Recent technique advances have made sensor nodes to be smaller, cheaper and more powerful. Compared with traditional centralized sensing systems, wireless sensor networks are very easy to deploy and can be deployed densely. They have a better sensing coverage and provide more reliable information delivery. Those advantages make wireless sensor networks very useful in a wide variety of applications. As one of active research areas, acoustic monitoring with wireless sensor networks is still new, and very few applications can recognize human voice, discriminate human speech and music, or identify individual speakers. In this thesis work, we designed and implemented an acoustic monitoring system with a wireless sensor network to classify human voice versus music. We also introduce a new, effective sound source localization method, using Root Mean Square (RMS) detected by different nodes of a wireless sensor network to estimate the speaker's location. The experimental results show that our approaches are effective. This research could form a basis for further developing speech recognition, speaker identification, even emotion detection with wireless sensor networks.

Wireless sensor network plays a significant role in the design of future Smart Grid, mainly for the purpose of environment monitoring, data acquisition and remote control. Sensors deployed on the utility poles on the power transmission line are used to collect environment information and send them to the substations for analysis and management. However, the transmission is suffered from erasures and errors along the transmission channels. In this thesis, we consider a line network model proposed in [1] and [2]. We first analyze several different erasure codes in terms of overhead and encoding/decoding costs, followed by proposing two different coding schemes for our line network. To deal with both erasures and errors, we combine the erasure codes and the traditional error control codes, where an RS code is used as an outer codes in addition to the erasure codes. Furthermore, an adaptive RS coding scheme is proposed to improve the overall coding efficiency over all SNR regions. In the end, we apply network coding with error correction of network errors and erasures and examine our model from the mathematical perspective. / Graduate

Secure wireless communications among sensor nodes is critical to the deployment of wireless sensor networks. However, resource limited sensor nodes cannot afford complex cryptographic algorithms. In this thesis, we propose a low complexity and energy efficient reconfigurable feedback shift register (RFSR) stream cipher, link layer encryption framework RSec and authentication protocol RAuth. RFSR adds one new dimension, reconfigurable cipher structure, to the existing stream ciphers. The proposed RFSR is implemented on a field programmable gate array platform. Simulation results show that much lower power consumption, delay and transmission overhead are achieved compared to the existing microprocessor based cipher implementations. The RSec framework utilizes RFSR ciphers to guarantee message confidentiality. By comparing with other encryption frameworks in terms of energy efficiency, RSec achieves the best benchmark. The RAuth protocol is designed on top of RFSR and RSec. It provides excellent authentication speed and security level by comparing with other authentication protocols. / Graduate / 0544 / 0984 / zggyzz@gmail.com

The nature and complexity of the security threats faced by our society in recent years have made it clear that a smart pervasive surveillance system constitutes the most effective cure, as it presents a conducive framework for seamless interaction between preventative capabilities and investigative protocols. Applications such as wild-life preserve monitoring, natural disaster warnings, and facility surveillance tend to be characterized by large and remote geographic areas, requiring large numbers of unattended sensor nodes to cover the volume-of-interest. Such large unattended sensor networks add new challenges as well as complicate the system management problem. Such challenges can be in the form of distributed operation with collaborative decision making, adaptive performance, and energy-aware strategies, to name a few. To meet the challenges of these mission-critical applications, the sensor system must exhibit capabilities such as heterogeneous and self-organized behaviour, data and information fusion, and collaborative resources control and management. Sensor Management (SM) refers to the process that plans and controls the use of the sensor nodes in a manner that synergistically maximizes the success rate of the whole system in achieving the goals of its mission in assessing the situation in a timely, reliable, and accurate fashion. Managing heterogeneous sensors involves making decisions and compromises regarding alternate sensing strategies under time and resource availability constraints. As a result, the performance of the collective sensors dictates the performance of the entire system. Consequently, there is a need for an intelligent Sensor Management Framework (SMF) to drive the system performance. SMF provides a control system to manage and coordinate the use of sensing resources in a manner that maximizes the system success rate in achieving its goals. An SMF must handle an overwhelming amount of information collected, and adapt to the highly dynamic environments, in addition to network and system limitations. This thesis proposes a resource-aware and intelligent SMF for managing pervasive sensor systems in surveillance context. The proposed SMF considerably improves the process of information acquisition by coordinating the sensing resources in order to gather the most reliable data from a dynamic scene while operating under energy constraints. The proposed SMF addresses both the operation of the coordination paradigm, as well as, the local and collaborative decision making strategies. A conceptual analysis of the SM problem in a layered structure is discussed to introduce an open and flexible design framework based on the service-oriented architecture to provide a modular, reusable, and extendable framework for the proposed SMF solution. A novel sensor management architecture, called Extended Hybrid Architecture for Sensor Management (E-HASM), is proposed. E-HASM combines the operation of the holonic, federated, and market-based architectures in a complementary manner. Moreover, a team-theoretic formulation of Belief-Desire-Intention (BDI), that represent the E-HASM components, is proposed as a mechanism for effective energy-aware decision making to address the local sensor utility. Also, intelligent schemes that provide adaptive sensor operation to the changes in environment dynamics and sensor energy levels are designed to include adaptive sleep, active sensing, dynamic sensing range, adaptive multimodality, and constrained communication. Furthermore, surveillance systems usually operate under uncertainty in stochastic environment. Therefore, this research formulates the collaborative decision-making entities as Partially Observable Markov Decision Processes (POMDP). To increase the tracking quality and the level of the information reliability, cooperation between the sensors is adopted, which adds an extra dimension in the design of the proposed SMFs. The propose SMF is implemented using the Jadex platform and is compared to the popular centralized architecture. The results illustrate the operation of the proposed SMF outperforms in terms of tracking quality, detection rate, energy consumption, network lifetime, and scalability.

Τα κυψελικά αυτόματα (ΚΑ) αποτελούν την εξιδανίκευση ενός φυσικού συστήματος όπου ο χώρος και ο χρόνος είναι διακριτοί και οι φυσικές ποσότητες λαμβάνουν μόνο ένα πεπερασμένο σύνολο τιμών. Τα κυψελικά αυτόματα αποτελούνται από ένα πλέγμα με διακριτούς πανομοιότυπους κόμβους. Κάθε σημείο-κόμβος του πλέγματος χαρακτηρίζεται από μία τιμή η οποία δεν είναι αυθαίρετη, αλλά λαμβάνεται από ένα συγκεκριμένο σύνολο ‘επιτρεπτών’ ακέραιων τιμών. Οι τιμές αυτών των κόμβων του πλέγματος εξελίσσονται από τη μία χρονική στιγμή στην άλλη σύμφωνα με προκαθορισμένους τοπικούς κανόνες. Η συνολική δομή αποτελεί ένα μοντέλο παράλληλου υπολογισμού. ΄Οταν η απλή δομή του μοντέλου επαναλαμβάνεται, προκύπτουν πολύπλοκα πρότυπα που μπορούν να προσομοιώσουν ποικίλα πολύπλοκα φυσικά φαινόμενα και συστήματα. Χρησιμοποιούμε τα κυψελικά αυτόματα για να προσομοιώσουμε έναν αλγόριθμο ελέγχου τοπολογίας για ασύρματα δίκτυα αισθητήρων. Τα ασύρματα δίκτυα αισθητήρων αποτελούνται από ένα μεγάλο αριθμό διασκορπισμένων αισθητήρων-κόμβων που λειτουργούν με μπαταρίες. Σκοπός του προβλήματος ελέγχου τοπολογίας σε ασύρματα δίκτυα αισθητήρων είναι η επιλογή κατάλληλου υποσυνόλου κόμβων ικανών να παρακολουθούν μια περιοχή με στόχο τη μικρότερη δυνατή κατανάλωση ενέργειας και ως εκ τούτου την επέκταση της διάρκειας ζωής του δικτύου. / Cellular automata (CA) are an idealization of a physical system where space and time are discrete and the physical quantities take only a finite set of values. Cellular automata consist of a regular grid of identical cells-nodes. Each node is characterized by a non arbitrary value selected by a specific set of appropriate integers. The values of the nodes change over time according to predefined localized rules. The overall structure can be viewed as a parallel processing device. This simple structure when iterated several times produces complex patterns displaying the potential to simulate different sophisticated natural phenomena. We use cellular automata for simulating a topology control algorithm in Wireless Sensor Networks (WSNs). WSNs are composed of a large number of distributed sensor nodes operating on batteries; the objective of the topology control problem in WSNs is to select an appropriate subset of nodes able to monitor a region at a minimum energy consumption cost thus extending the network lifetime.

Este trabalho avalia o desempenho de um controlador fuzzy (tipo Takagi-Sugeno-Kang) quando, utilizando tecnologia sem fio para conectar as entradas e a saída do controlador aos sensores/atuadores, sofre perda das informações destes canais, resultado de perdas de pacotes. Tipicamente são utilizados controladores PID nas malhas de controle. Assim, o estudo realizado compara os resultados obtidos com os controladores fuzzy com os resultados dos controladores PID. Além disso, o trabalho visa estudar o comportamento deste controlador implementado em uma arquitetura microprocessada utilizando números inteiros nos cálculos, interpolação com segmentos de reta para as funções de pertinência da entrada e singletons nas funções de pertinência da saída. Para esse estudo foi utilizado, num ambiente Matlab/Simulink, um controlador fuzzy e o aplicativo True Time para simular o ambiente sem fio. Desenvolvido pelo Departamento de Controle Automático da Universidade de Lund, o True Time é baseado no Matlab/Simulink e fornece todas as ferramentas necessárias para a criação de um ambiente de rede (com e sem fio) virtual. Dado o paradigma de que quanto maior for a utilização do canal, maior a degradação do mesmo, é avaliado o comportamento do sistema de controle e uma proposta para diminuir o impacto da perda de pacotes no controle do sistema, bem como o impacto da variação das características internas da planta e da arquitetura utilizada na rede. Inicialmente são realizados ensaios utilizando-se o controlador fuzzy virtual (Simulink) e, posteriormente, o controlador implementado com dsPIC. Ao final, é apresentado um resumo desses ensaios e a comprovação dos bons resultados obtidos com um controlador fuzzy numa malha de controle utilizando uma rede na entrada e na saída do controlador. / This work evaluates the performance of a fuzzy controller (Takagi-Sugeno-Kang) that uses wireless technology to connect the inputs and the output of the controller to sensors / actuators, and with the loss of information from these channels, the result of packet loss. PID controllers are typically used in control loops. Thus, the study compares the results obtained with the fuzzy controllers with the results of PID controllers. Moreover, the work aims to study the behavior of this controller implemented in a microprocessor architecture using integer calculations, interpolation with straight line segments for the membership functions of input and singletons in the output membership functions. For this study it was used in a Matlab/Simulink, a fuzzy controller and the application True Time to simulate wireless environment (Developed by the Department of Automatic Control at Lund University). It is based on MATLAB/Simulink and provides all the tools necessary to create a virtual network environment (wired and wireless). When we increase the occupation of the channel we increase the degradation of it. Under this conditions, is rated the behavior of the control system and is evaluated, and actions were proposal to reduce the impact of packet loss in the control system, as well as the impact of variations in the internal characteristics of plant and architecture used in the network. Initially, tests are conducted using the virtual fuzzy controller (Simulink ) and thereafter, the controller implemented with dsPIC. Finally, a summary of testing and verification of results are presented.

As cidades estão a seu tempo e a seu modo, modernizando os serviços prestados à população. Entre os diversos fatores que estão contribuindo para esta evolução estão a diversificação e proliferação de sensores, nos diversos domínios de serviços das cidades, e os novos canais de comunicação com os munícipes, entre eles, as redes sociais e mais recentemente os sistemas crowdsensing, motivados pelos anseios sociais, por melhores serviços públicos e pela popularização dos dispositivos móveis. Nesta direção, a eficiência administrativa é um fator essencial, uma vez que as cidades estão se mostrando mais complexas na medida em que cresce a população nas áreas urbanas. A utilização de técnicas de sistemas distribuídos para que múltiplos domínios de serviços usufruam da mesma infraestrutura computacional, pode auxiliar na eficiência das cidades, evitando gastos administrativos duplicados e até mesmo, possibilitando a correlação de eventos entre os serviços, favorecendo a identificação de fatores de causalidades e assim, a tomada de decisões administrativas mais objetivas e precisas. Neste contexto, este trabalho concentra-se na análise de um middleware direcionado à gestão de cidades para coleta, integração e interpretação dos dados de sensores, pertencentes aos serviços disponíveis da própria cidade, junto com os dados do sensoriamento colaborado pelos cidadãos. Para avaliação do conceito foi investigado o cenário de monitoração da conservação de vias públicas. Após 3 meses de coletas de dados por um sistema de sensoriamento automático, totalizando mais de 360 mil pontos e também mais de 90 relatórios pelo sensoriamento participativo, verificou-se que um sistema distribuído pode realizar a interpretação de séries históricas, engajar os munícipes apoiar a manutenção dos serviços da cidade e também indicar objetivamente aos gestores públicos os pontos que devem ser prioritariamente atendidos. Aliar ferramentas pelas quais o cidadão pode, de acordo com sua necessidade, convicção e altruísmo, exercer influência nos gestores públicos com o suporte de informação contínua e critérios objetivos das redes de sensores, pode estimular a continua excelência dos serviços públicos. / The cities in their own way and time are improving their services provided to the population. Among several factors that are contributing to this trend are the diversification and proliferation of sensors in various services domains of cities and new communication ways with citizens, for instance, social networks and more recently, crowdsensing systems, motivated by social expectations for better public services and the popularity of mobile devices. In this direction, administrative efficiency is a key factor, since the cities are proving more complex with increasing the population in urban areas. Techniques of distributed systems to share the same computing infrastructure to multiple service domains, can assist in the efficiency of cities, avoiding duplicate administrative costs and even allowing event correlation between services, providing the identification of causality factors, thus making management decisions more objective and accurate. In this context, this research focuses on analysis of a middleware directed to city management for collection, integration and interpretation of sensors data, present in city services, along with the sensing data contributed by citizens. For concept evaluation, was investigated the scenario of conservation of public streets. After 3 months of data collection by an automatic sensing system comprising more than 360 thousand points and also 94 reports of collaborative sensing, it was found that a distributed system can perform the interpretation of historical series; engage the citizens to support maintenance of city services and indicate objectively the points that should primarily be fix by public managers. Combining tools, which citizens can, according to their need, conviction, altruism, exert their own influence in public management and the continuous information support to objective criteria of sensor networks, can stimulate the continued excellence of public services.

Nos recherches se situent à l'intersection des sphères académiques et industrielles et des organismes de standardisation pour permettre la mise en place d'un Internet des objets (IoT) sécurisé et efficace.Nous étudions des solutions de sécurisation en parcourant les standards de manière ascendante.En premier lieu, nous constatons que l'accélération matérielle des algorithmes de cryptographie est nécessaire pour les équipements formant l'IoT car il permet une reduction de deux ordres de grandeur des durées de calcul.Le surcoût des opérations cryptographiques n'est cependant qu'un des facteurs qui gouverne la performance globale dans le contexte des systèmes en réseau.Nous montrons à travers l'implementation d'applications pratiques que les dispositifs de sécurité de la couche 2 n'augmentent que de quelques pourcents la dépense énergétique totale.Ceci est acceptable, même pour les systèmes les plus contraints, comme ceux utilisant la recuperation d'énergie ambiante.La sécurité de la couche 2 contraint de faire confiance à chacun des noeuds du chemin de communication comprenant potentiellement des éléments malveillants, nous devons donc protéger le flux de données par un mécanisme de bout en bout.Nous étudions le protocole DTLS, standard de l'IETF pour la sécurité de l'IoT.Nous contribuons aux discussions sur l'intérêt de DTLS dans les environnements contraints, à la fois dans les organismes de standardisation et de recherche.Nous évaluons DTLS de manière étendue avec différents réseaux à cycle d'activité ou duty cycle au travers d'expérimentations, d'émulations et d'analyses.De manière surprenante, nos résultats démontrent la très faible performance de DTLS dans ces réseaux où l'efficacité énergétique est primordiale.Comme un client et un serveur DTLS échangent beaucoup de paquets de signalisation, la connection DTLS prends entre quelques secondes et quelques dizaines de secondes, ceci pour plusieurs des protocoles étudiés.DTLS a été conçu pour les communications de bout en bout dans l'Internet classique, contrairement au nouveau protocol CoAP qui lui est destiné à des machines contraintes en facilitant le traffic asynchrone, les communications de groupe et le besoin de stockage intermédiaire.Donc, en plus du problème de performance, l'architecture de sécurité basée sur DTLS n'est pas capable de répondre aux contraintes de ces dispositifs et CoAP devient inutilisable.Nous proposons une architecture qui s'appuie à la fois sur une approche centrée sur le contenu et sur la notion classique de connection.L'échange des clefs est fait à travers des canaux sécurisés établis par DTLS, mais la notion d'états entre les entités de communication est supprimée grâce au concept d'objets sécurisés.Le mécanisme proposé resiste aux attaques par rejeu en regroupant les capacités de controle d'accès avec les en-tetes de communication CoAP.OSCAR, notre architecture à objets sécurisés, supporte intrinsèquement les communications de groupe et le stockage intermédiaire, sans perturber le fonctionnement à cycle d'activité de la radio des équipements contraintes.Les idées d'OSCAR sont discutés par les groupes de standardisation de l'Internet en vue d'être intégrées dans les standards à venir. / Our research explores the intersection of academic, industrial and standardization spheres to enable secure and energy-efficient Internet of Things. We study standards-based security solutions bottom-up and first observe that hardware accelerated cryptography is a necessity for Internet of Things devices, as it leads to reductions in computational time, as much as two orders of magnitude. Overhead of the cryptographic primitives is, however, only one of the factors that influences the overall performance in the networking context. To understand the energy - security tradeoffs, we evaluate the effect of link-layer security features on the performance of Wireless Sensors Networks. We show that for practical applications and implementations, link-layer security features introduce a negligible degradation on the order of a couple of percent, that is often acceptable even for the most energy-constrained systems, such as those based on harvesting.Because link-layer security puts trust on each node on the communication path consisted of multiple, potentially compromised devices, we protect the information flows by end-to-end security mechanisms. We therefore consider Datagram Transport Layer Security (DTLS) protocol, the IETF standard for end-to-end security in the Internet of Things and contribute to the debate in both the standardization and research communities on the applicability of DTLS to constrained environments. We provide a thorough performance evaluation of DTLS in different duty-cycled networks through real-world experimentation, emulation and analysis. Our results demonstrate surprisingly poor performance of DTLS in networks where energy efficiency is paramount. Because a DTLS client and a server exchange many signaling packets, the DTLS handshake takes between a handful of seconds and several tens of seconds, with similar results for different duty cycling protocols.But apart from its performance issues, DTLS was designed for point-to-point communication dominant in the traditional Internet. The novel Constrained Ap- plication Protocol (CoAP) was tailored for constrained devices by facilitating asynchronous application traffic, group communication and absolute need for caching. The security architecture based on DTLS is, however, not able to keep up and advanced features of CoAP simply become futile when used in conjunction with DTLS. We propose an architecture that leverages the security concepts both from content-centric and traditional connection-oriented approaches. We rely on secure channels established by means of DTLS for key exchange, but we get rid of the notion of “state” among communicating entities by leveraging the concept of object security. We provide a mechanism to protect from replay attacks by coupling the capability-based access control with network communication and CoAP header. OSCAR, our object-based security architecture, intrinsically supports caching and multicast, and does not affect the radio duty-cycling operation of constrained devices. Ideas from OSCAR have already found their way towards the Internet standards and are heavily discussed as potential solutions for standardization.

This thesis documents a sensor networking project with an interest in internal environment monitoring in relation to thermal comfort. As part of this project sensor nodes were designed, built and deployed. Data was collected from the nodes via a wired Ethernet network and was stored in a database. The network remains operational several years after its initial deployment. The collected data was analyzed in conjunction with data from a local meteorological station and the building's smart fiscal energy meters. The analysis suggests the possibility of automated thermal comfort classification using data from a sensor network.

This research concerns the in-use performance of light-gauge steel modular construction used for residential purposes. The aim was to investigate ways to reduce the in-use energy consumption of new buildings, while ensuring thermal comfort. Data were collected from two case study buildings in the UK, one in Loughborough and the other in London, using a variety of methods including building measurement, building monitoring, inspections, and a detailed review of the construction documentation. The case study buildings were monitored using EnOcean enabled wireless sensor networks and standalone temperature sensors. Monitoring data included electricity consumption in individual rooms, often by end use, space heating use, internal temperature and relative humidity, and external temperature. Building measurements included blower door tests to measure fabric air leakage rates, infrared thermal imaging to identify fabric defects and weaknesses, and ventilation system flowrate measurements. Inspections and the review of documentation allowed problems with design, manufacture and construction to be identified. A particular concern for thermally lightweight construction is the risk of overheating, therefore overheating analyses were undertaken. The research identified weaknesses in the design, construction and operation of the case study buildings resulting in increased energy use and poor thermal comfort, particularly overheating. The modular construction studied requires specific design changes to improve the fabric and building services, in order to reduce energy use. There are also specific recommendations for quality control on site to ensure critical stages are correctly completed, such as installing rigid insulation. There are also more general recommendations for how a company operates because this can influence performance; there ought to be greater attention to holistic design and greater collaboration with suppliers and contractors to determine robust solutions. Overheating was a problem in the London case study, and more research is required to understand the scale of the problem. Avoidance of overheating must be a focus in the design of new buildings. The findings suggest that once the problems with the design and quality control on site are rectified, offsite modular construction can be used to consistently and reliably provide low energy homes.