Τα ασύρματα δίκτυα μικροαισθητήρων αποτελούνται από ένα πολύ μεγάλο πλήθος συσκευών που τοποθετούνται σε μία περιοχή ενδιαφέροντος και αυτοοργανώνονται σε ένα αδόμητο δίκτυο, προκειμένου να καταγράψουν/μετρήσουν/παρακολουθήσουν κάποια περιβαλλοντική μετρική ή φαινόμενο και εν συνεχεία να μεταφέρουν τα δεδομένα σε κάποιο κέντρο ελέγχου. Λόγω των πολύ περιορισμένων δυνατοτήτων των συσκευών, ειδικά όσον αφορά την εμβέλεια επικοινωνίας και τα αποθέματα ενέργειας, αλλά και λόγω του πλήθους τους, είναι απαραίτητη η ανάπτυξη νέων αλγορίθμων και πρωτοκόλλων σχεδιασμένων για τα ιδιαίτερα προβλήματα των δικτύων αισθητήρων. Στην παρούσα διατριβή παρουσιάζουμε έρευνα επικεντρωμένη στην ανάπτυξη, προσομοίωση και αξιολόγηση ενεργειακά αποδοτικών αλγορίθμων, δηλαδή βασικός στόχος είναι η ελαχιστοποίηση της κατανάλωσης ενέργειας. Παρά τη ραγδαία εξέλιξη της τεχνολογίας του υλικού το πρόβλημα βελτιστοποίησης της ενέργειας των συσκευών αισθητήρων παραμένει επίκαιρο αφού οι υπάρχουσες και άμεσα διαφαινόμενες λύσεις μέσω υλικού δεν έχουν δώσει ικανοποιητική απάντηση. Επικεντρώνουμε την έρευνά μας σε τρεις βασικές κατευθύνσεις που στοχεύουν στην εξοικονόμηση και βελτιστοποίηση της κατανάλωσης ενέργειας σε διαφορετικά επίπεδα. Κοινός στόχος είναι η μείωση του κόστους επικοινωνίας, μέσω της ανάδειξης καινοτόμων τεχνικών που δίνουν ώθηση στην ανάπτυξη νέων αλγορίθμων. Συγκεκριμένα, διερευνήσαμε τεχνικές κατανεμημένης προσαρμογής της λειτουργίας ενός πρωτοκόλλου όπου χρησιμοποιούμε πληροφορία διαθέσιμη τοπικά σε κάθε κόμβο ώστε με καθαρά τοπικές επιλογές, να βελτιώσουμε τη συνολική συμπε- ριφορά ενός πρωτοκόλλου. Επίσης προτείνουμε τεχνικές τοπικής συλλογής και εκμετάλλευσης περιορισμένης γνώσης των συνθηκών του δικτύου. Με ενεργειακά αποδοτικό τρόπο συλλέγουμε επιπλέον πληροφορία που χρησιμοποιούμε προκειμένου να επιτευχθούν βελτιστοποιήσεις όπως ο σχηματισμός ενεργειακά αποδοτικών, χαμηλής καθυστέρησης και ανθεκτικών σε σφάλματα μονοπατιών για μετάδοση δεδομένων. Ακόμα, διερευνούμε τεχνικές διαχείρισης της κινητικότητας σε περιπτώσεις δικτύων όπου χαρακτηριστικό είναι η κίνηση τόσο του κέντρου ελέγχου όσο και των συσκευών αισθητήρων. Εξετάσαμε μεθόδους διαπέρασης και κάλυψης του δικτύου από κινητά κέντρα ελέγχου που βασίζονται σε πιθανοτική κίνηση που ευνοεί την επίσκεψη κάποιων περιοχών με βάση τοπικά κριτήρια (συχνότητα προηγούμενων επισκέψεων, τοπική πυκνότητα δικτύου). Οι αλγόριθμοι που αναπτύσσουμε βασισμένοι σε αυτές τις τεχνικές λειτουργούν α) σε επίπεδο διαχείρισης της ίδιας της συσκευής, β) σε επίπεδο πρωτοκόλλου δρομολόγησης και γ) συνολικά σε επίπεδο δικτύου, αναδεικνύοντας μακροσκοπική συμπεριφορά από τοπικές αλληλεπιδράσεις. Οι αλγόριθμοι εφαρμόζονται σε περιπτώσεις δικτύων με διαφορές στην πυκνότητα, κατανομή κόμβων, διαθέσιμη ενέργεια αλλά και με ριζικές διαφοροποιήσεις στο μοντέλο αφού εξετάζουμε δίκτυα με παρουσία σφαλμάτων, σταδιακή ανάπτυξη κόμβων ακόμα και με κινούμενους κόμβους. Σε όλες αυτές τις περιπτώσεις οι τεχνικές μας πετυχαίνουν σημαντικά οφέλη γεγονός που αναδεικνύει την αξία τους σαν εργαλεία αλγοριθμικής σχεδίασης. / -

Network protocol construction is a complex and error prone task. The challenges originate both from the inherent complexity of developing correct program code and from the distributed nature of networked systems. Protocol errors can have devastating consequences. Even so, methods for ensuring protocol correctness are currently only used to a limited extent. A central reason for this is that they are often complex and expensive to employ. In this thesis, we develop methods to perform network protocol testing and verification, with the goal to make the techniques more accessible and readily adoptable. We examine how to formulate correctness requirements for ad hoc routing protocols used to set up forwarding paths in wireless networks. Model checking is a way to verify such requirements automatically. We investigate scalability of finite-state model checking, in terms of network size and topological complexity, and devise a manual abstraction technique to improve scalability. A methodology combining simulations, emulations, and real world experiments is developed for analyzing the performance of wireless protocol implementations. The technique is applied in a comparison of the ad hoc routing protocols AODV, DSR, and OLSR. Discrepancies between simulations and real world behavior are identified; these are due to absence of realistic radio propagation and mobility models in simulation. The issues are mainly related to how the protocols sense their network surroundings and we identify improvements to these capabilities. Finally, we develop a methodology and a tool for automatic verification of safety properties of infinite-state network protocols, modeled as graph transformation systems extended with negative application conditions. The verification uses symbolic backward reachability analysis. By introducing abstractions in the form of summary nodes, the method is extended to protocols with recursive data structures. Our tool automatically verifies correct routing of the DYMO ad hoc routing protocol and several nontrivial heap manipulating programs.

L'attaque de retransmission sélective est une menace sérieuse dans les réseaux de capteurs sans fil (WSN), en particulier dans les systèmes de surveillance. Les noeuds peuvent supprimer de manière malicieuse certains paquets de données sensibles, ce qui risque de détruire la valeur des données assemblées dans le réseau et de diminuer la disponibilité des services des capteurs. Nous présentons un système de sécurité léger basé sur l'envoi de faux rapports pour identifier les attaques de retransmission sélective après avoir montré les inconvénients des systèmes existants. Le grand avantage de notre approche est que la station de base attend une séquence de faux paquets à un moment précis sans avoir communiqué avec les noeuds du réseau. Par conséquent, elle sera capable de détecter une perte de paquets. L'analyse théorique montre que le système proposé peut identifier ce type d'attaque et peut alors améliorer la robustesse du réseau dans des conditions d'un bon compromis entre la fiabilité de la sécurité et le coût de transmission. Notre système peut atteindre un taux de réussite élevé d‟identification face à un grand nombre de noeuds malicieux, tandis que le coût de transmission peut être contrôlé dans des limites raisonnables. / The selective forwarding attack is a serious threat in wireless sensor networks (WSN), especially in surveillance systems. Nodes can maliciously delete some sensitive data packets, which could destroy the value of the data assembled in the network and reduce its sensors availability. After describing the drawbacks of the existing systems in this thesis, we will present a lightweight security system based on sending fake reports used to identify selective forwarding attacks. The great advantage in our approach is that the base station expects a number of packets at a specific time. Therefore, it will be able to detect missing or delayed packets. Theoretical analysis shows that the proposed system can identify this type of attack, which will improve the robustness of the network under conditions of a good tradeoff between the security, reliability and communication overhead. Our system can achieve a high ratio of identification when facing a large number of malicious nodes, while the communication overhead can be controlled within reasonable bounds.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este trabalho propõe uma nova métrica denominada AP (Alternative Path), a ser utilizada para o cálculo de rotas em protocolos de roteamento em redes em malha sem fio. Esta métrica leva em consideração a interferência causada por nós vizinhos na escolha de uma rota para um destino. O desempenho da métrica AP é avaliado e comparado com o da métrica ETX (Expected Transmission Count) e com o da métrica número de saltos (Hop Count). As simulações realizadas mostram que a métrica AP pode propiciar desempenho superior à rede quando comparada com as outras duas métricas. A métrica AP apresenta melhor desempenho em cenários com maior diversidade de caminhos alternativos. / This work proposes a new metric, AP (Alternative Path), to be used in the calculation of routes in wireless mesh network routing protocols. This new metric takes into account the interference caused by neighbor nodes when choosing a route for a destination. The performance of the AP metric is evaluated and compared to the ETX (Expected Transmission Count) and Hop count metrics. Simulations show that AP can provide superior performance to the network when compared with the other two metrics. The AP metric shows a better performance in networks with a wider variety of alternative paths.

Les Réseaux de Capteurs Sans Fil (RCSF) sont de plus en plus exploités par des applications diverses grâce à leur facilité de déploiement et d’auto-configuration. Les applications de collecte de données qui utilisent les RCSF ont souvent un profil convergecast : l’ensemble des données récoltées par tous les capteurs du réseau sont acheminées vers un puits de collecte, grâce à une communication multi-saut. Pendant l’acheminement des données des nœuds de collecte vers le puits, des goulots d’étranglement sont fréquemment observés, principalement au voisinage du puits. Cela est du à la congestion et au phénomène d’entonnoir couramment observé sur le trafic de données ayant un profile convergecast. Outre un risque accru de collision, cela entraîne le débordement des files d’attente des nœuds concernés conduisant à des pertes de données. Cette perte réduit le taux de livraison au puits entraînant une baisse du débit du réseau. Afin de réduire ces pertes et de permettre un meilleur taux de livraison au puits, le trafic doit être équitablement réparti au niveau de chaque saut pendant l’acheminement. Dans cette thèse, nous avons d’une part proposé S-CoLBA (Single channel Collaborative Load Balancing Algorithm), un protocole mono-canal de routage dynamique avec équilibrage de la charge. Sa métrique de routage est basée sur le délais moyen d’accès au medium radio par nœud. Chaque nœud choisit comme prochain saut à destination du puits, un de ses voisins ayant le délais d’accès le plus court. S-CoLBA intègre également une surveillance permanente des files d’attente des nœuds afin de prévenir la congestion et d’éviter le débordement de ces files. D’autre part, nous avons adapté S-CoLBA pour le rendre utilisable dans un réseau multicanal. Cette version du protocole s’appelle M-CoLBA (pour Mulitchannel CoLBA). M-CoLBA évite la congestion en équilibrant la charge grâce à une répartition du trafic au niveau de chaque saut du réseau. Dans un réseau multicanal, le problème de support de diffusion se pose. M-CoLBA introduit des périodes de synchronisations où tous les nœuds utilisent le même canal pour échanger les informations de routage. Ces périodes de synchronisation contribuent à allonger les délais de bout en bout des paquets. Nous avons ainsi optimisé M-CoLBA en "surchargeant" les acquittements des trames avec les informations de routage ( piggybacking) et les états des files d’attente. Cela évite de passer par des périodes de synchronisation pour diffuser ces informations. Cette version optimisée s’appelle ABORt ( Acknowledgement-Based opportunistic Routing protocol). Dans un cas de trafic de type convergecast, ABORt induit une diversité des routes prises par les données collectées, ce qui est bénéfique à la quantité de données transportées et à la robustesse de la solution. Les contributions ont été évaluées par simulation et expérimentation dans un réseau monocanal et multicanal. Les résultats montrent que nos contributions améliorent le taux de livraison des données au puits, optimisent le délais de bout en bout et réduisent la quantité de trafic de contrôle comparé à des solutions déjà existantes. / The popularity of wireless sensor networks (WSNs) is increasing due to their ease ofdeployment and auto-configuration capabilities. They are used in different applica-tion domains including data collection with convergecast scenarios. In convergecast,all data collected in the network is destined to one common node usually called thesink. In case of high carried traffic load and depending on the used routing policy,this many-to-one data collection leads to congestion and queue overflow mainly innodes located near the sink. Congestion and queue overflow reduce delivery ratiothat negatively affects the network efficiency.Wireless sensor nodes are resource constrained devices with limited buffers sizeto store and forward data to the sink. Introducing multichannel communication inWSNs helps to increase the carried traffic load thanks to allowing parallel data trans-mission and reduction of contention and interference. With high traffic load, thenumber of data packets travelling from leaf nodes towards the sink becomes higher.In case the routing scheme does not balance the traffic load, it will be unfairly dis-tributed between forwarding nodes. Thus, nodes that are in part of the routing will beoverloaded while others are less used. Overloaded nodes increase the risk of conges-tion and queue overflow leading to data loss that reduces the throughput. Therefore,we need to couple the routing protocols with traffic load balancing scheme in hightraffic load network scenarios.The goal of this thesis is to propose an efficient routing solution to prevent con-gestion and queue overflow in high data rate convergecast WSNs, in such a way, tooptimize data delivery ratio at the sink node.On the one hand, we proposed a single channel traffic load balancing routingprotocol, named S-CoLBA (Single channel Collaborative Load balancing routing).It relies on data queueing delay metric and best score (according to the value of themetric) next hop neighbors to fairly distribute traffic load in per hop basis in the net-work. Since the carried traffic load increases in multichannel communication, onthe other hand, we adapted our contribution to cope with multichannel WSNs andwe named it as Multichannel CoLBA (M-CoLBA). As broadcasting information isnot straightforward in multichannel, we optimize M-CoLBA to use piggybackingscheme for routing information sharing in the network. This enhanced version iscalled ABORt for Acknowledgement-Based opportunistic Routing protocol and re-lies on ACK frames to share routing information. Doing so helps to optimize dataframe end-to-end delay and to reduce the transmitted beacons in the network. ABORtfairly distributes traffic load in the network and avoids congestion and queue over-flow.We evaluated the performance of our contributions in both simulation using Con-tiki OS Cooja simulator and experiment (only for S-CoLBA) on TelosB motes. Ob-tained results in both simulation and experiment confirm the efficiency of our routingprotocols in term of packet delivery ratio and queue overflow compared to some ex-isting routing protocols in the literature.

Mobile Ad-hoc Network (MANET) is a group of mobile devices that can form a network, interconnect and share resources without the use of any fixed network infrastructure or centralised management. MANET is exposed to security attacks because of its fundamental characteristics such as open medium, dynamic topology and lack of central monitoring. The black hole attack is one example of the attacks MANET is exposed to. In black hole attack, a malicious node misleadingly claims to have an updated route to the destination node, absorbs and drops the packets that are supposed to be forwarded to the destination node. The common MANET reactive routing protocols are Ad-hoc on-demand Distance Vector (AODV) and Dynamic Source Routing (DSR). These protocols are easily attacked by the black hole during the route discovery process. This research therefore studies black hole attack in detail and assesses the performance of AODV and DSR under black hole attack. The work is achieved by simulating the two protocols under regular operation and under black hole attack using Network Simulator 2 (NS-2). The protocols are analysed using packet delivery ratio, throughput and end-to-end delay as performance metrics. The research further compares the black hole attack solutions that have been previously proposed and determines the solution that performs better than others. The simulation results show that MANET under normal operating environment out performs MANET attacked by black hole, and that AODV is more vulnerable to black hole attack than DSR. The comparison study of the existing black hole attack solutions show that SAODV is the best effective black hole attack removal technique. But when considering the solution that brings no negative impact to the normal operation of the network, IDSAODV is the best solution. / Computing / M. Sc. (Computer Science)

MATEUS, Bruno Góis. Análise sobre o impacto da densidade veicular, da carga da rede e da mobilidade no desempenho de protocolos de roteamento para redes veiculares. 2010. 137 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências, Departamento de Computação, Fortaleza-CE, 2010. / Submitted by guaracy araujo (guaraa3355@gmail.com) on 2016-06-06T19:00:35Z No. of bitstreams: 1 2010_dis_bgmateus.htm: 516 bytes, checksum: 4c8310e1377750fc5ac0860e74c26066 (MD5) / Approved for entry into archive by guaracy araujo (guaraa3355@gmail.com) on 2016-06-06T19:01:05Z (GMT) No. of bitstreams: 1 2010_dis_bgmateus.htm: 516 bytes, checksum: 4c8310e1377750fc5ac0860e74c26066 (MD5) / Made available in DSpace on 2016-06-06T19:01:05Z (GMT). No. of bitstreams: 1 2010_dis_bgmateus.htm: 516 bytes, checksum: 4c8310e1377750fc5ac0860e74c26066 (MD5) Previous issue date: 2010 / Advances in mobile computing and wireless communications have made possible the development of the Intelligent Transportation System, which contain the vehi- cular networks. There, routing is a challenging task due to the high node mobility, the instability of wireless links and the diversity of scenarios. For this reason, several routing protocols have been designed with the goal of solving one or more speci c problems of each scenario. However, although there are several proposed solutions to the routing problem in vehicular networks, none of them has achieved a satisfac- tory performance in more than one scenario, such as urban and highway. Thus, in this work, we rst analyze with simulations the impact of density, the network load and the mobility pattern in the performance of routing protocols for these networks. Then, we provide new directions for designing e cient vehicular network routing protocols, able to adapt to urban and highway scenarios. To achieve this goal, four existing protocols were evaluated in urban and highway scenarios. / Os avanços alcançados na computação móvel e na comunicação sem o levaram ao desenvolvimento do Sistema Inteligente de Transporte, onde se pode destacar as redes veiculares. Nelas, o roteamento é uma tarefa desa adora devido à alta mobi- lidade dos nós, à instabilidade dos enlaces sem- o e a diversidade de cenários. Por essa razão, diversos protocolos de roteamento foram projetados com o objetivo de solucionar um ou mais problemas especí cos de cada cenário. Entretanto, apesar de existirem várias soluções propostas para o problema do roteamento em redes veicu- lares, nenhuma delas alcançou um desempenho satisfatório em mais de um cenário, como urbano e rodovia. Sendo assim, nesta dissertação, analisamos através de si- mulações o impacto da densidade, da carga da rede e da mobilidade no desempenho de um protocolo de roteamento para fornecer diretrizes para os projetistas de redes veiculares desenvolverem protocolos de roteamento e cientes, capazes de se adaptar aos cenários urbano e de rodovia. Para alcançar esse objetivo, quatro protocolos existentes na literatura foram avaliados nos cenários urbano e de rodovia, dois deles voltados diretamente para redes veiculares e os outro dois tradicionais de redes —d ho™.

La tendance actuelle des réseaux de capteurs sans fil est d’avoir un seul réseau supportant plusieurs applications et fournissant plusieurs QoS. Dans cette thèse, nous étudions les techniques de cross-layering afin d’améliorer les performances et de fournir de la QoS. Tout d’abord, nous généralisons le concept de la méthode d’accès MaCARI en proposant une architecture multi-couches où plusieurs combinaisons de protocoles MAC-routage sont utilisées. Une file d’attente est associée à chaque combinaison, et chaque combinaison est activée pour une période précise. Le but est de profiter de ces combinaisons pour offrir différentes QoS. Cependant, cette architecture cause un problème de dimensionnement des périodes, ce qui a un impact sur les performances du réseau. Nous proposons, ensuite, des techniques de cross-layering en échangeant les paquets entre les différentes files d’attente afin de résoudre le problème de dimensionnement. Durant sa période, chaque combinaison traite tous les paquets de sa file d’attente ainsi que les paquets des files d’attente d’autres périodes. Nous montrons par simulation que notre approche améliore les performances du réseau. / The current trend in wireless sensor networks is to have a single network supporting serveral applications and providing several QoS. In this thesis, we study the cross-layering techniques in order to improve the network performance and provide several QoS. Fistly, we generalize the concept of the access method MaCARI by proposing a multi-stack architecture in which several MAC-routing combination protocols are used. A queue is associated to each combination, and each combination is active for a specified period. The purpose consists in using these combinations in order to provide different QoS. However, this architecture yields to a dimensioning problem for the periods reducing the network performance. Secondly, we propose cross-layering techniques by exchanging packets between different queues to solve the dimensioning problem. During its period, each combination treats all the packets of its queue and the packets related to queues associated to other periods. We show by simulations that our approach improves the network performance.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este trabalho propõe uma nova métrica denominada AP (Alternative Path), a ser utilizada para o cálculo de rotas em protocolos de roteamento em redes em malha sem fio. Esta métrica leva em consideração a interferência causada por nós vizinhos na escolha de uma rota para um destino. O desempenho da métrica AP é avaliado e comparado com o da métrica ETX (Expected Transmission Count) e com o da métrica número de saltos (Hop Count). As simulações realizadas mostram que a métrica AP pode propiciar desempenho superior à rede quando comparada com as outras duas métricas. A métrica AP apresenta melhor desempenho em cenários com maior diversidade de caminhos alternativos. / This work proposes a new metric, AP (Alternative Path), to be used in the calculation of routes in wireless mesh network routing protocols. This new metric takes into account the interference caused by neighbor nodes when choosing a route for a destination. The performance of the AP metric is evaluated and compared to the ETX (Expected Transmission Count) and Hop count metrics. Simulations show that AP can provide superior performance to the network when compared with the other two metrics. The AP metric shows a better performance in networks with a wider variety of alternative paths.

Saving energy and increasing network lifetime are significant challenges in the field of Wireless Sensor Networks (WSNs). Energy-aware routing protocols have been introduced for WSNs to overcome limitations of WSN including limited power resources and difficulties renewing or recharging sensor nodes batteries. Furthermore, the potentially inhospitable environments of sensor locations, in some applications, such as the bottom of the ocean, or inside tornados also have to be considered. ZigBee is one of the latest communication standards designed for WSNs based on the IEEE 802.15.4 standard. The ZigBee standard supports two routing protocols, the Ad hoc On-demand Distance Vector (AODV), and the cluster-tree routing protocols. These protocols are implemented to establish the network, form clusters, and transfer data between the nodes. The AODV and the cluster-tree routing protocols are two of the most efficient routing protocols in terms of reducing the control message overhead, reducing the bandwidth usage in the network, and reducing the power consumption of wireless sensor nodes compared to other routing protocols. However, neither of these protocols considers the energy level or the energy consumption rate of the wireless sensor nodes during the establishment or routing processes.