Security and trust are two interdependent concepts and are often used interchangeably when defining a secure wireless sensor network (WSN) system. However, security is different from trust in that, it assumes no node is trustworthy and requires ongoing authentication using sophisticated protocols leading to high communication and computation overheads. This makes the traditional cryptographic security tools hard, if not impossible, to be used in wireless sensor networks that are severely resource constrained. Trust on the other hand is the exact opposite of security in that any node can interact with any other and requires no authentication and unwrapping of hidden keys to carry on with their business and hence carries zero overhead. However, this leads to the miss-use and abuse of networks causing loss and damage to the owners of the networks. This thesis focuses on developing novel methods for modelling and managing trust that enable WSN to be secure while significantly reducing computing and communication overheads. Although researchers have been studying the problem of trust modelling and management in wireless sensor networks for over a decade, their focus was on the trust associated with routing messages between nodes (communication trust). However, wireless sensor networks are mainly deployed to sense the world and report data, both continuous and discrete. However, there are no methods in the literature that focus on the trust associated with misreporting data (data trust). In this thesis, we model the trust associated with the integrity of the data, and propose methods to combine the data trust with the communication trust to infer the total trust. Bayesian probabilistic approach is used to model and manage trust. A new risk assessment algorithm for establishing trust in wireless sensor networks based on the quality of services characteristics of sensor nodes, using the traditional weighting approach is introduced. Then a Beta distribution is used to model communication trust (due to its binary nature) and determine the weights in terms of the Beta distribution parameters to probabilistically combine direct and indirect trust. The thesis extends the Bayesian probabilistic approach to model data trust for cases when the sensed data is continuous. It introduces the Gaussian trust and reputation system to that accounts for uncertain characteristics of sensor data. Finally we introduce a Bayesian fusion algorithm to combine the data trust and communication trust to infer the overall trust between nodes. Simulation results are presented to demonstrate how the models accurately classify different nodes as being trustworthy or not based on their reliability in sensor reporting and routing functions.

Doctor of Philosophy(PhD) / 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 networks

Security and trust are two interdependent concepts and are often used interchangeably when defining a secure wireless sensor network (WSN) system. However, security is different from trust in that, it assumes no node is trustworthy and requires ongoing authentication using sophisticated protocols leading to high communication and computation overheads. This makes the traditional cryptographic security tools hard, if not impossible, to be used in wireless sensor networks that are severely resource constrained. Trust on the other hand is the exact opposite of security in that any node can interact with any other and requires no authentication and unwrapping of hidden keys to carry on with their business and hence carries zero overhead. However, this leads to the miss-use and abuse of networks causing loss and damage to the owners of the networks. This thesis focuses on developing novel methods for modelling and managing trust that enable WSN to be secure while significantly reducing computing and communication overheads. Although researchers have been studying the problem of trust modelling and management in wireless sensor networks for over a decade, their focus was on the trust associated with routing messages between nodes (communication trust). However, wireless sensor networks are mainly deployed to sense the world and report data, both continuous and discrete. However, there are no methods in the literature that focus on the trust associated with misreporting data (data trust). In this thesis, we model the trust associated with the integrity of the data, and propose methods to combine the data trust with the communication trust to infer the total trust. Bayesian probabilistic approach is used to model and manage trust. A new risk assessment algorithm for establishing trust in wireless sensor networks based on the quality of services characteristics of sensor nodes, using the traditional weighting approach is introduced. Then a Beta distribution is used to model communication trust (due to its binary nature) and determine the weights in terms of the Beta distribution parameters to probabilistically combine direct and indirect trust. The thesis extends the Bayesian probabilistic approach to model data trust for cases when the sensed data is continuous. It introduces the Gaussian trust and reputation system to that accounts for uncertain characteristics of sensor data. Finally we introduce a Bayesian fusion algorithm to combine the data trust and communication trust to infer the overall trust between nodes. Simulation results are presented to demonstrate how the models accurately classify different nodes as being trustworthy or not based on their reliability in sensor reporting and routing functions.

<p>X3 C is a Swedish company which develops a world wide good tracking system by using ARFID </p><p>tags placed on every item which has to be delivered and base stations as gateway in a wireless </p><p>sensor network. The requirement of a long lifespan of their ARFID tags made it difficult to </p><p>implement security. Firstly an evaluation of possible security mechanisms and their power </p><p>consumption was done by measuring the avalanche effect and character frequency of the sym- </p><p>metric algorithms Blowfish, RC2 and XTEA. Secondly, the required CPU time which is needed </p><p>by each algorithm for encrypting a demo plaintext, was measured and analyzed. Summariz- </p><p>ing both analysis, the XTEA algorithm, run in CBC mode, is the recommendation for the XC </p><p>ARFID tags. The testing processes and the results are presented in detail in this thesis.</p>

<p>Wireless Sensor Networks have to be very flexible and self-organizing, providing an ease way to be deployed. This feature is required due to a wide variety of possible applications and deployment scenarios in which they can be used. They can support different kinds of tools and applications in distinct areas, such as in agriculture, military, health care, home or factory automation, among other. </p><p> An assisted living system supported by a WSN is presented in this work. The main feature of this system is to locate and track inhabitant’s behaviour. The system has been implemented using Mica2 Motes, which were placed in different rooms in a house. In order to make the use of the WSN easier, this project investigated and used a middleware called TinyDB, which represents a key technology to improve the usability of WSN.</p>

No description available.

The purpose of the thesis is to design and develop a network of automated, distributed, living cell-based sensors, called CytoSensors. Their main role is to detect a variety of biological and chemical toxins. The system is designed to help researchers to carry out multitude of experiments, in order to build a practical knowledge base in toxin detection. The network is developed in accordance with industry standards, to be used and deployed for prevention in inhospitable environments such as battlefields, toxic urban locations or polluted agricultural regions. The sensor is composed of a processing unit (processor and memory), an archiving unit (permanent data storage), a communication unit, input devices attached to a data acquisition unit, and control devices. The CytoSensor is specifically designed to acquire and analyze visual information about the living cells: hence cameras are used as input devices and frame grabbers are used as the digitizers. The control devices are additional external devices developed to help control and automate the process of data acquisition: they comprise light intensity control USB boards to provide the correct amount of light to view the cells, touch panels for user-instrument interaction, and bar code readers to identify vials and experiments. The software, on the other hand, is a complex mosaic of different elements, each of which has a specific task to accomplish. These building blocks include the real-time acquisition, archiving, networking, processing, modelling, sensor output presentation and user interfaces. Our goal is to develop, integrate and optimize all these components to produce a viable and working device. The prototypes evolved from an offline, portable sensor equipped with a single high-resolution CCD camera and high-quality optics, to distributed online sensors with multiplexed CCD cameras and affordable optics. The acquisition board digitizes in real time the images from one to twelve multiplexed high resolution cameras. Several operational requirements must be met. First, a fault-tolerant and stable control over the input devices and control devices must be provided. Secondly, acquisition timing errors should be minimized as a trade-off between performance and the use of a low-cost, general-purpose, industry-standard operating system such as Microsoft Windows NT. Finally, in order to reduce development time and increase code reusability, a common abstraction layer is designed to provide for flexible use with various types of digitizers and cameras. As part of a distributed detection network, each sensor is able to exchange data with other "trusted" sensors and users, and to allow remote control of certain tasks. The sensor may be seen as a node capable of transmitting and receiving acquired or processed data to a distant device (another sensor, a workstation or a PDA) for visualization, inspection and decision-making by a front-end user. Each node on the network provides a set of complementary services including data acquisition, data processing, communication and system. The mandatory system service monitors the local system performance and manages data archiving. The communication service connects the various services on the network by enabling message-passing, file transfer and caching. The sensor network integrates a lightweight, interoperable and flexible RPC (Remote Procedure Call) protocol to achieve real-time control and monitoring of these distributed resources. A reliable embedded database system is used to store metadata bound to acquired and processed images. This database is also used to maintain information on neighbor nodes, and to check access credentials of available local services. Finally, by adding store-and-forward messaging capabilities, the application can be extended to work in wireless and mobile networks. / Graduation date: 2003

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Busby N. O. Attoh-Okine, Dept. of Civil & Environmental Engineering. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 148-154).

Thesis (Ph. D.)--Drexel University, 2005. / Includes abstract and vita. Includes bibliographical references (leaves 109-114).