As the number of Internet-connected devices rapidly grows, it has become ever more challenging to develop and maintain purpose-made tightly integrated distributed embedded systems. Instead, the Internet of Things (IoT) approach, based on standardized interfaces and open communication protocols, enables support for various applications with the possibility of extension to provide additional services that were not necessarily available at the initial deployment.This thesis presents methods and tools for the development of standard-based Web services for the Internet of Things. Some of the key challenges in using Web services on resource-constrained devices are due to the overhead of the communication protocols, which leads to the need for greater network bandwidth, processing power, and memory usage. A common solution to these problems is to use gateways that translate between the protocols used on one end of the connection (i.e. low-capability devices) and those on the other end (i.e. powerful Web servers). However, this increases the overall complexity of the system. The work presented herein answers the following research questions: 1) Is it feasible to deploy standard Web services on IoT systems without using application layer gateways? 2) What are the trade-offs in using Web services for end-to-end interoperability of resource-constrained embedded systems? 3) What levels of efficiency and functionality can be achieved using binary coding schemes for XML data exchange?The research questions are tested by building and evaluating several prototype IoT systems. These evaluations show that the use of Web services requires more powerful hardware (i.e. CPU and RAM) and a larger form factor in exchange for better interoperability compared to the use of ad hoc application protocols. The main challenge in employing embedded Web services is the large size of the messages, which is due to the use of verbose data formats such as XML. Although it is shown that it is possible to deploy XML-based Web services on low-capability devices without application layer gateways, this approach has severe performance limitations. Using the Efficient XML Interchange (EXI) binary coding scheme overcomes some of these limitations by substantially reducing the size of the XML messages. The main outcome of this thesis is the design and implementation of a software toolkit, called EXIP, for building EXI-based embedded Web services.The trade-offs in the use of embedded Web services are likely to change in the near future as the importance of application layer interoperability increases and IoT devices become faster, more energy efficient, and equipped with more memory. The dominating importance of interoperability can be seen in highly heterogeneous systems such as energy management systems (i.e. smart grids), where embedded Web services are already in use today. With this in mind, future research directions and extensions of this work include the development of performance optimization strategies for the EXIP toolkit to foster the expansion of embedded Web services to an even wider range of IoT applications. / Godkänd; 2014; 20140909 (rumkyu); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Rumen Kyusakov Ämne: Industriell elektronik/Industrial Electronics Avhandling: Efficient Web Services for End-To-End Interoperability of Embedded Systems Opponent: Dr Frank Golatowski, Institute of Applied Microelements and CE, University of Rostock, Rostock-Warnemüende, Germany Ordförande: Biträdande professor Jens Eliasson, EISLAB, Institutionen för system- och rymdteknik, Luleå tekniska universitetet, Luleå Tid: Tisdag den 4 november 2014, kl. 13:00 Plats: A109, Luleå tekniska universitet / Embeddable EXI implementation in C, Architecture for Service-Oriented Process – Monitoring and Control, Arrowhead

Although Wireless Sensor Networks (WSNs) have found a niche in numerous applications, they are constrained by numerous factors. One of these important factors is security in WSNs. There are various types of security attacks that WSNs are susceptible to. The focus of this study is centred on Sybil attacks, a denial of service attack. In this type of attack, rogue nodes impersonate valid nodes by falsely claiming to possess authentic identities, thereby rendering numerous core WSN operations ineffective. The diverse nature of existing solutions poses a difficult problem for system engineers wanting to employ a best fit countermeasure. This problem is the largely unanswered question posed to all system engineers and developers alike whose goal is to design/develop a secure WSN. Resolving this dilemma proves to be quite a fascinating task, since there are numerous factors to consider and more especially one cannot assume that every application is affected by all identified factors. A framework methodology presented in this study addresses the abovementioned challenges by evaluating countermeasure effectiveness based on theoretical and practical security factors. Furthermore, a process is outlined to determine the application’s engineering requirements and the framework also suggests what security components the system engineer ought to incorporate into the application, depending on the application’s risk profile. The framework then numerically aligns these considerations, ensuring an accurate and fairly unbiased best fit countermeasure selection. Although the framework concentrates on Sybil countermeasures, the methodology can be applied to other classes of countermeasures since it answers the question of how to objectively study and compare security mechanisms that are both diverse and intended for different application environments. The report documents the design and development of a comparative framework that can be used to evaluate countermeasures against Sybil attacks in wireless sensor networks based on various criteria that will be discussed in detail. This report looks briefly at the aims and description of the research. Following this, a literature survey on the body of knowledge concerning WSN security and a discussion on the proposed methodology of a specific design approach are given. Assumptions and a short list of factors that were considered are then described. Metrics, the taxonomy for WSN countermeasures, the framework and a formal model are developed. Risk analysis and the best fit methodology are also discussed. Finally, the results and recommendations are shown for the research, after which the document is concluded. / Dissertation (MEng)--University of Pretoria, 2011. / Electrical, Electronic and Computer Engineering / unrestricted

Las aplicaciones para redes de sensores inalámbricas, o Wireless Sensor Networks (WSNs), han mostrado un crecimiento significativo en los últimos años. Actualmente constituyen una alternativa tecnológica interesante para el desarrollo de aplicaciones que requieren monitorizar constantemente el estado de cualquier variable relacionada con escenarios de diversos ámbitos. Si las aplicaciones detectan cambios en los valores de dichas variables, pueden activar la ejecución de acciones preventivas que ayuden a restaurar las condiciones normales del entorno monitorizado. Algunos ejemplos de aplicaciones que se pueden beneficiar de las WSNs son las aplicaciones para la detección de eventos, entre las que se incluye la detección de incendios forestales. Este tipo de aplicaciones ha recibido mucha atención recientemente, ya que cada año se presentan incendios forestales que arrasan con una gran cantidad de flora y fauna, provocando grandes pérdidas económicas y humanas. Otra área de gran interés es la utilización de redes de sensores en la detección de propagación de gases. Estas aplicaciones tienen la finalidad de evitar tragedias, sobre todo en el caso de la propagación de gases peligrosos. Por otra parte, las redes de sensores también han sido utilizadas en la detección y seguimiento de objetivos e intrusos. Con estas aplicaciones es posible vigilar áreas restringidas, ya sea por el servicio que proporcionan o por los objetos de valor que puedan contener. Para implementar eficientemente aplicaciones que utilicen redes de sensores inalámbricas en la detección de eventos de propagación de fuego y gas, así como para detectar y realizar el seguimiento de intrusos, es conveniente utilizar mecanismos que permitan detectar los eventos críticos de forma correcta e inmediata, de tal manera que se informe y actúe en tiempo real para llevar a cabo las acciones necesarias. En esta tesis doctoral se propone una arquitectura para redes de sensores que permita detectar en tiempo real la presencia de eventos que alteren el estado normal del entorno monitorizado, actuando a continuación convenientemente. / Lino Ramírez, C. (2012). Diseño de una arquitectura para redes de sensores con soporte para aplicaciones de detección de eventos [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/15152 / Palancia

The use of a mobile charger (MC) is a popular method to restore energy in wireless rechargeable sensor networks(WRSN), whose effectiveness depends critically on the recharging strategy employed by the MC. In this thesis, we propose a novel on-line recharging mechanism strategy, called Continuous Local Learning (CLL), which predicts the current energy level of the sensor nodes and dynamically updates the schedule to visit the nodes before their batteries get depleted. The strategy is based on simple computations done by the MC with little memory requirements, and the communication is strictly local (between the MC and neighbouring nodes). In spite of its simplicity, this strategy was experimentally shown to be highly effective in keeping the network perpetually operating, ensuring that the number of sensing holes (i.e., non-operational sensors due to battery depletion) and their duration are very small at any time, and achieving immortality (i.e., no node ever becoming nonoperational) under many settings even in large networks. We also studied the flexibility of CLL under a variety of network parameters, showing its applicability in various contexts. We particularly focused on network size, data rate, sensors’ battery-capacity, and speed of the MC, and studied their impact on operational size and disconnection time under a wide range of values. The experiments indicate the fact that the effectiveness of CLL holds under all considered settings. We then compared the proposed solution with the popular class of static strategies since they share with CLL the features of simplicity, strict local communication and small memory and computational requirements. Experimental results showed that CLL outperforms these strategies in effectiveness. Not only is the number of sensors that are operational at any time higher under CLL, but the average duration of a sensing hole is also significantly lower. Finally, we studied the adaptability of CLL to a network’s sudden changes, in particular changes in data rate, which we call spikes. We studied the impact of spikes parameters on the performance of CLL. Experimental results showed that CLL is capable of reacting and adapting to these sudden changes with only a slight increase in non-operational size and disconnection time.

This diploma thesis is focused on research of localization algorithms. Each developed localization algorithms are generally application specific. Because of application requirements diversity, many variants of localization algorithms exist. In case of finding appropriate localization algorithm for concrete application usability, existence of real condition simulation environment is useful. Development of this simulation environment was made simultaneously with both localization algorithms. At first, survey of available localization technic was performed and their summary was listed. Further work was aimed on research of two localization algorithms. Both of them use triangulation mechanism to determine unknown node position. This mechanism is based on measurement of distance to three reference points with known position. It would seem that both algorithms are similar, but simulation shows their difference and presents their suitability for diverse conditions.

The diploma thesis is focused on two localization algorithms, iterative algorithm, and a linked algorithm simulated in MATLAB. Further, the investigation of the influence of input errors on the errors in localization of sensor nodes examined algorithms and explore possible relationships between the input errors and localization errors. Subsequently are submitted possible ways to optimize and their results.

This thesis describes the design of wireless sensor network (WSN) for monitoring of people and objects in a building. The work deals with issues of localization and tracking in sensor networks and algorithm implementation to sensor nodes. It also contains a description of the aplication requirements. These requirements form the basis for the proposal. The hardware part of the network consists of sensor nodes IRIS from Crossbow company. The work describes the properties of these nodes. Next part deals with of propagation model and design of the localization algorithm. The paper also describes the communication in the network. The thesis also includes a practical realization of the proposed network, the localization system and its testing. In the work is included a CD with the building schematic in AutoCAD and with source code of created applications.

Theme of the thesis is research and possibility of using GPS system from localization in wireless sensor network. Paper deals with the accuracy and energy consumption of GPS localization. Thesis also solve using of localization in local anchor system. Theoretical part describes IEEE 802.15.4 standard, capability of used nodes and describe ways how to use RSSI value to resolve location

This thesis deals with the agent platforms for wireless sensor networks. Wireless sensor networks together with the software and hardware tools used for their programming are introduced at the beginning of the thesis. The following chapter is devoted to the agents and their possible usage in wireless sensor networks. Two agent platforms Agilla and WSageNt are presented in the rest of the thesis. The end of the thesis presents the main differences between both platforms.

This dissertation is directed towards improving the performance of 5G Wireless Fronthaul Networks and Wireless Sensor Networks, as measured by reliability, fault recovery time, energy consumption, efficiency, and security of transmissions, beyond what is achievable with conventional error control technology. To achieve these ambitious goals, the research is focused on novel applications of networking techniques, such as Diversity Coding, where a feedforward network design uses forward error control across spatially diverse paths to enable reliable wireless networking with minimal delay, in a wide variety of application scenarios. These applications include Cloud-Radio Access Networks (C-RANs), which is an emerging 5G wireless network architecture, where Remote Radio Heads (RRHs) are connected to the centralized Baseband Unit (BBU) via fronthaul networks, to enable near-instantaneous recovery from link/node failures. In addition, the ability of Diversity Coding to recover from multiple simultaneous link failures is demonstrated in many network scenarios. Furthermore, the ability of Diversity Coding to enable significantly simpler and thus lower-cost routing than other types of restoration techniques is demonstrated. Achieving high throughput for broadcasting/multicasting applications, with the required level of reliability is critical for the efficient operation of 5G wireless infrastructure networks. To improve the performance of C-RAN networks, a novel technology, Diversity and Network Coding (DC-NC), which synergistically combines Diversity Coding and Network Coding, is introduced. Application of DC-NC to several 5G fronthaul networks, enables these networks to provide high throughput and near-instant recovery in the presence of link and node failures. Also, the application of DC-NC coding to enhance the performance of downlink Joint Transmission-Coordinated Multi Point (JT-CoMP) in 5G wireless fronthaul C-RANs is demonstrated. In all these scenarios, it is shown that DC-NC coding can provide efficient transmission and reduce the resource consumption in the network by about one-third for broadcasting/multicasting applications, while simultaneously enabling near-instantaneous latency in recovery from multiple link/node failures in fronthaul networks. In addition, it is shown by applying the DC-NC coding, the number of redundant links that uses to provide the required level of reliability, which is an important metric to evaluate any protection system, is reduced by about 30%-40% when compared to that of Diversity Coding. With the additional goal of further reducing of the recovery time from multiple link/node failures and maximizing the network reliability, DC-NC coding is further improved to be able to tolerate multiple, simultaneous link failures with less computational complexity and lower energy consumption. This is accomplished by modifying Triangular Network Coding (TNC) and synergistically combining TNC with Diversity Coding to create enhanced DC-NC (eDC-NC), that is applied to Fog computing-based Radio Access Networks (F-RAN) and Wireless Sensor Networks (WSN). Furthermore, it is demonstrated that the redundancy percentage for protecting against n link failures is inversely related to the number of source data streams, which illustrates the scalability of eDC-NC coding. Solutions to enable synchronized broadcasting are proposed for different situations. The ability of eDC-NC coding scheme to provide efficient and secure broadcasting for 5G wireless F-RAN fronthaul networks is also demonstrated. The security of the broadcasting data streams can be obtained more efficiently than standardized methods such as Secure Multicasting using Secret (Shared) Key Cryptography.