uma solução são os Web Services que permitem que novas aplicações possam interagir com aquelas que já existem e que sistemas desenvolvidos em plataformas diferentes sejam compatíveis. Neste sentido, o objetivo do trabalho é mostrar as possibilidades de construção de portais usando software livre, a tecnologia dos Web Services e os padrões do Open Geospatial Consortium (OGC) para a disseminação de dados espaciais. Visando avaliar e testar as tecnologias selecionadas e comprovar sua efetividade foi desenvolvido um exemplo de portal de dados sócio-econômicos, compreendendo informações de um servidor local e de servidores remotos. As contribuições do trabalho são a disponibilização de mapas dinâmicos, a geração de mapas através da composição de mapas disponibilizados em servidores remotos e local e o uso do padrão OGC WMC. Analisando o protótipo de portal construído, verifica-se, contudo, que a localização e requisição de Web Services não são tarefas fáceis para um usuário típico da Internet. Nesta direção, os trabalhos futuros no domínio dos portais de informação geográfica poderiam adotar a tecnologia Representational State Transfer (REST). / Several public and private organizations collect and provide a large amount of data on the socio-economic realities of different countries. Governmental Brazilian agencies are showing today clear interest to disseminate a range of different information to several user profiles. However, many limitations to a more massive and democratic dissemination persist, including heterogeneity of data sources, data dispersion and not friendly format of presentation. Due to the inherent complexity involved in the spatial information, which produces conflict on many levels, the exchange of data in geographic information systems is not a trivial problem. For Web-based applications, Web services can be a useful solution, since they enable new applications to interact with those that already exist and also enable compatibility among systems developed in different platforms. This study aims to show the possibilities of developing thematic portals using free software, Web services technology and the Open Geospatial Consortium standards for the dissemination of spatial data. To evaluate and test the proposal, a portal that integrates data from statistical information servers was built. As example, a thematic portal of socio-economic data was developed, integrating data from a local server and data from remote servers. The main contributions of work is the availability of dynamic maps, the generation of maps by the composition of maps available at local and remote servers and use the standard OGC WMC. The portal shows however that the location and application of Web services are not an easy task for typical Internet users. In this direction, future work could adopt the technology REST (Representational State Transfer).

O projeto ISAM apresenta uma plataforma para o desenvolvimento e a execução de aplicações pervasivas. O ambiente de execução proposto na arquitetura ISAM, denominado ISAMpe (ISAM pervasive environment), foi concebido para ser implantado em escala global, com elevado número de componentes. Esses componentes podem ser móveis ou fixos e podem apresentar limitações em seus recursos computacionais. Muitas das aplicações pervasivas que podem ser executadas no ISAMpe têm necessidade de um serviço de disseminação capaz de distribuir informações de um produtor para um grande número de consumidores. Esta dissertação apresenta um serviço de disseminação de informações para a arquitetura ISAM, denominado DIMI (Disseminador Multicast de Informações). O DIMI apresenta uma arquitetura de multicast no nível de aplicação. O DIMI propõe um algoritmo de formação da topologia de disseminação que tem o objetivo de alcançar maior escalabilidade pelo alívio de sobrecarga em participantes específicos do canal, durante os momentos em que houver um grande número de novos consumidores querendo iniciar o consumo simultaneamente. No seu ambiente-alvo, o ISAMpe, o DIMI também oferece suporte à desconexão planejada, permitindo que dispositivos computacionais com limitações de conectividade participem da disseminação, e ainda oferece suporte à mobilidade de usuários. A topologia de comunicação do DIMI adapta-se às condições da rede física subjacente a ela, de acordo com critérios específicos da aplicação que utilizar o serviço. Os resultados obtidos com a simulação de alguns aspectos do funcionamento do DIMI e com a execução do protótipo do mesmo validam os argumentos usados para justificar a necessidade e a forma de construção do serviço. / The ISAM project presents a platform to the development and to the execution of pervasive applications. The execution environment proposed by the ISAM architecture, named ISAMpe (ISAM pervasive environment) was conceived to be deployed on global scale, having a large number of components. These components may be mobile or static and may present computational resource limitations. Many of the pervasive applications that may be executed on the ISAMpe need a dissemination service capable of distribute information from one producer to many consumers. This dissertation presents a information dissemination service for the ISAM architecture, named DIMI (Multicast Information Disseminator - Disseminador Multicast de Informações). DIMI presents an application-level multicast architecture. DIMI proposes an algorithm to create the dissemination topology which objective is to achieve scalability through the relief of overload on specific participants of the channel, during the moments where many new consumers want to start consumption simultaneously. Inside its target-environment, DIMI also offer support to user mobility and to planned disconnection, allowing resource limited computational devices to be participants of the dissemination. DIMI's dissemination topology adapt itself to the conditions of fabric network, accordingly to applications' criteria. The results obtained with the simulation of some DIMI's characteristics and with prototipation validate the arguments used to justify the necessity and the way of construction of the service.

O projeto ISAM apresenta uma plataforma para o desenvolvimento e a execução de aplicações pervasivas. O ambiente de execução proposto na arquitetura ISAM, denominado ISAMpe (ISAM pervasive environment), foi concebido para ser implantado em escala global, com elevado número de componentes. Esses componentes podem ser móveis ou fixos e podem apresentar limitações em seus recursos computacionais. Muitas das aplicações pervasivas que podem ser executadas no ISAMpe têm necessidade de um serviço de disseminação capaz de distribuir informações de um produtor para um grande número de consumidores. Esta dissertação apresenta um serviço de disseminação de informações para a arquitetura ISAM, denominado DIMI (Disseminador Multicast de Informações). O DIMI apresenta uma arquitetura de multicast no nível de aplicação. O DIMI propõe um algoritmo de formação da topologia de disseminação que tem o objetivo de alcançar maior escalabilidade pelo alívio de sobrecarga em participantes específicos do canal, durante os momentos em que houver um grande número de novos consumidores querendo iniciar o consumo simultaneamente. No seu ambiente-alvo, o ISAMpe, o DIMI também oferece suporte à desconexão planejada, permitindo que dispositivos computacionais com limitações de conectividade participem da disseminação, e ainda oferece suporte à mobilidade de usuários. A topologia de comunicação do DIMI adapta-se às condições da rede física subjacente a ela, de acordo com critérios específicos da aplicação que utilizar o serviço. Os resultados obtidos com a simulação de alguns aspectos do funcionamento do DIMI e com a execução do protótipo do mesmo validam os argumentos usados para justificar a necessidade e a forma de construção do serviço. / The ISAM project presents a platform to the development and to the execution of pervasive applications. The execution environment proposed by the ISAM architecture, named ISAMpe (ISAM pervasive environment) was conceived to be deployed on global scale, having a large number of components. These components may be mobile or static and may present computational resource limitations. Many of the pervasive applications that may be executed on the ISAMpe need a dissemination service capable of distribute information from one producer to many consumers. This dissertation presents a information dissemination service for the ISAM architecture, named DIMI (Multicast Information Disseminator - Disseminador Multicast de Informações). DIMI presents an application-level multicast architecture. DIMI proposes an algorithm to create the dissemination topology which objective is to achieve scalability through the relief of overload on specific participants of the channel, during the moments where many new consumers want to start consumption simultaneously. Inside its target-environment, DIMI also offer support to user mobility and to planned disconnection, allowing resource limited computational devices to be participants of the dissemination. DIMI's dissemination topology adapt itself to the conditions of fabric network, accordingly to applications' criteria. The results obtained with the simulation of some DIMI's characteristics and with prototipation validate the arguments used to justify the necessity and the way of construction of the service.

Critical infrastructures like oil & gas, power grids, water treatment facilities, domain name system (DNS) etc., are attractive targets for attackers — both due to the potential impact of attacks on such systems, and due to the enormous attack surface exposed by such systems. Unwarranted functionality in the form of accidental bugs or maliciously inserted hidden functionality in any component of a system could potentially be exploited by attackers to launch attacks on the system. As it is far from practical to root out undesired functionality in every component of a complex system, it is essential to develop security measures for protecting CI systems that rely only on the integrity of a small number of carefully constructed components, identified as the trusted computing base (TCB) for the system. The broad aim of this dissertation is to characterize elements of the TCB for critical infrastructure systems, and outline strategies to leverage the TCB to secure CI systems. A unified provider-middleman-consumer (PMC) view of systems was adopted to characterize systems as being constituted by providers of data, untrusted middlemen, and consumers of data. As the goal of proposed approach is to eliminate the need to trust most components of a system to be secured, most components of the system are considered to fall under the category of “untrusted middlemen.” From this perspective, the TCB for the system is a minimal set of trusted functionality required to verify that the tasks performed by the middle-men will not result in violation of the desired assurances. Specific systems that were investigated in this dissertation work to characterize the minimal TCB included the domain name system (DNS), dynamic DNS, and Supervisory Control and Data Acquisition (SCADA) systems that monitor/control various CI systems. For such systems, this dissertation provides a comprehensive functional specification of the TCB, and outlines security protocols that leverage the trust in TCB functionality to realize the desired assurances regarding the system.

Wireless Sensor Networks (WSNs) continue to evolve as new applications emerge. In the recent past, WSNs were mostly single sink networks with a few number of homogeneous and static sensor nodes. Now, several applications require networks with multiple and moving sinks and targets as well as thousands of heterogeneous devices. However, the same constraints remain: sensor nodes continue to be very limited in resources, posing new challenges in the design of scalable and energy-efficient algorithms and communication protocols to support these new applications. This dissertation first addresses the problem of sink localization in large scale WSNs. A scalable and energy-efficient sink localization mechanism, called the Anchor Location Service (ALS), is introduced to support the use of location-based routing protocols. ALS avoids frequent and costly flooding procedures derived from the mobility of the sinks and targets, and utilizes face routing to guarantee the success of localization. The problem of topology control in heterogeneous environments is addressed next. A new topology control mechanism, the Residual Energy-Aware Dynamic (READ) algorithm, is devised to extend the lifetime of the network while maintaining connectivity. READ extends the lifetime of the network by assigning a more prominent role to more powerful devices. ALS and READ are evaluated and compared with other well-known protocols using analytical means and simulations. Results show that ALS provides a scalable sink location service and reduces the communication overhead in scenarios with multiple and moving sinks and targets. Results also show that READ increases both the network lifetime and the packet delivery rate.

Cette thèse traite la problématique de la dissémination et l’agrégation des données dans un contexte de réseaux VANET (Vehicle Ad-Hoc Networks). Cette problématique est fort intéressante, toujours d’actualité dans un monde de plus en plus urbanisé. En effet, d’un côté la dissémination permet d’informer les véhicules mobiles des principaux événements en temps utile, et de l’autre côté l’agrégation permet de résumer plusieurs données émanant de sources différentes concernant le même événement. Le challenge de la dissémination consiste à calculer la zone de relevance d’un événement, de délivrer les messages aux véhicules de cette zone, et de continuer à délivrer les messages en continu aux véhicules de cette zone. Le challenge de l’agrégation consiste essentiellement à sélectionner les messages à agréger et à qualifier les messages provenant de véhicules lointains. Pour résoudre le problème de dissémination nous proposons un nouveau protocole de dissémination des données dans les réseaux VANET. La principale idée de ce protocole est basée sur la définition de zones de relevance ZOR (zone of relevance of a région) pour la mesure de l’intérêt d’une zone par rapport à un évènement donné, et la définition de split Map permettant de décomposer une grande région en un ensemble de ZORs. L’approche de calcul des ZORs est formalisée, elle est basée sur les techniques de greedy pour l’extraction de la couverture pertinente. Le protocole de dissémination présenté sous forme de diagramme Flowchart qui résumé les activités lorsque qu’un véhicule est en mouvement, un événement est détecté. La performance du protocole proposé est évaluée et comparé au protocole Slotted1-Persistence à travers un environnement de simulations et une topologie réelle de routes de la ville de Bizerte en Tunisie. Les résultats de simulation sont présentés et discutés.D’autre part, certaines applications VANET, par exemple le système d’information de trafic (TIS), nécessitent une agrégation de données pour informer les véhicules des conditions de circulation, ce qui réduit les embouteillages et par conséquent les émissions de CO2 Par conséquent, la conception d'un protocole d'agrégation efficace combinant des informations de trafic corrélées telles que l'emplacement, la vitesse et la direction, appelées données flottantes sur les voitures (FCD), pose un problème complexe. Dans cette thèse, nous introduisons un nouveau protocole d’agrégation de données dans un réseau VANET appelé SDDA (Smart Directional Data Aggregation). Ce protocole est dédié aussi bien à l’échange de données dans un contexte urbain et autoroutier. Le protocole proposé est basé sur une sélection des messages à agréger. Trois principaux filtres ont été utilisés : filtrage basé sur la direction des véhicules, filtrage basé sur la limitation de vitesse, et filtrage basé sur l’élimination des messages dupliqués. Trois algorithmes d’agrégation sont proposés, ils visent à optimiser l’algorithme de SOTIS. Les trois algorithmes traitent des cas de routes unidirectionnelles, bidirectionnelles et les réseaux urbains. A l’image du chapitre précédent, la performance des algorithmes proposés sont évaluées à travail un travail de simulation et différents résultats sont présentés et discutés. / Since the last decade, the emergence of affordable wireless devices in vehicle ad-hoc networks has been a key step towards improving road safety as well as transport efficiency. Informing vehicles about interesting safety and non-safety events is of key interest. Thus, the design of an efficient data dissemination protocol has been of paramount importance. A careful scrutiny of the pioneering vehicle-to-vehicle data dissemination approaches highlights that geocasting is the most feasible approach for VANET applications, more especially in safety applications, since safety events are of interest mainly to vehicles located within a specific area, commonly called ZOR or Zone Of Relevance, close to the event. Indeed, the most challenging issue in geocast protocols is the definition of the ZOR for a given event dissemination. In this thesis, our first contribution introduces a new geocast approach, called Data Dissemination Protocol based on Map Splitting(DPMS). The main thrust of DPMS consists of building the zones of relevance through the mining of correlations between vehicles’ trajectories and crossed regions. To do so, we rely on the Formal Concept Analysis (FCA), which is a method of extracting interesting clusters from relational data. The performed experiments show that DPMS outperforms its competitors in terms of effectiveness and efficiency. In another hand, some VANET applications, e.g., Traffic Information System (TIS), require data aggregation in order to inform vehicles about road traffic conditions, which leads to reduce traffic jams and consequently CO2 emission while increasing the user comfort. Therefore, the design of an efficient aggregation protocol that combines correlated traffic information like location, speed and direction known as Floating Car Data (FCD) is a challenging issue. In this thesis, we introduce a new TIS data aggregation protocol called Smart Directional Data Aggregation (SDDA) able to decrease the network overload while obtaining high accurate information on traffic conditions for large road sections. To this end, we introduce three levels of messages filtering: (i) filtering all FCD messages before the aggregation process based on vehicle directions and road speed limitations, (ii) integrating a suppression technique in the phase of information gathering in order to eliminate the duplicate data, and (iii) aggregating the filtered FCD data and then disseminating it to other vehicles. The performed experiments show that the SDDA outperforms existing approaches in terms of effectiveness and efficiency.