Dissertations / Theses: 'Querying (Computer science). Wireless sensor networks'

1

Abuaitah, Giovani Rimon. "Trusted Querying over Wireless Sensor Networks and Network Security Visualization." Wright State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=wright1240163119.

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Jin, Guang. "Towards Spatial Queries over Phenomena in Sensor Networks." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/JinG2009.pdf.

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Lin, Zhifeng, and 林志锋. "Advanced spatial queries in wireless ad hoc networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43224295.

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Lin, Zhifeng. "Advanced spatial queries in wireless ad hoc networks." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43224295.

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Chiu, Tsz Wai. "WinyDB : collaboratively querying sensor networks through handheld devices /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CSED%202008%20CHIUT.

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Salatas, Vlasios. "Object tracking using wireless sensor networks." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Sep%5FSalatas.pdf.

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Thesis (M.S. in Computer Science)--Naval Postgraduate School, September 2005.
Thesis Advisor(s): Gurminder Singh, Arijit Das. Includes bibliographical references (p. 271-273). Also available online.

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Anantharaju, Srinath. "Resilient Data Aggregation in Wireless Sensor Networks." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-07282005-161557/.

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Sensor nodes are low-cost and low-power devices that are prone to node compromises, communication failures and malfunctioning of sensing hardware. As a result, some nodes may report outlying data values, introducing significant deviations in the aggregated sensor readings. This thesis presents a practical resilient outlier detection technique to filter out the influence of the outlying data reported by faulty or compromised nodes. The proposed outlier detection algorithm is based on event localization using minimum mean squared error (MMSE) estimation combined with threshold-based consistency checking to detect outliers. Data aggregation is one of the key techniques commonly used to develop lightweight communication protocols applicable to wireless sensor networks. The proposed approach handles localization of multiple events by grouping the sensor readings into spatially correlated clusters and performing an event-centric detection of outliers. In the entire process of data aggregation, the outlier detection technique fits as a preprocessing stage for reducing the effect of outliers on the aggregated result. Suitable extensions to the basic outlier detection algorithm are proposed to effectively apply the algorithm to both centralized and decentralized sensor network architectures. This thesis further includes studies that test the effectiveness of the proposed approach, including the detection rate, the false positive rate, degree of damage and the resilience to malicious readings introduced by the attackers. The experimental results show that on average the proposed approach detects as high as 80-90% of the outliers while resulting in 5-15% false positive rate when the network consists of 40-45% outliers. The experiments also show that the extent of damage on the aggregated result is below 50% due to the elimination of outliers before aggregation. Finally, the resilient data aggregation process requires modest computational and memory requirements with zero communication overhead in the centralized case and about 20% overhead in the decentralized settings.

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Alarifi, Abdulrahman S. N. "Security through diversity for wireless sensor networks." Related electronic resource:, 2007. http://proquest.umi.com/pqdweb?did=1342747901&sid=1&Fmt=2&clientId=3739&RQT=309&VName=PQD.

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Bai, Xiaole. "Optimal Connected Coverage for Wireless Sensor Networks." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1259772831.

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Kim, Min Y. "Configuration and management of wireless sensor networks." Thesis, Monterey, California. Naval Postgraduate School, 2005. http://hdl.handle.net/10945/1763.

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Wireless sensor networks (WSNs) are expected to play an essential role in the upcoming age of pervasive computing. As a new research area, there are several open problems that need to be investigated. One such problem is configuration and management of WSNs. To deploy sensors efficiently in a wide area, we need to consider coverage, purpose and geographic situation. By considering these elements, we can make general deployment strategies. Another issue is management of various sensors in wide area. To handle these issues, we need approaches from different view, management levels, WSN functionalities, and management functional areas. In this thesis, I describe some of the key configuration and management problems in WSNs. Then, I present a newly developed application to address these problems.

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Kho, Johnsen. "Decentralised control of wireless sensor networks." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/66078/.

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Wireless sensor networks are receiving a considerable degree of research interest due to their deployment in an increasing number and variety of applications. However, the efficient management of the limited energy resources of such networks in a way that maximises the information value of the data collected is a significant research challenge. To date, most of these systems have adopted a centralised control mechanism, but from a system's perspective this raises concerns associated with scalability, robustness, and the ability to cope with dynamism. Given this, decentralised approaches are appealing. But, the design of efficient decentralised regimes is challenging as it introduces an additional control issue related to the dynamic interactions between the network's interconnected nodes in the absence of a central coordinator. Within this context, this thesis first concentrates on decentralised approaches to adaptive sampling as a means of focusing a node's energy consumption on obtaining the most important data. Specifically, we develop a principled information metric based upon Fisher information and Gaussian process regression that allows the information content of a node's observations to be expressed. We then use this metric to derive three novel decentralised control algorithms for information-based adaptive sampling which represent a trade-off in computational cost and optimality. These algorithms are evaluated in the context of a deployed sensor network in the domain of flood monitoring. The most computationally efficient of the three is shown to increase the value of information gathered by approximately 83%, 27%, and 8% per day compared to benchmarks that sample in a naive non-adaptive manner, in a uniform non-adaptive manner, and using a state-of-the-art adaptive sampling heuristic (USAC) correspondingly. Moreover, our algorithm collects information whose total value is approximately 75% of the optimal solution (which requires an exponential, and thus impractical, amount of time to compute). The second major line of work then focuses on the adaptive sampling, transmitting, forwarding, and routing actions of each node in order to maximise the information value of the data collected in resource-constrained networks. This adds additional complexity because these actions are inter-related, since each node's energy consumption must be optimally allocated between sampling and transmitting its own data, receiving and forwarding the data of other nodes, and routing any data. Thus, in this setting we develop two optimal decentralised algorithms to solve this distributed constraint optimization problem. The first assumes that the route by which data is forwarded to the base station is fixed (either because the underlying communication network is a tree, or because an arbitrary choice of route has been made) and then calculates the optimal integration of actions that each node should perform. The second deals with flexible routing, and makes optimal decisions regarding both the sampling, transmitting, and forwarding actions that each node should perform, and also the route by which this data should be forwarded to the base station. The two algorithms represent a trade-off in optimality, communication cost, and processing time. In an empirical evaluation on sensor networks (whose underlying communication networks exhibit loops), we show that the algorithm with flexible routing delivers approximately twice the quantity of information to the base station compared to the algorithm with fixed routing. However, this gain comes at a considerable communication and computational cost (increasing both by a factor of 100 times). Thus, while the algorithm with flexible routing is suitable for networks with a small numbers of nodes, it scales poorly, and as the size of the network increases, the algorithm with fixed routing should be favoured.

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Cao, Hui. "Stabilization in wireless sensor networks." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1211079872.

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Zhao, Yao. "Autonomous Localization in 3D Surface Wireless Sensor Networks." Thesis, University of Louisiana at Lafayette, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3622968.

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Location awareness is imperative for a variety of sensing applications and network operations. Although a diversity of GPS-less and GPS-free solutions have been developed recently for autonomous localization in wireless sensor networks, they primarily target at 2D planar or 3D volumetric settings. There exists unique and fundamental hardness to extend them to 3D surfaces.

The contributions of this work are twofold. First, it proposes a theoretically-proven algorithm for the 3D surface localization problem. Seeing the challenges to localize general 3D surface networks and the solvability of the localization problem on single-value (SV) surface, this work proposes the cut-and-sew algorithm that takes a divide-and-conquer approach by partitioning a general 3D surface network into SV patches, which are localized individually and then merged into a unified coordinates system. The algorithm is optimized by discovering the minimum SV partition, an optimal partition that creates a minimum set of SV patches.

Second, it develops practically-viable solutions for real-world sensor network settings where the inputs are often noisy. The proposed algorithm is implemented and evaluated via simulations and experiments in an indoor testbed. The results demonstrate that the proposed cut-and-sew algorithm achieves perfect 100% localization rate and the desired robustness against measurement errors.

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Huang, Ying. "Progressive image mosaicking in wireless image sensor networks." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28439.

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Prevailing image mosaicking algorithms generate a complete image that incorporates a variety of different images. This variety is captured by different camera sensors. However, these traditional approaches cannot be directly applied to the emerging Wireless Image Sensor Networks (WISNs), because the slow image transmission over a wireless channel causes a noticeable delay before an entire image can be received by its receiver node in a WISN. In this thesis, we propose a Progressive Image Mosaicking Algorithm (PIMA) based on the multi-scan feature of Progressive JPEG (P-JPEG). PIMA's distinguishing characteristic is that it successfully performs mosaicking by using segmental data of images, as opposed to traditional methods, which require the complete data from all images. PIMA mosaics images that are decoded from P-JPEG scans at three levels of quality, and delivers an approximate view of the scene in a short time while the reception of further image data is in progress. Thereafter, it updates the image registration on two other refined levels to gradually enhance the display quality. We developed the concept of Richer Information and Likeliest (RIL) block pair, which is a variation of the Sum of Absolute Difference (SAD) and greatly improves the accuracy of image registration. Experimental results show that PIMA decreases the time delay before the first display of the scene, while preserving an equivalent performance of existing patch-based image mosaicking algorithms.

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Zhang, Yinuo, and 张一诺. "Evaluating continuous probabilistic queries over constantly-evolving data." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45589835.

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GhasemAghaei, Reza. "Routing in wireless sensor networks: An ant-inspired approach." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27687.

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The field of routing and sensor networking is an important and challenging research area of network computing today. Advancements in wireless sensor networks (WSNs) enable a wide range of environmental monitoring and object tracking applications. Routing in WSN is a challenging task. As the size of the network increases, routing becomes more complex. Therefore, biologically-inspired intelligent algorithms have been taken into consideration to address this problem. Ant routing algorithms have shown excellent performance when applied to WSN routing. This thesis presents routing algorithms in WSN, the current use of swarm intelligence for routing in WSN, explains different ant routing algorithms and shows why some existing ant routing algorithms do not work well for WSN. Consequently, we present four ant-colony based routing algorithms, which are suitable for WSN. Our proposed algorithms take into consideration the WSN requirements, including energy consumption, success rate, and time delay. In addition, one of our algorithms is a multimedia-enabled routing algorithm, which is suitable for single-source-to-single-destination multimedia data traffic to optimize different performance criteria, especially end-to-end delay and jitter. The last proposed algorithm is a many-to-one routing algorithm, which facilitates congestion avoidance in the network. The findings in this thesis are supported with several computer simulations.

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Yang, Fucheng. "Noncoherent fusion detection in wireless sensor networks." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/360402/.

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The main motivation of this thesis is to design low-complexity high efficiency noncoherent fusion rules for the parallel triple-layer wireless sensor networks (WSNs) based on frequency-hopping Mary frequency shift keying (FH/MFSK) techniques, which are hence referred to as the FH/MFSK WSNs. The FH/MFSKWSNs may be employed to monitor single or multiple source events (SEs)with each SE having multiple states. In the FH/MFSKWSNs, local decisions made by local sensor nodes (LSNs) are transmitted to a fusion center (FC) with the aid of FH/MFSK techniques. At the FC, various noncoherent fusion rules may be suggested for final detection (classification) of the SEs’ states. Specifically, in the context of the FH/MFSK WSNs monitoring single M-ary SE, three noncoherent fusion rules are considered for fusion detection, which include the benchmark equal gain combining (EGC), and the proposed erasure-supported EGC (ES-EGC) as well as the optimum posterior fusion rules. Our studies demonstrate that the ES-EGC fusion rule may significantly outperform the EGC fusion rule, in the cases when the LSNs’ detection is unreliable and when the channel signal-to-noise ratio (SNR) is relative high. For the FH/MFSKWSNs monitoring multiple SEs, six noncoherent fusion rules are investigated, which include the EGC, ES-EGC, EGC assisted N-order IIC (EGC-NIIC), ES-EGC assisted N-order IIC (ES-EGC-NIIC), EGC assisted r-order IIC (EGC-rIIC) and the ES-EGC assisted r-order IIC (ES-EGC-rIIC). The complexity, characteristics as well as detection performance of these fusion rules are investigated. Our studies show that the ES-EGC related fusion rules are highly efficient fusion rules, which have similar complexity as the corresponding EGC related fusion rules, but usually achieve better detection performance than the EGC related fusion rules. Although the ES-EGC is a single-user fusion rule, it is however capable of mitigating the multiple event interference (MEI) generated by multiple SEs. Furthermore, in some of the considered fusion rules, the embedded parameters may be optimized for the FH/MFSK WSNs to achieve the best detection performance. As soft-sensing is often more reliable than hard-sensing, in this thesis, the FH/MFSK WSNs with the LSNs using soft-sensing are investigated associated with the EGC and ES-EGC fusion rules. Our studies reveal that the ES-EGC becomes highly efficient, when the sensing at LSNs is not very reliable. Furthermore, as one of the applications, our FH/MFSK WSN is applied for cognitive spectrum sensing of a primary radio (PR) system constituted by the interleaved frequencydivision multiple access (IFDMA) scheme, which supports multiple uplink users. Associated with our cognitive spectrum sensing system, three types of energy detection based sensing schemes are addressed, and four synchronization scenarios are considered to embrace the synchronization between the received PR IFDMA signals and the sampling operations at cognitive spectrum sensing nodes (CRSNs). The performance of the FH/MFSK WSN assisted spectrum sensing system with EGC or ES-EGC fusion rule is investigated. Our studies show that the proposed spectrum sensing system constitutes one highly reliable spectrum sensing scheme, which is capable of exploiting the space diversity provided by CRSNs and the frequency diversity provided by the IFDMA systems. Finally, the thesis summarises our discoveries and provides discussion on the possible future research issues.

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Sinha, Saket. "Reliable and Efficient Routing for Wireless Sensor Networks." Thesis, California State University, Long Beach, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10263570.

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The latest advances in technology have facilitated the emergence of Wireless Sensor Networks (WSNs) as a promising technology. Because of their wide range of applications in industry, environmental monitoring, military and civilian domains, WSNs have become one of the most popular topics for research and development. The sensor nodes are low in cost and are simple in architecture. Wireless sensor networks are being employed in security-critical applications. However, their inherent characteristics make them prone to various security outbreaks that can negatively affect data collection. The current project presents an active detection-based routing scheme for WSNs, which can quickly create numerous detection routes as well as obtain nodal trust and thereby improve data security. Simulation results show that this scheme can detect Black Hole attacks, protect against them, and conserve energy, thus improving the network lifetime.

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Gong, P. "Energy efficient and secure wireless communications for wireless sensor networks." Thesis, City, University of London, 2017. http://openaccess.city.ac.uk/18026/.

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This dissertation considers wireless sensor networks (WSNs) operating in severe environments where energy efficiency and security are important factors. This main aim of this research is to improve routing protocols in WSNs to ensure efficient energy usage and protect against attacks (especially energy draining attacks) targeting WSNs. An enhancement of the existing AODV (Ad hoc On-Demand Distance Vector) routing protocol for energy efficiency, called AODV-Energy Harvesting Aware (AODVEHA), is proposed and evaluated. It not only inherits the advantages of AODV which are well suited to ad hoc networks, but also makes use of the energy harvesting capability of sensor nodes in the network. In addition to the investigation of energy efficiency, another routing protocol called Secure and Energy Aware Routing Protocol (ETARP) designed for energy efficiency and security of WSNs is presented. The key part of the ETARP is route selection based on utility theory, which is a novel approach to simultaneously factor energy efficiency and trustworthiness of routes in the routing protocol. Finally, this dissertation proposes a routing protocol to protect against a specific type of resource depletion attack called Vampire attacks. The proposed resource-conserving protection against energy draining (RCPED) protocol is independent of cryptographic methods, which brings advantage of less energy cost and hardware requirement. RCPED collaborates with existing routing protocols, detects abnormal sign of Vampire attacks and determines the possible attackers. Then routes are discovered and selected on the basis of maximum priority, where the priority that reflects the energy efficiency and safety level of route is calculated by means of Analytic Hierarchy Process (AHP). The proposed analytic model for the aforementioned routing solutions are verified by simulations. Simulations results validate the improvements of proposed routing approaches in terms of better energy efficiency and guarantee of security.

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Heo, Nojeong Varshney Pramod K. "Distributed deployment algorithms for mobile wireless sensor networks." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.

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Hull, Bret Warren 1980. "Techniques for mitigating congestion in wireless sensor networks." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/30170.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2005.
Includes bibliographical references (p. 99-105).
Network congestion occurs when offered traffic load exceeds available capacity at any point in a network. In wireless sensor networks, congestion causes overall channel quality to degrade and loss rates to rise, leads to buffer drops and increased delays (as in wired networks), and tends to be grossly unfair toward nodes whose data has to traverse a larger number of radio hops. Congestion control in wired networks is usually done using end-to-end and network-layer mechanisms acting in concert. However, this approach does not solve the problem in wireless networks because concurrent radio transmissions on different "links" interact with and affect each other, and because radio channel quality shows high variability over multiple time-scales. In this thesis, we examine three techniques that span different layers of the traditional protocol stack: hop-by-hop flow control, rate limiting source traffic when transit traffic is present, and a prioritized medium access control (MAC) protocol. We implement these techniques and present experimental results from a 55-node in-building wireless sensor network. We demonstrate that the combination of these techniques can improve network efficiency by a factor of three under realistic workloads.
by Bret Warren Hull.
S.M.

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Finchelstein, Daniel Frederic. "Low-power digital processor for wireless sensor networks." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34109.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.
Includes bibliographical references (p. 69-72).
In order to make sensor networks cost-effective and practical, the electronic components of a wireless sensor node need to run for months to years on the same battery. This thesis explores the design of a low-power digital processor for these sensor nodes, employing techniques such as hardwired algorithms, lowered supply voltages, clock gating and subsystem shutdown. Prototypes were built on both a FPGA and ASIC platform, in order to verify functionality and characterize power consumption. The resulting 0.18[micro]m silicon fabricated in National Semiconductor Corporation's process was operational for supply voltages ranging from 0.5V to 1.8V. At the lowest operating voltage of 0.5V and a frequency of 100KHz, the chip performs 8 full-accuracy FFT computations per second and draws 1.2nJ of total energy per cycle. Although this energy/cycle metric does not surpass existing low-energy processors demonstrated in literature or commercial products, several low-power techniques are suggested that could drastically improve the energy metrics of a future implementation.
by Daniel Frederic Finchelstein.
S.M.

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23

Kifayat, Kashif. "Group-based secure communication for wireless sensor networks." Thesis, Liverpool John Moores University, 2008. http://researchonline.ljmu.ac.uk/5899/.

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Wireless Sensor Networks (WSNs) are a newly developed networking technology consisting of multifunctional sensor nodes that are small in size and communicate over short distances. Continuous growth in the use of Wireless Sensor Networks (WSN) in sensitive applications such as military or hostile environments and also generally has resulted m a requirement for effective security mechanisms in the system design In order to protect the sensitive data and the sensor readings, shared keys should be used to encrypt the exchanged messages between communicating nodes. Many key management schemes have been developed recently and a serious threat highlighted in all of these schemes is that of node capture attacks, where an adversary gains full control over a sensor node through direct physical access. This can lead an adversary to compromise the communication of an entire WSN. Additionally ignoring security issues related to data aggregation can also bring large damage to WSNs. Furthermore, in case an aggregator node, group leader or cluster head node fails there should be a secure and efficient way of electing or selecting a new aggregator or group leader node in order to avoid adversary node to be selected as a new group leader. A key management protocol for mobile sensor nodes is needed to enable them to securely communicate and authenticate with the rest of the WSN.

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Mahjoub, Reem Khalid. "Efficient Actor Recovery Paradigm for Wireless Sensor and Actor Networks." Thesis, University of Bridgeport, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10745143.

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Wireless sensor networks (WSNs) are becoming widely used worldwide. Wireless Sensor and Actor Networks (WSANs) represent a special category of WSNs wherein actors and sensors collaborate to perform specific tasks. WSANs have become one of the most preeminent emerging type of WSNs. Sensors with nodes having limited power resources are responsible for sensing and transmitting events to actor nodes. Actors are high-performance nodes equipped with rich resources that have the ability to collect, process, transmit data and perform various actions. WSANs have a unique architecture that distinguishes them from WSNs. Due to the characteristics of WSANs, numerous challenges arise. Determining the importance of factors usually depends on the application requirements.

The actor nodes are the spine of WSANs that collaborate to perform the specific tasks in an unsubstantiated and uneven environment. Thus, there is a possibility of high failure rate in such unfriendly scenarios due to several factors such as power fatigue of devices, electronic circuit failure, software errors in nodes or physical impairment of the actor nodes and inter-actor connectivity problem. It is essential to keep inter-actor connectivity in order to insure network connectivity. Thus, it is extremely important to discover the failure of a cut-vertex actor and network-disjoint in order to improve the Quality-of-Service (QoS). For network recovery process from actor node failure, optimal re-localization and coordination techniques should take place.

In this work, we propose an efficient actor recovery (EAR) paradigm to guarantee the contention-free traffic-forwarding capacity. The EAR paradigm consists of Node Monitoring and Critical Node Detection (NMCND) algorithm that monitors the activities of the nodes to determine the critical node. In addition, it replaces the critical node with backup node prior to complete node-failure which helps balances the network performance. The packet is handled using Network Integration and Message Forwarding (NIMF) algorithm that determines the source of forwarding the packets (Either from actor or sensor). This decision-making capability of the algorithm controls the packet forwarding rate to maintain the network for longer time. Furthermore, for handling the proper routing strategy, Priority-Based Routing for Node Failure Avoidance (PRNFA) algorithm is deployed to decide the priority of the packets to be forwarded based on the significance of information available in the packet. To validate the effectiveness of the proposed EAR paradigm, we compare the performance of our proposed work with state-of the art localization algorithms. Our experimental results show superior performance in regards to network life, residual energy, reliability, sensor/ actor recovery time and data recovery.

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Fei, Xin. "Coverage-preserving and energy-conserving protocols for wireless sensor networks." Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27131.

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Keeping sensing coverage while saving energy of wireless sensor network is one of major challenges in wireless sensor network which includes three fundamental research aspects: coverage discover methods, conflict resolve algorithm and wakeup strategy. By means of computing geometry and computer graphics some solutions proposed for the wired sensor network were transplant to the wireless sensor network. However, the heavy message overhead and the centralized model made most of them can not gracefully handle the more restrict conditions in the wireless sensor network to resolve Coverage Problem. In this thesis, we propose efficient coverage-preserving and energy-conserving protocols for wireless sensor networks. We discuss our protocols and their implementation using ns-2 simulator. We also present an extensive set of simulation experiments to evaluate their performance using several scenarios.

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Du, Yan. "A Progressively Reliable Image Transport Protocol over Wireless Sensor Networks." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27975.

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Images are extensively used in Wireless Multimedia Sensor Networks (WMSN) for surveillance and object monitoring. The transmission of image data constitutes a significant portion of network bandwidth. Given the inherent differences of Wireless Sensor Networks (WSN) from wired networks, such as high probability of non-congestion related packet loss, very low bandwidth, Quality of Service (QoS) requirements, and limited processing power, the traditional transport protocol---the Transmission Control Protocol (TCP)---is not suitable for transferring images over WSN. In this thesis, a Progressively Reliable Image Transport Protocol---PITP, is proposed. First, with the support of progressive JPEG and out-of-order delivery of packets, this new protocol can display images smoothly with incremental quality. Second, this protocol guarantees receiver-controlled reliability and sound congestion control. In addition, a synchronization control mechanism is proposed within the protocol. A series of experiments are designed and simulated with ns2 to evaluate the performance of PITP. According to the results, PITP is proved to be suitable for image transmission over WSN.

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Tian, Di. "Node activity scheduling schemes in large-scale wireless sensor networks." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/29266.

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In wireless sensor networks that consist of a large number of low-power, short-lived, unreliable sensors, one of the main design challenges is to obtain long system lifetime without sacrificing sensing quality; i.e. sensing coverage in this context. In this thesis, we first propose a node-scheduling scheme, which can reduce system overall energy consumption, therefore increasing system lifetime, by identifying redundant nodes with respect to sensing coverage and then assigning them an off duty operation mode which has lower energy consumption than the normal on-duty mode. Our scheme aims at completely preserving original sensing coverage. Practically, sensing coverage degradation caused by location error, packet loss and node failure is very limited, not more than 1%, as shown by our experimental results. We implement the proposed scheme in NS-2, as an extension of the LEACH protocol and compare its energy consumption with the original LEACH. Simulation results exhibit noticeably longer system lifetime with our scheme as compared to earlier algorithm. The first scheme we propose aims at completely preserving sensing coverage. This, however, requires each node to get, in some way, the knowledge of its own and its neighbors' location information. Also, in that scheme, each node has to perform some calculations to determine whether to take an off-duty status. To alleviate these restrictions, we propose and study several alternative node-scheduling schemes, which cannot guarantee the complete preservation of the original system coverage, but are nonetheless more light-weighted and flexible than the previous one. The simulation results compare these schemes with the previous one and demonstrate their effectiveness. In a single wireless sensor network, sensors are performing two operations: sensing and communication. Therefore, there might exist two kinds of redundancy in the network. Most of the previous work addressed only one kind of redundancy: sensing or communication alone. Although there have been research efforts trying to combine consideration of coverage and connectivity maintenance in a single activity scheduling, their theoretical basis for safe scheduling integration condition is only applicable in those networks that are initially fully covered by sensors. Random node deployment often makes initial sensing holes inside the deployed area inevitable, even in an extremely high-density network. Therefore, in this thesis, we enhance these works to support general wireless sensor networks by proving another conclusion: "the communication range is twice the sensing range" is the sufficient condition and the tight lower bound to ensure that complete coverage preservation implies connectivity among active nodes, if the original network topology (consisting of all the deployed nodes) is connected. Also, we extend the results to k-degree network connectivity and k-degree coverage preservation.

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Asim, Muhammad. "Self-organization and management of wireless sensor networks." Thesis, Liverpool John Moores University, 2010. http://researchonline.ljmu.ac.uk/5998/.

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Wireless sensor networks (WSNs) are a newly deployed networking technology consisting of multifunctional sensor nodes that are small in size and communicate over short distances. These sensor nodes are mainly in large numbers and are densely deployed either inside the phenomenon or very close to it. They can be used for various application areas (e.g. health, military, home). WSNs provide several advantages over traditional networks, such as large-scale deployment, highresolution sensed data, and application adaptive mechanisms. However, due to their unique characteristics (having dynamic topology, ad-hoc and unattended deployment, huge amount of data generation and traffic flow, limited bandwidth and energy), WSNs pose considerable challenges for network management and make application development nontrivial. Management of wireless sensor networks is extremely important in order to keep the whole network and application work properly and continuously. Despite the importance of sensor network management, there is no generalize solution available for managing and controlling these resource constrained WSNs. In network management of WSNs, energy-efficient network selforganization is one of the main challenging issues. Self-organization is the property which the sensor nodes must have to organize themselves to form the network. Selforganization of WSNs is challenging because of the tight constraints on the bandwidth and energy resources available in these networks. A self organized sensor network can be clustered or grouped into an easily manageable network. However, existing clustering schemes offer various limitations. For example, existing clustering schemes consume too much energy in cluster formation and re-formation. This thesis presents a novel cellular self-organizing hierarchical architecture for wireless sensor networks. The cellular architecture extends the network life time by efficiently utilizing nodes energy and support the scalability of the system. We have analyzed the performance of the architecture analytically and by simulations. The results obtained from simulation have shown that our cellular architecture is more energy efficient and achieves better energy consumption distribution. The cellular architecture is then mapped into a management framework to support the network management system for resource constraints WSNs. The management framework is self-managing and robust to changes in the network. It is application-co-operative and optimizes itself to support the unique requirements of each application. The management framework consists of three core functional areas i.e., configuration management, fault management, and mobility management. For configuration management, we have developed a re-configuration algorithm to support sensor networks to energy-efficiently re-form the network topology due to network dynamics i.e. node dying, node power on and off, new node joining the network and cells merging. In the area of fault management we have developed a new fault management mechanism to detect failing nodes and recover the connectivity in WSNs. For mobility management, we have developed a two phase sensor relocation solution: redundant mobile sensors are first identified and then relocated to the target location to deal with coverage holes. All the three functional areas have been evaluated and compared against existing solutions. Evaluation results show a significant improvement in terms of re-configuration, failure detection and recovery, and sensors relocation.

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Ellul, Joshua. "Run-time compilation techniques for wireless sensor networks." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/346328/.

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Wireless sensor networks research in the past decade has seen substantial initiative,support and potential. The true adoption and deployment of such technology is highly dependent on the workforce available to implement such solutions. However, embedded systems programming for severely resource constrained devices, such as those used in typical wireless sensor networks (with tens of kilobytes of program space and around ten kilobytes of memory), is a daunting task which is usually left for experienced embedded developers. Recent initiative to support higher level programming abstractions for wireless sensor networks by utilizing a Java programming paradigm for resource constrained devices demonstrates the development benefits achieved. However, results have shown that an interpreter approach greatly suffers from execution overheads. Run-time compilation techniques are often used in traditional computing to make up for such execution overheads. However, the general consensus in the field is that run-time compilation techniques are either impractical, impossible, complex, or resource hungry for such resource limited devices. In this thesis, I propose techniques to enable run-time compilation for such severely resource constrained devices. More so, I show not only that run-time compilation is in fact both practical and possible by using simple techniques which do not require any more resources than that of interpreters, but also that run-time compilation substantially increases execution efficiency when compared to an interpreter.

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Kelkar, Harshvardhan. "Boundary Marking of Phenomenon using Wireless Sensor Networks." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1258666674.

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Wang, Ke. "Designing authenication scheme for wireless sensor networks." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B42841732.

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Entezami, Fariborz. "Link-quality based routing framework for wireless sensor networks." Thesis, Kingston University, 2015. http://eprints.kingston.ac.uk/37346/.

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Intelligence is the power which makes the owner capable of making a decision defined by reasoning. When traditional solutions and approaches, such as First Principal Modelling or Statistical Modelling, are not feasible or able to effectively address complex real- world problems, then Computational Intelligence with some nature-inspired computational techniques and methodologies is employed. For transferring data between two non-directly connected devices when some other devices are in-between, a set of rules are used by routers which are devices between sender and receiver, to determine the most appropriate paths into which routers should forward data toward the intended destination. This set of rules is called routing protocol. Researchers use some computational itelligence techniques to design network routing protocols. Wireless Sensor Networks (WSNs) play an important role in today's data communication systems and researchers are expected to proliferate in the field of wireless communication in the near future. The deployment of wireless sensor networks offer several advantages in comparison to traditional infrastructure-based networks, such as fully distributed mobile operation, the easy discovery of joining wireless devices, and instant and low cost network setup. Designing an effective routing protocol is one of the main challenges in the ad-hoc networking paradigm and the utilisation of an adequate link-cost metric is essential. WSN researchers address issues such as low throughput and high latency in wireless sensor data communication. Routing Protocols in WSNs play a key role in data communication and the main parameter in all routing protocols is data communications link-cost. This research delivers two surveys on existing routing protocols and link-quality metrocs for wireless sensor networks. Most of the routing protocols in this area are considered in different groups. The majority of link-quality metrics in WSNs are studied in different categories. Link-quality and traffic-aware metrics account for most of the metrics, as well as metrics in multi-channel networks and cognitive radio systems, which are also considered in detail. Metrics are reviewed in detail in terms of their performance; summary and comparison tables of link-quality metrics are provided to enable better comparison and show a brief overview of their appearance to get a clearer picture. Routing-metrics are important is determining paths and maintaining quality of service in routing protocols. The most efficient metrics need to send packets to maintain link-quality measurement by using the Radi Frequency (RF) module. In this study, a set of statistical analyses is done on some link-quality metrics to select the best metric for energy-aware scenarios. Two prominent link-quality metrics; Received Signal Strength Indication (RSSI) and Link-Quality Indication (LQI), are described in detail. The symmetry of RSSI and LQI in two directions is studied, and relations with the Expected Transmission Count (ETX), RSSI, and LQI as link-quality metrics are analysed. The evaluation in this research is based on a series of WSN test-beds in real scenarios. Due to implementation of routing protocols in limited power supply devices in WSNs, one novel link-quality metric and also some routing protocols for wireless sensor networks are proposed in this research to obtain better performance in different scenarios. Rainbow Collection Tree Protocol (RCTP) is presented and evaluated as an enhanced version of Collection Tree Protocol (CTP). It uses the Trickle algorithm to optimise overhead cost and the algorithm also makes RCTP quickly adaptable to changes in topology. The Rainbow mechanism is used in RCTP to detect and route around connectivity nodes and avoid routes through dead-end paths. Energy-efficient Rainbow Collection Tree Routing Protocol (ERCRP) is presented and evaluated as a novel, real-time, position-based and energy-efficient routing protocol in this research. ERCRP is a lightweight protocol that reduced the number of nodes which receive the RF signal using a novel Parent Forwarding Region (PFR) algorithm. ERCRP as a Geographical Routing Protocol (GRP) reduced the number of forwarding nodes and thus decreases traffic and packet collision in the network. WSNs are used in three-dimension (3D) scenarios such as sea or land surfaces with different levels of height. Three-Dimension Position-Based Adaptive Real-Time Routing Protocol (3DPBARP) is presented and evaluated as a novel, real-time, position-based and energy-efficient routing protocol for WSNs in this research. 3DPBARP is a lightweight protocol that reduces the number of nodes which received the RF signal using a novel PFR algorithm. 3DPBARP as a GRP decreases the number of nodes which participate in packet forwarding and thus shrink the traffic and collision in the network.

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Yang, Yang. "Geometry in Wireless Sensor Networks In-network Information Processing and Localization." Thesis, University of Louisiana at Lafayette, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3622965.

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In this dissertation, firstly, we propose a geographic location free double-ruling based approach for general 3D sensor networks with possibly complicated topology and geometric shapes. Without the knowledge of the geographic location and the distance bound, a query simply travels along a simple curve with the guaranteed success to retrieve aggregated data through time and space with one or different types across the network. Extensive simulations and comparisons show the proposed scheme with low cost and a balanced traffic load.

Secondly, we explore 3D surface network localization with terrain model. A digital terrain model (DTM), available to public with a variable resolution up to one meter, is a 3D representation of a terrain's surface. It is commonly built using remote sensing technology or from land surveying and can be easily converted to a triangular mesh. Given a sensor network deployed on the surface of a 3D terrain with one-hop distance information available, we can extract a triangular mesh from the connectivity graph of the network. The constraint that the sensors must be on the known 3D terrain's surface ensures that the triangular meshes of the network and the DTM of the terrain's surface approximate the same geometric shape and overlap. We propose a fully distributed algorithm to construct a well-aligned mapping between the two triangular meshes. Based on this mapping, each sensor node of the network can easily locate reference grid points from the DTM to calculate its own geographic location. We carry out extensive simulations under various scenarios to evaluate the overall performance of the proposed localization algorithm. We also discuss the possibility of 3D surface network localization with mere connectivity and the results are promising.

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Scholtz, Andre. "An agent based layered framework to facilitate intelligent Wireless Sensor Networks." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/12677.

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Includes bibliographical references (leaves 78-80).
Wireless Sensor Networks (WSNs) are networks of small, typically low-cost hardware devices which are able to sense various physical phenomenon in their surrounding environments. These simple nodes are also able to perform basic processing and wirelessly communicate with each other. The power of these networks arise from their ability to combine their many vantage points of the individual nodes and to work together. This allows for behaviour to emerge which is greater than the sum of the ability of all the nodes in the network. The complexity of these networks varies based on the application domain and the physical phenomenon being sensed. Although sensor networks are currently well understood and used in a number of real world applications, a number limitations still exit. This research aims to overcome a number of issues faced by current WSNs, the largest of which is their monolithic or tightly coupled structure which result in static and application specific WSNs. We aim to overcome these issues by designing a dynamically reconfigurable system which is application neutral. The proposed system is also required to facilitate intelligence and be sufficiently efficient for low power sensor node hardware.

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Chellappan, Sriram. "On deployment and security in mobile wireless sensor networks." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1195662143.

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Bouhafs, Faycal. "Semantic clustering mechanisms for communication in wireless sensor networks." Thesis, Liverpool John Moores University, 2007. http://researchonline.ljmu.ac.uk/5809/.

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Gwilliams, Christopher. "Using local and global knowledge in wireless sensor networks." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/73423/.

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Wireless sensor networks (WSNs) have advanced rapidly in recent years and the volume of raw data received at an endpoint can be huge. We believe that the use of local knowledge, acquired from sources such as the surrounding environment, users and previously sensed data, can improve the efficiency of a WSN and automate the classification of sensed data. We define local knowledge as knowledge about an area that has been gained through experience or experimentation. With this in mind, we have developed a three-tiered architecture for WSNs that uses differing knowledge-processing capabilities at each tier, called the Knowledge-based Hierarchical Architecture for Sensing (KHAS). A novel aligning ontology has been created to support K-HAS, joining widely used, domain-specific ontologies from the sensing and observation domains. We have shown that, as knowledge-processing capabilities are pushed further out into the network, the profit - defined as the value of sensed data - is increased; where the profit is defined as the value of the sensed data received by the end user. Collaborating with Cardiff University School of Biosciences, we have deployed a variation of K-HAS in the Malaysian rainforest to capture images of endangered wildlife, as well as to automate the collection and classification of these images. Technological limitations prevented a complete implementation of K-HAS and an amalgamation of tiers was made to create the Local knowledge Ontology-based Remote-sensing Informatics System (LORIS). A two week deployment in Malaysia suggested that the architecture was viable and that, even using local knowledge at the endpoint of a WSN, improved the efficiency of the network. A simulation was implemented to model K-HAS and this indicated that the network became more efficient as knowledge was pushed further out towards the edge, by allowing nodes to prioritise sensed data based on inferences about its content.

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Kumar, Santosh. "Foundations of coverage for wireless sensor networks." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1154986262.

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Wang, Ke, and 黃岢. "Designing authenication scheme for wireless sensor networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B42841732.

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Demirbas, Murat. "Scalable design of fault-tolerance for wireless sensor networks." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1091466471.

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Thesis (Ph. D.)--Ohio State University, 2004.
Title from first page of PDF file. Document formatted into pages; contains xii, 150 p.; also includes graphics Includes bibliographical references (p. 142-150). Available online via OhioLINK's ETD Center

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Dai, Rui. "Correlation-based communication in wireless multimedia sensor networks." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42736.

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Wireless multimedia sensor networks (WMSNs) are networks of interconnected devices that allow retrieving video and audio streams, still images, and scalar data from the environment. In a densely deployed WMSN, there exists correlation among the observations of camera sensors with overlapped coverage areas, which introduces substantial data redundancy in the network. In this dissertation, efficient communication schemes are designed for WMSNs by leveraging the correlation of visual information observed by camera sensors. First, a spatial correlation model is developed to estimate the correlation of visual information and the joint entropy of multiple correlated camera sensors. The compression performance of correlated visual information is then studied. An entropy-based divergence measure is proposed to predict the compression efficiency of performing joint coding on the images from correlated cameras. Based on the predicted compression efficiency, a clustered coding technique is proposed that maximizes the overall compression gain of the visual information gathered in WMSNs. The correlation of visual information is then utilized to design a network scheduling scheme to maximize the lifetime of WMSNs. Furthermore, as many WMSN applications require QoS support, a correlation-aware QoS routing algorithm is introduced that can efficiently deliver visual information under QoS constraints. Evaluation results show that, by utilizing the correlation of visual information in the communication process, the energy efficiency and networking performance of WMSNs could be improved significantly.

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Eames, Adam McLendon. "Enabling path planning and threat avoidance with wireless sensor networks." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33277.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.
Includes bibliographical references (p. 67-68).
Wireless sensor networks can provide real time navigation instructions to robots or people attempting to travel in hazardous environments. This thesis presents the design, analysis, and implementation of a distributed system providing path planning and threat avoidance capability to mobile users. Contributions of the system include a unique framework for modeling for the effects of threats as well as original algorithms for discovering the safest path between any two points in the network. The prototype implementation was built using the Cricket v2 / TinyOS platform, and the results from tests of the implementation are presented.
by Adam McLendon Eames.
M.Eng.

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Taylor, Christopher J. (Christopher Jorgen). "Simultaneous localization and tracking in wireless ad-hoc sensor networks." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33375.

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Thesis (M. Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.
Includes bibliographical references (p. 77-79).
In this thesis we present LaSLAT, a sensor network algorithm that uses range measurements between sensors and a moving target to simultaneously localize the sensors, calibrate sensing hardware, and recover the target's trajectory. LaSLAT is based on a Bayesian filter that updates a probability distribution over the parameters of interest as measurements arrive. The algorithm is distributable and requires a fixed amount of storage space with respect to the number of measurements it has incorporated. LaSLAT is easy to adapt to new types of hardware and new physical environments due to its use of intuitive probability distributions: one adaptation demonstrated in this thesis uses a mixture measurement model to detect and compensate for bad acoustic range measurements due to echoes. We present results from a centralized implementation of LaSLAT using a network of Cricket sensors. In both 2D and 3D networks, LaSLAT is able to localize sensors to within several centimeters of their ground truth positions while recovering a range measurement bias for each sensor and the complete trajectory of the mobile.
by Christopher J. Taylor.
M.Eng.and S.B.

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Bapat, Sandip Shriram. "On reliable and scalable management of wireless sensor networks." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1164809365.

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Yilmaz, Mine. "Duty Cycle Control In Wireless Sensor Networks." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608856/index.pdf.

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Recent advances in wireless communication and micro-electro-mechanical systems (MEMS) have led to the development of implementation of low-cost, low power, multifunctional sensor nodes. These sensor node are small in size and communicate untethered in short distances. The nodes in sensor networks have limited battery power and it is not feasible or possible to recharge or replace the batteries, therefore power consumption should be minimized so that overall network lifetime will be increased. In order to minimize power consumed during idle listening, some nodes, which can be considered redundant, can be put to sleep. In this thesis study, basic routing algorithms and duty cycle control algorithms for WSNs in the literature are studied. One of the duty cycle control algorithms, Role Alternating, Coverage Preserving, and Coordinated Sleep algorithm (RACP) is examined and simulated using the ns2 simulation environment. A novel duty cycle control algorithm, Sink Initiated Path Formation (SIPF) is proposed and compared to RACP in terms of sleep sensor ratio and time averaged coverage.

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46

Felemban, Emad. "Protocols for Mission-Critical Wireless Sensor Networks." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250184419.

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47

Wang, Demin. "Wireless Sensor Networks: Deployment Alternatives and Analytical Modeling." Cincinnati, Ohio : University of Cincinnati, 2008. http://rave.ohiolink.edu/etdc/view.cgi?acc_num=ucin1227036446.

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Thesis (Ph.D.)--University of Cincinnati, 2008.
Advisor: Dharma Agrawal Title from electronic thesis title page (viewed Feb.16, 2009). Keywords: Wireless Sensor Network; nonuniform deployment; lifetime. Includes abstract. Includes bibliographical references.

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Chang, Shih-Hao. "High performance communication framework for mobile sinks wireless sensor networks." Thesis, Liverpool John Moores University, 2009. http://researchonline.ljmu.ac.uk/5934/.

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A wireless sensor networks typically consist of thousand of nodes and each node has limited power, processing and bandwidth resources. Harvesting advances in the past decade in microelectronics, sensing, wireless communications and networking, sensor networks technology is expected to have a significant impact on our lives in the twenty-first century. Proposed applications of sensor networks include environmental monitoring, natural disaster prediction and relief, homeland security, healthcare, manufacturing, transportation, and home appliances and entertainment. However, Communication is one of the major challenges in wireless sensor networks as it is the main source for energy depletion. Improved network lifetime is a fundamental challenge of wireless sensor networks. Many researchers have proposed using mobile sinks as one possible solution to improve the lifetime of wireless sensor networks. The reason is that the typical manyto- one communication traffic pattern in wireless sensor networks imposes a heavy forwarding load on the nodes close to the sinks. However, it also introduces many research challenges such as the high communication overhead for updating the dynamic routing paths to connect to mobile sinks and packet loss problems while transmitted messages to mobile sinks. Therefore, our goal is to design a robust and efficient routing framework for both non-geographic aware and geographic aware mobile sinks wireless sensor networks. In order to achieve this goal in non-geographic based mobile sinks wireless sensor networks, we proposed a spider-net zone routing protocol to improve network efficiency and lifetime. Our proposed routing protocol utilise spider web topology inspired by the way spiders hunt prey in their web to provide reliable and high performance data delivery to mobile sinks. For routing in geographic aware based mobile sinks wireless sensor networks, we proposed a fault-tolerant magnetic coordinate routing algorithm to allow these network sensors to take advantage of geographic knowledge to build a routing protocol. Our proposed routing algorithm incorporates a coordinated routing algorithm for grid based network topology to improve network performance. Our third contribution is a component level fault diagnosis scheme for wireless sensor networks. The advantage of this scheme, causal model fault diagnosis, is that it can "deeply understand" and express the relationship among failure behaviours and node system components through causal relations. The above contributions constitute a novel routing framework to address the routing challenges in mobile sinks wireless sensor networks, Our framework considers both geographic and non-geographic aware based sensor networks to achieve energy efficient, high performance and network reliability. We have analyzed the proposed protocols and schemes and evaluated their performances using analytical study and simulations. The evaluation was based on the most important metries in wireless sensor networks, such as: power consumption and average delay. The evaluation shows that our solution is more energy efficient, improves the network performance, and provides data reliability in mobile sinks wireless sensor networks.

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Padhy, Paritosh. "Autonomous energy efficient protocols and strategies for wireless sensor networks." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/66390/.

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The aim of this research is to develop a model of a sensor network that will endeavour to monitor a hostile environment (one where communication within the network is difficult and the network entities are under risk due to physical damage). In this context, the study identifies the following key characteristics. A wireless sensor network (WSN) is a wireless network consisting of spatially distributed devices using sensors to monitor physical or environmental conditions at different locations. In addition to one or more sensors, each node in a WSN is typically equipped with a radio transceiver or other wireless communications device, a small micro controller, and an energy source, usually a battery. The size constraints on sensor nodes result in corresponding constraints on resources such as energy, memory, computational speed and bandwidth. Of these, energy is the most important since it is required for everything else. Thus, it directly influences the life-span of the nodes, hence, that of the system as a whole. Furthermore, the environment itself, where these sensor nodes are deployed, plays a big role in influencing the entire architecture of the network hardware platform and protocols that govern its smooth functioning. As a result the protocols required for governing the actions of the sensor nodes need to be designed accordingly. Against this background, this research facilitates the developent of an environmental sensor network called GlacsWeb (deployed inside a glacier in Norway) which focuses on providing useful information about sub-glacial dynamics. GlacsWeb nodes are deployed under very hostile conditions. The strain from the moving ice may damage the nodes and the en-glacial water bodies may carry the nodes far out of transmission range from a centrally located base station. For these reasons GlacsWeb nodes have a high rate of failure. In order to effectively tackle this problem, this research develops GW-MAC (a Medium Access Control protocol) which focuses on efficiently connecting GlacsWeb nodes in an ad-hoc manner. Moreover, the poorly understood nature of the glacier imposes further challenges in the area of sensing. Sub-glacial behaviour appears vary across the entire large mass of ice. For this reason, there is a strong need for nodes to make autonomous decisions to adapt their observation patterns and communication patterns accordingly to ensure maximum data is gathered with minimum consumption in energy. The study, therefore, develops USAC (A Utility Based Sensing and Communication Model for an Agent-Based Sensor Network), that provides a measure of utility by combining the task of both sensing and communication by the sensor nodes. The model, at first, develops a sensing protocol in which each agent node locally adjusts its sensing rate based on the value (importance) of the data it believes it will observe. Then, it details a communication protocol that finds optimal routes for relaying this data back the network base station based on the cost of communicating (derived from the opportunity cost of using the battery power for relaying data) it. Both GW-MAC and USAC have been tested in simulation and have shown to perform better than other similar models.

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Merrett, Geoff V. "Energy- and information-managed wireless sensor networks : modelling and simulation." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/65002/.

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Wireless Sensor Networks (WSNs) allow the remote and distributed monitoring of parameters in their deployed environment. WSNs are receiving increasing research interest, due to their ability to enable a wide range of applications, and their potential to have a major impact on ubiquitous computing. Many research challenges are encountered in retaining a useful network lifetime under constrains imposed by the limited energy reserves that are inherent in the small, locally-powered sensor nodes. This research addresses some of these challenges through the development and evaluation of energy- and information-managed algorithms leading to increased network lifetime. The first contribution of this research is the development of an Information manageD Energy-aware ALgorithm for Sensor networks with Rule Managed Reporting (IDEALS/RMR). IDEALS/RMR is an application-independent, localised system to control and manage the degradation of a network through the positive discrimination of packets. This is achieved by the novel combination of energy management (through IDEALS) and information management (through RMR) which increases the network lifetime at the possible expense of often trivial data. IDEALS/RMR is particularly suited to applications where sensor nodes are small, energy constrained, embedded devices particularly those that feature energy harvesting) that are required to report data in an unassisted fashion. The second contribution of this research is the analysis of various environmental and physical aspects of WSNs, and the effect that they have on the operation of nodes and networks. These aspects include energy components (stores, sources and consumers), sensing devices, wireless communication, and timing; these aspects are independently modelled and, through simulation, their effect on the operation of the network is quantified. The third contribution of this research is the evaluation of IDEALS/RMR using a simulator that has been specifically developed to integrate both the proposed environmental and physical models, and a novel node architecture that facilitates structured software design. A scenario depicting the use of a WSN to monitor pump temperature in a water pumping station is simulated, and highlights the benefits of the developed algorithms.

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Dissertations / Theses on the topic 'Querying (Computer science). Wireless sensor networks'

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