Doctor of Philosophy (PhD) / Sensor networks have great potential to be employed in mission critical situations like battlefields but also in more everyday security and commercial applications such as building and traffic surveillance, habitat monitoring and smart homes etc. However, wireless sensor networks pose unique security challenges. While the deployment of sensor nodes in an unattended environment makes the networks vulnerable to a variety of potential attacks, the inherent power and memory limitations of sensor nodes makes conventional security solutions unfeasible. Though there has been some development in the field of sensor network security, the solutions presented thus far address only some of security problems faced. This research presents a security framework WSNSF (Wireless Sensor Networks Security Framework) to provide a comprehensive security solution against the known attacks in sensor networks. The proposed framework consists of four interacting components: a secure triple-key (STKS) scheme, secure routing algorithms (SRAs), a secure localization technique (SLT) and a malicious node detection mechanism. Singly, each of these components can achieve certain level of security. However, when deployed as a framework, a high degree of security is achievable. WSNSF takes into consideration the communication and computation limitations of sensor networks. While there is always a trade off between security and performance, experimental results prove that the proposed framework can achieve high degree of security with negligible overheads.

Mobile sinks are vital in many wireless sensor applications for efficient data collection, data querying, and localized sensor reprogramming. Mobile sinks prolong the lifetime of a sensor network. However, when sensor networks with mobile sinks are deployed in a hostile environment, security became a critical issue. They become exposed to varieties of malicious attacks. Thus, anti threats schemes and security services, such as mobile sink?s authentication and pairwise key establishment, are essential components for the secure operation of such networks. Due to the sensors, limited resources designing efficient security schemes with low communication overhead to secure communication links between sensors and MS (Mobile Sink) is not a trivial task. In addition to the sensors limited resources, sink mobility required frequent exchange of cryptography information between the sensors and MS each time the MS updates its location which imposes extra communication overhead on the sensors. In this dissertation, we consider a number of security schemes for WSN (wireless sensor network) with MS. The schemes offer high network?s resiliency and low communication overhead against nodes capture, MS replication and wormhole attacks. We propose two schemes based on the polynomial pool scheme for tolerating nodes capture: the probabilistic generation key pre-distribution scheme combined with polynomial pool scheme, and the Q-composite generation key scheme combined with polynomial pool scheme. The schemes ensure low communication overhead and high resiliency. For anti MS replication attack scheme, we propose the multiple polynomial pools scheme that provide much higher resiliency to MS replication attack as compared to the single polynomial pool approach. Furthermore, to improve the network resiliency against wormhole attack, two defensive mechanisms were developed according to the MS mobility type. In the first technique, MS uses controlled mobility. We investigate the problem of using a single authentication code by sensors network to verify the source of MS beacons, and then we develop a defensive approach that divide the sensor network into different authentication code?s grids. In the second technique, random mobility is used by MS. We explore the use of different communication channels available in the sensor hardware combined with polynomial pool scheme.

Doctor of Philosophy (PhD) / Sensor networks have great potential to be employed in mission critical situations like battlefields but also in more everyday security and commercial applications such as building and traffic surveillance, habitat monitoring and smart homes etc. However, wireless sensor networks pose unique security challenges. While the deployment of sensor nodes in an unattended environment makes the networks vulnerable to a variety of potential attacks, the inherent power and memory limitations of sensor nodes makes conventional security solutions unfeasible. Though there has been some development in the field of sensor network security, the solutions presented thus far address only some of security problems faced. This research presents a security framework WSNSF (Wireless Sensor Networks Security Framework) to provide a comprehensive security solution against the known attacks in sensor networks. The proposed framework consists of four interacting components: a secure triple-key (STKS) scheme, secure routing algorithms (SRAs), a secure localization technique (SLT) and a malicious node detection mechanism. Singly, each of these components can achieve certain level of security. However, when deployed as a framework, a high degree of security is achievable. WSNSF takes into consideration the communication and computation limitations of sensor networks. While there is always a trade off between security and performance, experimental results prove that the proposed framework can achieve high degree of security with negligible overheads.

Master of Science / Department of Electrical and Computer Engineering / Balasubramaniam Natarajan / Decentralized sensor networks are collections of individual local sensors that observe a common phenomenon, quantize their observations, and send this quantized information to a central processor (fusion center) which then makes a global decision about the phenomenon. Most of the existing literature in this field consider only the data fusion aspect of this problem, i.e., the statistical hypothesis testing and optimal combining of the information obtained by the local sensors. In this thesis, we look at both the data detection and the data fusion aspects of the decentralized sensor networks. By data detection, we refer to the communication problem of transmitting quantized information from the local sensors to the fusion center through a multiple access channel. This work first analyzes the data fusion problem in decentralized sensor network when the sensor observations are corrupted by additive white gaussian noise. We optimize both local decision rules and fusion rule for this case. After that, we consider same problem when the observations are corrupted by correlated gaussian noise. We propose a novel parallel genetic algorithm which simultaneously optimizes both the local decision and fusion rules and show that our algorithm matches the results from prior work with considerably less computational cost. We also demonstrate that, irrespective of the fusion rule, the system can provide equivalent performance with an appropriate choice of local decision rules. The second part of this work analyzes the data detection problem in distributed sensor networks. We characterize this problem as a multiple input multiple output (MIMO) system problem, where the local sensors represent the multiple input nodes and the fusion center(s) represent the output nodes. This set up, where the number of input nodes (sensors) is greater than the number of output nodes (fusion center(s)), is known as an overloaded array in MIMO terminology. We use a genetic algorithm to solve this overloaded array problem.

Wireless sensor networks (WSNs) are becoming increasingly pervasive in a number of applications. Due to the nature of WSNs, one of their biggest constraints is limited node energy. As WSNs grow in popularity, the prevalent issue remains to keep wireless sensor nodes alive for as long as possible, or risk disrupting the network. This dissertation develops a model based on the principles of game theory to improve the energy efficiency of wireless sensor nodes and increase the network lifetime by influencing the way routing takes place. The benefit of this model is a routing algorithm that is easily implementable and increases network lifetime by improving energy efficiency in the network. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2015

Wireless sensor networks (WSNs) are becoming increasingly pervasive in a number of applications. Due to the nature of WSNs, one of their biggest constraints is limited node energy. As WSNs grow in popularity, the prevalent issue remains to keep wireless sensor nodes alive for as long as possible, or risk disrupting the network. This dissertation develops a model based on the principles of game theory to improve the energy efficiency of wireless sensor nodes and increase the network lifetime by influencing the way routing takes place. The benefit of this model is a routing algorithm that is easily implementable and increases network lifetime by improving energy efficiency in the network. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2015

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / This paper presents the design and development of a fluorometry sensor network with LED excitation. The design of the electronics in junction with the capability of LED excitation will significantly reduce the size and costs of the flrorometer units. The coverage and effectiveness of the sensing and monitoring capability will also be greatly enhanced by the addition of the wireless networks.

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / There are a number of telemetry applications where it would be helpful to have networks of sensors that could autonomously discover their connectivity, and dynamically reconfigure themselves during use. A number of research groups have developed wireless ad-hoc sensor network systems. This paper reviews the state-of-the-art in wireless ad-hoc networks, examining the features, assumptions, limitations and unique attributes of some of the more popular solutions to this problem.

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / This paper explains the development of a wireless network system implemented to streamline grocery store checkout procedures. The design employs a wireless telemetry network consisting of a base station and wireless motes (Micaz MPR2400) that will be located on certain aisles, and attached to shopping carts. This system allows customers to scan items while they shop and uses cashiers for payment purposes only. The objective is to minimize the amount of processing performed by cashiers in order to reduce waiting times in line. The system was tested in a simulation environment and waiting times were reduced by 65%.

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / Industrial wireless sensor networks can be designed to meet the strict requirements of specific distributed applications. Emerging standards have enabled the development of low-cost, lowpower sensor nodes that are quickly becoming a commodity, enabling the realization of efficient and reliable data acquisition and telemetry in many systems. Moreover, new and exciting possibilities arise from the distributed computing power of the sensor nodes, the ability to monitor and aggregate data across large arrays of sensors, and the ability to model dynamic and rugged environments that were previously beyond the reach of traditional data acquisition and telemetry systems.