Radio Frequency IDentification (RFID) is growing prominence as an automated identification technology able to turn everyday objects into an ad-hoc network of mobile nodes; which can track, trigger events and perform actions. Energy scavenging and backscattering techniques are the foundation of low-cost identification solutions for RFIDs. The performance of these two techniques, being wireless, significantly depends on the underlying communication architecture and affect the overall operation of RFID systems. Current RFID systems are based on a centralized master-slave architecture hindering the overall performance, scalability and usability. Several proposals have aimed at improving performance at the physical, medium access, and application layers. Although such proposals achieve significant performance gains in terms of reading range and reading rates, they require significant changes in both software and hardware architectures while bounded by inherited performance bottlenecks, i.e., master-slave architecture. Performance constraints need to be addressed in order to further facilitate RFID adoption; especially for ultra large scale applications such as Internet of Things. A natural approach is re-thinking the distributed communication architecture of RFID systems; wherein control and data tasks are decoupled from a central authority and dispersed amongst spatially distributed low-power wireless devices. The distributed architecture, by adjusting the tag's reflectivity coefficient creates micro interrogation zones which are interrogated in parallel. We investigate this promising direction in order to significantly increase the reading rates and reading range of RFID tags, and also to enhance overall system scalability. We address the problems of energy-efficient tag singulations, optimal power control schemes and load aware reader placement algorithms for RFID systems. We modify the conventional set cover approximation algorithm to determine the minimal number of RFID readers with minimal overlapping and balanced number of tags amongst them. We show, via extensive simulation analysis, that our approach has the potential to increase the performance of RFID technology and hence, to enable RFID systems for ultra large scale applications. / Thesis (Ph.D, Computing) -- Queen's University, 2011-08-30 23:41:02.937

Binary Sensor Networks are widely used in target tracking and target parameter estimation. It is more computationally and financially efficient than surveillance camera systems. According to the sensing area, binary sensors are divided into disk shaped sensors and line segmented sensors. Different mathematical methods of target trajectory estimation and characterization are applied. In this thesis, we present a mathematical model of target tracking including parameter estimation (size, intrusion velocity, trajectory, etc.) with line segmented sensor networks. Software simulation and hardware experiments are built based on the model. And we further analyze how the quantization noise affects the results.

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

Wireless sensor network (WSN) has become a hot topic lately. By using WSN things that previously were difficult or impossible to measure has now become available. One of the main reasons using WSN for monitoring is to save money by cost optimization and/or increase safety by letting the user knowing the physical status of the monitored structure. This thesis considers four main topics, empirical testing of WSN in harsh environments, antenna designs, antenna measurements and radio environment emulation. The WSN has been tested in train environment for monitoring of ball bearings and inside jet engines to monitor strain of blades and temperatures. In total, two investigations have been performed aboard the train wagon and one in the jet engine. The trials have been successful and provide knowledge of the difficulties with practical WSN applications. The key issues for WSN are robust communication, energy management (including scavenging) and physical robustness. For the applications of WSN in harsh environments antennas has to be designed. In the thesis, two antennas has been designed, one for train environment and one for the receiver in the jet engine. In the train environment, a more isotropic radiation pattern is preferable; hence a small dual layered patch antenna is designed. The antenna is at the limit of being electrically small; hence slightly lower radiation efficiency is measured. For the WSN in the jet engine, a directive patch array is designed on an ultra-thin and flexible substrate. The thin substrate of the antenna causes rather lower radiation efficiency. But the antenna fulfils the requirements of being conformal and directive. In reverberation chambers are used to measure antennas, but there are difficulties to provide a realistic radio environment, for example outdoor or on-body. In this thesis, a large reverberation chamber is designed and verified. It enables measurement between 400 MHz and 3 GHz. Also, a sample selection method is designed to provide a post processing possibilities to emulate the radio environment inside the chamber. The method is to select samples from a data set that corresponds to a desired probability density function. The method presented in this thesis is extremely fast but the implementation of the method is left for future research. / WISENET / WiseJet

In traditional Wireless Sensor network's (WSN's), the sink is the only unconditionally trusted authority. If the sink is not connected to the nodes for a period of time then the network is considered as unattended. In Unattended Wireless Sensor Network (UWSN), a trusted mobile sink visits each node periodically to collect data. This network differs from the traditional multi hop wireless sensor networks where the nodes close to the sink deplete their power earlier than the other nodes. An UWSN can prolong the life time of the network by saving the battery of the nodes and also it can be deployed in environments where it is not practical for the sink to be online all the time. Saving data in the memory of the nodes for a long time causes security problems due to the lack of tamper-resistant hardware. Data collected by the nodes has to be secured until the next visit of the sink. Securing the data from an adversary in UWSN is a challenging task. We present two non-cryptographic algorithms (DS-PADV and DS-RADV) to ensure data survivability in mobile UWSN. The DS-PADV protects against proactive adversary which compromises nodes before identifying its target. DS-RADV makes the network secure against reactive adversary which compromises nodes after identifying the target. We also propose a data authentication scheme against a mobile adversary trying to modify the data. The proposed data authentication scheme uses inexpensive cryptographic primitives and few message exchanges. The proposed solutions are analyzed both mathematically and using simulations proving that the proposed solutions are better than the previous ones in terms of security and communication overhead.

In this thesis a Proactive Risk-Aware Robotic Sensor Network (RSN) is proposed for the application of Critical Infrastructure Protection (CIP). Each robotic member of the RSN is granted a perception of risk by means of a Risk Management Framework (RMF). A fuzzy-risk model is used to extract distress-based risk features and potential intrusion-based risk features for CIP. Detected high-risk events invoke a fuzzy-auction Multi-Robot Task Allocation (MRTA) algorithm to create a response group for each detected risk. Through Evolutionary Multi-Objective (EMO) optimization, a Pareto set of optimal robot configurations for a response group will be generated using the Non-Dominating Sorting Genetic Algorithm II (NSGA-II). The optimization objectives are to maximize sensor coverage of essential spatial regions and minimize the amount of energy exerted by the response group. A set of non-dominated solutions are produced from EMO optimization for a decision maker to select a single response. The RSN response group will re-organize based on the specifications of the selected response.

Sensor failures or oversupply in wireless sensor networks (WSNs), especially initial random deployment, create both spare sensors (whose area is fully covered by other sensors) and sensing holes. We envision a team of robots to relocate sensors and improve their area coverage. Existing algorithms, including centralized ones and the only localized G-R3S2, move only spare sensors and have limited improvement because non-spare sensors, with area coverage mostly overlapped by neighbour sensors, are not moved, and additional sensors are deployed to fill existing holes. We propose a localized algorithm, called Localized Ant-based Sensor Relocation Algorithm with Greedy Walk (LASR-G), where each robot may carry at most one sensor and makes decision that depends only on locally detected information. In LASR-G, each robot calculates corresponding pickup or dropping probability, and relocates sensor with currently low coverage contribution to another location where sensing hole would be significantly reduced. The basic algorithm optimizes only area coverage, while modified algorithm includes also the cost of robot movement. We compare LASR-G with G-R3S2, and examine both single robot and multi robots scenarios. The simulation results show the advantages of LASR-G over G-R3S2.

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

Wireless sensor networks (WSNs) are a valuable technology to support a huge range of applications spanning from military to commercial, such as battlefield surveillance, habitat monitoring, forest fire detection, disaster salvage, and inventory control management. It has the capability to reveal previously unobservable phenomena in the physical world and significant flexibility of installation and manipulation. The major challenges of WSNs design come from the requirements of energy constraint, distributed control and scalability. In this thesis we studied three topics on WSNs. The first one was energy-efficient medium access control (MAC) protocol design. We proposed a MAC protocol which schedules the send and receive times for all nodes within the network. As all nodes only wake up when they send or receive, significant energy is saved by reducing idle listening, collisions and overhearing. And we evaluated the protocol performance by using the GloMoSim simulator. The second topic was about distributed transmission power control of wireless sensor nodes. We proposed a simple scheme which employs request-to-send (RTS) and clear-to-send (CTS) frames to exchange channel gain information, based on which concurrent senders determine their own transmission power without a central controller to coordinate them. Simulation results showed that our scheme can save 30% to 50% of the energy, and also reduce transmissionlatency.The third topic was on event detection. Due to the fact that wireless sensor nodes are spatially distributed throughout the area of interest, this application has to been implemented in distributed form. We proposed a scheme which does not need a pre-designated fusion node, and this greatly improves network scalability. We provided close-form expressions to estimate the probabilities of detection failure and false alarm, and validated them by extensive simulation.

In wireless sensor network, we usually need to combine the information gathered from multiple sensors to detect an event. To answer this question we present a new type of query, Geo-Range query. This query reports the geographic points where the average value of nearby sensors are greater than certain threshold. To perform this query, we developed two fast, efficient algorithms. The Brute-Force algorithm use exhaustive method to enumerate all possible values, which takes O(n^3) running time. The Sweep-Line algorithm applies a conceptual line sweeping through the plane. The sweep-line moves through the plane and keeps tracking all the sensor points encountered. The algorithm takes O( n^2 \log n ) running time, while it still gives exact solution to the problem. We implement and simulate our algorithms in Visual Basic.Net.