A Real-Time Communication Framework for Wireless Sensor Networks

Recent advances in miniaturization and low power design have led to a flurry of activity in wireless sensor networks. Sensor networks have different constraints than traditional wired networks. A wireless sensor network is a special network with large numbers of nodes equipped with embedded processors, sensors, and radios. These nodes collaborate to accomplish a common task such as environment monitoring or asset tracking. In many applications, sensor nodes will be deployed in an ad-hoc fashion without careful planning. They must organize themselves to form a multihop, wireless communication network. In sensor network environments, much research has been conducted in areas such as power consumption, self-organisation techniques, routing between the sensors, and the communication between the sensor and the sink. On the other hand, real-time communication with the Quality of Service (QoS) concept in wireless sensor networks is still an open research field. Most protocols either ignore real time or simply attempt to process as fast as possible and hope that this speed is sufficient to meet the deadline. However, the introduction of real-time communication has created additional challenges in this area. The sensor node spends most of its life routing packets from one node to another until the packet reaches the sink; therefore, the node functions as a small router most of the time. Since sensor networks deal with time-critical applications, it is often necessary for communication to meet real time constraints. However, research that deals with providing QoS guarantees for real-time traffic in sensor networks is still in its infancy.This thesis presents a real-time communication framework to provide quality of service in sensor networks environments. The proposed framework consists of four components: First, present an analytical model for implementing Priority Queuing (PQ) in a sensor node to calculate the queuing delay. The exact packet delay for corresponding classes is calculated. Further, the analytical results are validated through an extensive simulation study. Second, report on a novel analytical model based on a limited service polling discipline. The model is based on an M/D/1 queuing system (a special class of M/G/1 queuing systems), which takes into account two different classes of traffic in a sensor node. The proposed model implements two queues in a sensor node that are served in a round robin fashion. The exact queuing delay in a sensor node for corresponding classes is calculated. Then, the analytical results are validated through an extensive simulation study. Third, exhibit a novel packet delivery mechanism, namely the Multiple Level Stateless Protocol (MLSP), as a real-time protocol for sensor networks to guarantee the traffic in wireless sensor networks. MLSP improves the packet loss rate and the handling of holes in sensor network much better than its counterpart, MMSPEED. It also introduces the k-limited polling model for the first time. In addition, the whole sending packets dropped significantly compared to MMSPEED, which it leads to decrease the consumption power. Fourth, explain a new framework for moving data from the sink to the user, at a low cost and low power, using the Universal Mobile Telecommunication System (UMTS), which is standard for the Third Generation Mobile System (3G). The integration of sensor networks with the 3G mobile network infrastructure will reduce the cost of building new infrastructures and enable the large-scale deployment of sensor network

Multipath Routing in Wireless Sensor Networks: Survey and Research Challenges

A wireless sensor network is a large collection of sensor nodes with limited power supply and constrained computational capability. Due to the restricted communication range and high density of sensor nodes, packet forwarding in sensor networks is usually performed through multi-hop data transmission. Therefore, routing in wireless sensor networks has been considered an important field of research over the past decade. Nowadays, multipath routing approach is widely used in wireless sensor networks to improve network performance through efficient utilization of available network resources. Accordingly, the main aim of this survey is to present the concept of the multipath routing approach and its fundamental challenges, as well as the basic motivations for utilizing this technique in wireless sensor networks. In addition, we present a comprehensive taxonomy on the existing multipath routing protocols, which are especially designed for wireless sensor networks. We highlight the primary motivation behind the development of each protocol category and explain the operation of different protocols in detail, with emphasis on their advantages and disadvantages. Furthermore, this paper compares and summarizes the state-of-the-art multipath routing techniques from the network application point of view. Finally, we identify open issues for further research in the development of multipath routing protocols for wireless sensor networks

A Survey of multimedia streaming in wireless sensor networks: progress, issues and design challenges

Advancements in Complementary Metal Oxide Semiconductor (CMOS) technology have enabled Wireless Sensor Networks (WSN) to gather, process and transport multimedia (MM) data as well and not just limited to handling ordinary scalar data anymore. This new generation of WSN type is called Wireless Multimedia Sensor Networks (WMSNs). Better and yet relatively cheaper sensors that are able to sense both scalar data and multimedia data with more advanced functionalities such as being able to handle rather intense computations easily have sprung up. In this paper, the applications, architectures, challenges and issues faced in the design of WMSNs are explored. Security and privacy issues, over all requirements, proposed and implemented solutions so far, some of the successful achievements and other related works in the field are also highlighted. Open research areas are pointed out and a few solution suggestions to the still persistent problems are made, which, to the best of my knowledge, so far have not been explored yet

Reliable data delivery in wireless sensor networks

Wireless sensor networks (WSN) have generated tremendous interest among researchers these years because of their potential usage in a wide variety of applications. Sensor nodes are inexpensive portable devices with limited processing power and energy resources. Sensor nodes can be used to collect information from the environment, locally process this data and transmit the sensed data back to the user. This thesis proposes a new reliable data delivery protocol for general point-to-point data delivery (unicasting) in wireless sensor networks. The new protocol is designed that aims at providing 100% reliability when possible as well as minimizing overhead and network delay. The design of the new protocol includes three components. The new protocol adopts a NACK-based hop-by-hop loss detection and recovery scheme using end-to-end sequence numbers. In order to solve the single/last packet problem in the NACK-based approach, a hybrid ACK/NACK scheme is proposed where an ACK-based approach is used as a supplement to the NACK-based approach to solve the single/last packet problem. The proposed protocol also has a new queue management scheme that gives priority to new data. By introducing the idea of a Ready_Bit and newer packet first rule in the transmission queue, nodes can detect and recover lost packets in parallel with the normal data transmission process. The performance of the new protocol is tested in a Crossbow MicaZ testbed. Experimental results show that the new protocol performs well under various system and protocol parameter settings

A study of the applicability of software-defined networking in industrial networks

173 p.Las redes industriales interconectan sensores y actuadores para llevar a cabo funciones de monitorización, control y protección en diferentes entornos, tales como sistemas de transporte o sistemas de automatización industrial. Estos sistemas ciberfísicos generalmente están soportados por múltiples redes de datos, ya sean cableadas o inalámbricas, a las cuales demandan nuevas prestaciones, de forma que el control y gestión de tales redes deben estar acoplados a las condiciones del propio sistema industrial. De este modo, aparecen requisitos relacionados con la flexibilidad, mantenibilidad y adaptabilidad, al mismo tiempo que las restricciones de calidad de servicio no se vean afectadas. Sin embargo, las estrategias de control de red tradicionales generalmente no se adaptan eficientemente a entornos cada vez más dinámicos y heterogéneos.Tras definir un conjunto de requerimientos de red y analizar las limitaciones de las soluciones actuales, se deduce que un control provisto independientemente de los propios dispositivos de red añadiría flexibilidad a dichas redes. Por consiguiente, la presente tesis explora la aplicabilidad de las redes definidas por software (Software-Defined Networking, SDN) en sistemas de automatización industrial. Para llevar a cabo este enfoque, se ha tomado como caso de estudio las redes de automatización basadas en el estándar IEC 61850, el cual es ampliamente usado en el diseño de las redes de comunicaciones en sistemas de distribución de energía, tales como las subestaciones eléctricas. El estándar IEC 61850 define diferentes servicios y protocolos con altos requisitos en terminos de latencia y disponibilidad de la red, los cuales han de ser satisfechos mediante técnicas de ingeniería de tráfico. Como resultado, aprovechando la flexibilidad y programabilidad ofrecidas por las redes definidas por software, en esta tesis se propone una arquitectura de control basada en el protocolo OpenFlow que, incluyendo tecnologías de gestión y monitorización de red, permite establecer políticas de tráfico acorde a su prioridad y al estado de la red.Además, las subestaciones eléctricas son un ejemplo representativo de infraestructura crítica, que son aquellas en las que un fallo puede resultar en graves pérdidas económicas, daños físicos y materiales. De esta forma, tales sistemas deben ser extremadamente seguros y robustos, por lo que es conveniente la implementación de topologías redundantes que ofrezcan un tiempo de reacción ante fallos mínimo. Con tal objetivo, el estándar IEC 62439-3 define los protocolos Parallel Redundancy Protocol (PRP) y High-availability Seamless Redundancy (HSR), los cuales garantizan un tiempo de recuperación nulo en caso de fallo mediante la redundancia activa de datos en redes Ethernet. Sin embargo, la gestión de redes basadas en PRP y HSR es estática e inflexible, lo que, añadido a la reducción de ancho de banda debida la duplicación de datos, hace difícil un control eficiente de los recursos disponibles. En dicho sentido, esta tesis propone control de la redundancia basado en el paradigma SDN para un aprovechamiento eficiente de topologías malladas, al mismo tiempo que se garantiza la disponibilidad de las aplicaciones de control y monitorización. En particular, se discute cómo el protocolo OpenFlow permite a un controlador externo configurar múltiples caminos redundantes entre dispositivos con varias interfaces de red, así como en entornos inalámbricos. De esta forma, los servicios críticos pueden protegerse en situaciones de interferencia y movilidad.La evaluación de la idoneidad de las soluciones propuestas ha sido llevada a cabo, principalmente, mediante la emulación de diferentes topologías y tipos de tráfico. Igualmente, se ha estudiado analítica y experimentalmente cómo afecta a la latencia el poder reducir el número de saltos en las comunicaciones con respecto al uso de un árbol de expansión, así como balancear la carga en una red de nivel 2. Además, se ha realizado un análisis de la mejora de la eficiencia en el uso de los recursos de red y la robustez alcanzada con la combinación de los protocolos PRP y HSR con un control llevado a cabo mediante OpenFlow. Estos resultados muestran que el modelo SDN podría mejorar significativamente las prestaciones de una red industrial de misión crítica

Gestion de la qualité de service et planification optimale de réseaux de capteurs multimédia sans fil

RÉSUMÉ Un RCSF est constitué d'un certain nombre d'entités (capteurs) géographiquement dispersées, de taille réduite, avec une autonomie et une puissance de traitement réduites. Ces dispositifs sont utilisés pour réaliser, de manière indépendante, des tâches comme la surveillance, le contrôle de processus industriel, etc. Les avancées en microélectronique ont conduit à l'émergence des petites caméras (type CMOS) et microphones accessibles. Ces capteurs audio-visuels peuvent être intégrés dans un RCSF pour former des RCMSF. Dans certains types d'applications, comme la surveillance des frontières, un grand nombre de ce type de capteurs est susceptible d'être déployés, sur de vastes terrains. Un volume considérable de flux audio-visuel (en plus des données) doit être transmis au centre de contrôle (le collecteur, ou SINK) pour analyse et prise de décision. Il y a donc un besoin important en termes de bande passante, avec surtout une forte contrainte en termes de délai de transmission et d'autres paramètres de RCSF. Des solutions pour le routage d'information ont été développées pour des RCSF, mais ces protocoles n'ont pas pris en compte la génération à grande échelle des données multimédia, elles sont par conséquent inadaptées aux RCMSF. Les capteurs typiquement sont omnidirectionnels, c'est-à-dire qu'ils sont capables de capter des signaux qui proviennent de toutes les directions autour d'eux. Les capteurs multimédia, en particulier les capteurs de vidéo, sont de type directionnel. Pour ce type de capteurs, l'aire de captage est limitée à un secteur donné d'un plan tridimensionnel. Malheureusement, les modèles mathématiques développés pour le placement des RCMSF conventionnels ne peuvent pas être appliqués dans le cadre de la configuration et de la planification des réseaux de capteurs directionnels. De nouveaux modèles d'optimisation sont donc nécessaires pour la capture des principaux paramètres caractérisant les capteurs directionnels. Dans cette thèse, nous abordons donc les problèmes clés suivants: le routage des données hétérogènes (scalaires et multimédia) pour les nœuds d'un RCMSF afin d'assurer une meilleure QdS aux usagers; et le déploiement optimisé de capteurs directionnels d'un RCMSF dans un espace tridimensionnel dont le but est couvrir un ensemble de points d'intérêts définis dans tel espace. Notre thèse se compose de trois articles scientifiques, chacun traitant d'une problématique bien spécifique. Le premier article traite du problème du routage d'information pour les RCMSF basé sur la QdS. Nous proposons un nouveau protocole, AntSensNet, basé sur l'heuristique de la colonie de fourmis, qui utilise plusieurs métriques de QdS pour trouver de bonnes routes pour les données multimédia et l'information scalaire. Dans la pratique, le protocole établit d'abord une structure hiérarchique sur le réseau avant de choisir les chemins appropriés pour répondre aux diverses exigences de QdS des différents types de trafic qui circulent dans le réseau. Ceci permet de maximiser l'utilisation des ressources du réseau, tout en améliorant la performance de la transmission de l'information. En outre, AntSensNet est capable d'utiliser un mécanisme efficace d'ordonnancement de paquets et de multiples chemins afin d'obtenir la distorsion minimale au moment où une application fait la transmission de la vidéo dans le réseau. Dans le deuxième article nous continuons avec le sujet de la QdS dans le RCMSFs et, plus spécifiquement, nous abordons la problématique du contrôle d'admission pour ce type de réseau. Grâce au contrôle d'admission, il est possible de déterminer si un réseau est capable de supporter un nouveau flot de données. S'il n'y a pas de contrôle d'admission dans un RCMSF, le performance du réseau sera compromis car les ressources existantes dans le réseau ne seront pas assez pour tous les flots acceptés et cela entraînera beaucoup de problèmes comme la perte de paquets des flots. Nous proposons un nouveau schéma de contrôle d'admission de nouveaux flots multimédia pour un RCMSF. Le système proposé est en mesure de déterminer si un flot de données puisse être admis dans le réseau, compte tenu de l'état actuel des liaisons de communications et l'énergie des nœuds. La décision sur l'acceptation est prise de manière distribuée, sans utiliser une entité centrale. De plus, notre schéma se présente comme un plug-in, et est adaptable à d'éventuels protocoles de routage et MAC utilisés pour la transmission de données dans les RCMSF. Nos résultats de simulation montrent l'efficacité de notre approche pour répondre aux exigences de QdS des nouveaux flots de données. Finalement, notre troisième article traite du problème du déploiement optimal des capteurs multimédia dans un espace 3D. Tel que mentionné ci-dessus, la plupart des capteurs multimédia sont du type directionnel. De surcroît, ces capteurs sont plus coûteux et plus spécialisés que les capteurs scalaires. En conséquence, les déploiements aléatoires, qui sont typiques pour les capteurs scalaires, ne sont ni souhaitables ni adéquats pour les capteurs multimédia. A cet effet, nous proposons un modèle optimal de déploiement 3D de capteurs directionnels. Ce modèle vise à déterminer le nombre minimum de capteurs directionnels connectés, leur emplacement et leur configuration, qui sont nécessaires pour couvrir un ensemble de points de contrôle dans un espace 3D donné. La configuration de chaque capteur déployé est déterminée par trois paramètres : la plage de détection, le champ de vision (FoV) et l'orientation. Nous présentons une formulation « Integer Linear Programming » (ILP) pour trouver la solution exacte du problème et aussi, un algorithme glouton capable de trouver une solution approximative (mais efficace) du problème. Nous évaluons également différentes propriétés des solutions proposées par le biais de nombreuses simulations. Avec ces trois articles on a réussi à résoudre, d'une façon à la fois innovatrice et pratique, les problèmes de routage basé sur la QdS pour les RCMSF et le déploiement de capteurs directionnels, qui sont l'objectif principal de notre recherche.----------ABSTRACT A Wireless Sensor Network (WSN) consists of a set of embedded processing units, called sensors, communicating via wireless links, whose main function is the collection of parameters related to the surrounding environment, such as temperature, pressure or the presence/motion of objects. WSN are expected to have many applications in various fields, such as industrial processes, military surveillance, observation and monitoring of habitat, etc. The availability of inexpensive hardware such as CMOS cameras and microphones that are able to ubiquitously capture multimedia content from the environment has fostered the development of Wireless Multimedia Sensor Networks (WMSNs), i.e., networks of wirelessly interconnected devices that allow retrieving video and audio streams, still images, and scalar sensor data. In addition to the ability to retrieve multimedia data, WMSNs will be able to store, process in real time, correlate and fuse multimedia data originated from heterogeneous sources, and perform actions on the environment based on the content gathered. Many applications require the sensor network paradigm to be rethought in view of the need for mechanisms to deliver multimedia content with a certain level of quality of service (QoS). Due to high bandwidth, processing and stringent Qos requirements existing solutions are not feasible for WMSNs. Since the need to minimize the energy consumption has driven most of the research in sensor networks so far, there is a need to create mechanisms to efficiently deliver application-level QoS, and to map these requirements to network-layer metrics such as latency or delay. Additionally, in WSNs, an omnidirectional sensing model is often assumed where each sensor can equally detect its environment in each direction. Instead, multimedia sensors, specially video sensor, are directional sensors. A directional sensor is characterized by its sensing region which can be viewed as a sector in a three-dimensional plane. Therefore, it can only choose one active sector (or direction) at any time instant. Unfortunately, the many methods developed for deploying traditional WSNs cannot directly be used for optimizing and configuring directional WMSNs due to the different parameters involved. Therefore, new optimization models which capture the primary parameters characterizing directional sensors are necessary. The issues aforementioned are crucial challenges for the development of WMSNs. In this thesis, we are interested in the following aspects: routing of heterogeneous data (scalar and multimedia) from the nodes of a WMSN to the sink in order to provide better QoS experience to users; and an optimized deployment of directional sensors of a WMSN in a three-dimensional surface with the objective to cover all the control points as defined in such a space. Our thesis runs through three scientific papers, each addressing a specific problem. In our first paper, we address the problem of data routing based on different QoS metrics in a WMSN. We propose a new protocol AntSensNet, based on the traditional ant-based algorithm. The AntSensNet protocol builds a hierarchical structure on the network before choosing suitable paths to meet various QoS requirements from different kinds of traffic, thus maximizing network utilization, while improving its performance. In addition, AntSensNet is able to use a efficient multipath video packet scheduling in order to get minimum video distortion transmission. In the second paper, we address the problem of connection admission control for WMSNs. With admission control, it is possible to determine whether a network is capable of supporting a new data stream. Without admission control in a WMSN, the network performance will be compromised because the existing resources within the network cannot be enough for all the flows accepted and this will cause many problems such as packet loss and congestion. Taking multiple parameters into account, we propose a novel connection admission control scheme for the multimedia traffic circulating in the network. The proposed scheme is able to determine if a new flow can be admitted in the network considering the current link states and the energy of the nodes. The decision about accepting is taken in a distributed way, without trusting in a central entity to take this decision. In addition, our scheme works like a plug-in, being easily adaptable to any routing and MAC protocols. Our simulation results show the effectiveness of our approach to satisfy QoS requirements of flows and achieve fair bandwidth utilization and low jitter. Finally, in the third paper, we address the problem of optimal deployment of directional sensors in a 3D space. We have already mentioned that conventional methods to deploy omnidirectional sensors are not suitable to deploy directional sensors. To remedy this deficiency, we propose a mathematical model which aims at to determine the minimum number of connected directional multimedia sensor nodes and their configuration, needed to cover a set of control points in a given 3D space. The configuration of each deployed sensor is determined by three parameters: sensing range, field of view and orientation. We present the exact ILP formulation for the problem and an approximate (but computationally efficient) greedy algorithm solution. We also evaluate different properties of the proposed solutions through extensive simulations. Overall, the proposed solutions in this thesis are both innovative and practical. With these three papers, we have been successfully resolved the problems of a QoS-based routing protocol for WMSN and an optimal deployment of directional sensors in a 3D space, which are the components of the main objective of this thesis

Design of implicit routing protocols for large scale mobile wireless sensor networks

Strathclyde theses - ask staff. Thesis no. : T13189Most developments in wireless sensor networks (WSNs) routing protocols address static network scenarios. Schemes developed to manage mobility in other mobile networking implementations do not translate effectively to WSNs as the system design parameters are markedly different. Thus this research focuses on the issues of mobility and scalability in order to enable the full potential of WSNs to self-organise and co-operate and in so doing, meet the requirements of a rich mix of applications. In the goal of designing efficient, reliable routing protocols for large scale mobile WSN applications, this work lays the foundation by firstly presenting a strong case supported by extensive simulations, for the use of implicit connections. Then two novel implicit routing protocols - Virtual Grid Paging (VGP) and Virtual Zone Registration and Paging (VZRP) - that treat packet routing from node mobility and network scalability viewpoints are designed and analysed. Implicit routing exploits the connection availability and diversity in the underlying network to provide benefits such as fault tolerance, overhead control and improvement in QoS (Quality of Service) such as delay. Analysis and simulation results show that the proposed protocols guarantee significant improvement, delivering a more reliable, more efficient and better network performance compared with alternatives.Most developments in wireless sensor networks (WSNs) routing protocols address static network scenarios. Schemes developed to manage mobility in other mobile networking implementations do not translate effectively to WSNs as the system design parameters are markedly different. Thus this research focuses on the issues of mobility and scalability in order to enable the full potential of WSNs to self-organise and co-operate and in so doing, meet the requirements of a rich mix of applications. In the goal of designing efficient, reliable routing protocols for large scale mobile WSN applications, this work lays the foundation by firstly presenting a strong case supported by extensive simulations, for the use of implicit connections. Then two novel implicit routing protocols - Virtual Grid Paging (VGP) and Virtual Zone Registration and Paging (VZRP) - that treat packet routing from node mobility and network scalability viewpoints are designed and analysed. Implicit routing exploits the connection availability and diversity in the underlying network to provide benefits such as fault tolerance, overhead control and improvement in QoS (Quality of Service) such as delay. Analysis and simulation results show that the proposed protocols guarantee significant improvement, delivering a more reliable, more efficient and better network performance compared with alternatives

Foundations and applications of human-machine-interaction

Der vorliegende Tagungsband zur 10. Berliner Werkstatt Mensch-Maschine-Systeme gibt einen Einblick in die aktuelle Forschung im Bereich der Mensch-Maschine- Interaktion. Einen besonderen Fokus stellt das Wechselspiel von Grundlagenforschung und anwendungsbezogener Forschung dar, was sich im breiten Themenspektrum widerspiegelt, welches von theoretischen und methodischen Betrachtungen bis hin zu anwendungsnahen Fragestellungen reicht. Dabei finden Inhalte aus allen Phasen des Forschungsprozesses Beachtung, sodass auch im Rahmen der 10. Berliner Werkstatt MMS wieder sowohl neue Untersuchungskonzepte als auch abschließende Befunde diskutiert werden. Zentrale Themengebiete sind u. a. Fahrer-Fahrzeug-Interaktion, Assistenzsysteme, User Experience, Usability, Ubiquitous Computing, Mixed & Virtual Reality, Robotics & Automation, Wahrnehmungsspezifika sowie Psychophysiologie und Beanspruchung in der Mensch-Maschine-Interaktion.The proceedings of the 10th Berlin Workshop Human-Machine-Systems provide an insight into the current research in the field of human-machine-interaction. The main focus lies on the interplay between basic and applied research, which is reflected in the wide range of subjects: from theoretical and methodological issues to application oriented considerations. Again all stages of the research process are represented in the contributions of the 10th Berlin Workshop HMS. This means new research concepts as well as final results are subject of this volume. Central topics include driver-vehicleinteraction, assistance systems, user experience, usability, ubiquitous computing, mixed and virtual reality, robotics & automation, perception specifics, as well as psychophysiology and workload in human-machine-interaction