Robust Clock Synchronization In Wireless Sensor Networks
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Robust Clock Synchronization In Wireless Sensor Networks
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Author : Sawin Saibua
language : en
Publisher:
Release Date : 2010
Robust Clock Synchronization In Wireless Sensor Networks written by Sawin Saibua and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
Clock synchronization between any two nodes in a Wireless Sensor Network (WSNs) is generally accomplished through exchanging messages and adjusting clock offset and skew parameters of each node's clock. To cope with unknown network message delays, the clock offset and skew estimation schemes have to be reliable and robust in order to attain long-term synchronization and save energy. A joint clock offset and skew estimation scheme is studied and developed based on the Gaussian Mixture Kalman Particle Filter (GMKPF). The proposed estimation scheme is shown to be a more flexible alternative than the Gaussian Maximum Likelihood Estimator (GMLE) and the Exponential Maximum Likelihood Estimator (EMLE), and to be a robust estimation scheme in the presence of non-Gaussian/nonexponential random delays. This study also includes a sub optimal method called Maximum Likelihood-like Estimator (MLLE) for Gaussian and exponential delays. The computer simulations illustrate that the scheme based on GMKPF yields better results in terms of Mean Square Error (MSE) relative to GMLE, EMLE, GMLLE, and EMLLE, when the network delays are modeled as non-Gaussian/non-exponential distributions or as a mixture of several distributions.
Robust Clock Synchronization Methods For Wireless Sensor Networks
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Author : Jae Han Lee
language : en
Publisher:
Release Date : 2011
Robust Clock Synchronization Methods For Wireless Sensor Networks written by Jae Han Lee and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Wireless sensor networks (WSNs) have received huge attention during the recent years due to their applications in a large number of areas such as environmental monitoring, health and traffic monitoring, surveillance and tracking, and monitoring and control of factories and home appliances. Also, the rapid developments in the micro electro-mechanical systems (MEMS) technology and circuit design lead to a faster spread and adoption of WSNs. Wireless sensor networks consist of a number of nodes featured in general with energy-limited sensors capable of collecting, processing and transmitting information across short distances. Clock synchronization plays an important role in designing, implementing, and operating wireless sensor networks, and it is essential in ensuring a meaningful information processing order for the data collected by the nodes. Because the timing message exchanges between different nodes are affected by unknown possibly time-varying network delay distributions, the estimation of clock offset parameters represents a challenge. This dissertation presents several robust estimation approaches of the clock offset parameters necessary for time synchronization of WSNs via the two-way message exchange mechanism. In this dissertation the main emphasis will be put on building clock phase offset estimators robust with respect to the unknown network delay distributions. Under the assumption that the delay characteristics of the uplink and the downlink are asymmetric, the clock offset estimation method using the bootstrap bias correction approach is derived. Also, the clock offset estimator using the robust Mestimation technique is presented assuming that one underlying delay distribution is mixed with another delay distribution. Next, although computationally complex, several novel, efficient, and robust estimators of clock offset based on the particle filtering technique are proposed to cope with the Gaussian or non-Gaussian delay characteristics of the underlying networks. One is the Gaussian mixture Kalman particle filter (GMKPF) method. Another is the composite particle filter (CPF) approach viewed as a composition between the Gaussian sum particle filter and the KF. Additionally, the CPF using bootstrap sampling is also presented. Finally, the iterative Gaussian mixture Kalman particle filter (IGMKPF) scheme, combining the GMKPF with a procedure for noise density estimation via an iterative mechanism, is proposed.
Secure Localization And Time Synchronization For Wireless Sensor And Ad Hoc Networks
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Author : Radha Poovendran
language : en
Publisher: Springer Science & Business Media
Release Date : 2007-12-03
Secure Localization And Time Synchronization For Wireless Sensor And Ad Hoc Networks written by Radha Poovendran and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007-12-03 with Technology & Engineering categories.
This book presents the latest research results in the area of secure localization for both wireless mobile ad hoc networks and wireless sensor networks. It is suitable as a text for computer science courses in wireless systems and security. It includes implementation studies with mica2 mote sensors. Due to the open spectrum nature of wireless communication, it is subject to attacks and intrusions. Hence the wireless network synchronization needs to be both robust and secure. Furthermore, issues such as energy constraints and mobility make the localization process even more challenging. The book will also interest developers of secure wireless systems.
Secure Localization And Time Synchronization For Wireless Sensor And Ad Hoc Networks
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Author : Radha Poovendran
language : en
Publisher: Springer
Release Date : 2006-11-14
Secure Localization And Time Synchronization For Wireless Sensor And Ad Hoc Networks written by Radha Poovendran and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006-11-14 with Technology & Engineering categories.
This book presents the latest research results in the area of secure localization for both wireless mobile ad hoc networks and wireless sensor networks. It is suitable as a text for computer science courses in wireless systems and security. It includes implementation studies with mica2 mote sensors. Due to the open spectrum nature of wireless communication, it is subject to attacks and intrusions. Hence the wireless network synchronization needs to be both robust and secure. Furthermore, issues such as energy constraints and mobility make the localization process even more challenging. The book will also interest developers of secure wireless systems.
Synchronization In Wireless Sensor Networks
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Author : Erchin Serpedin
language : en
Publisher: Cambridge University Press
Release Date : 2009-07-30
Synchronization In Wireless Sensor Networks written by Erchin Serpedin and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009-07-30 with Computers categories.
Presents the key clock synchronization protocols, emphasizing design and optimization techniques for building efficient estimation schemes and performance benchmarks.
Distributed Clock Synchronization For Wireless Sensor Networks
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Author : Bin Luo
language : en
Publisher: Open Dissertation Press
Release Date : 2017-01-26
Distributed Clock Synchronization For Wireless Sensor Networks written by Bin Luo and has been published by Open Dissertation Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-01-26 with categories.
This dissertation, "Distributed Clock Synchronization for Wireless Sensor Networks" by Bin, Luo, 羅斌, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Clock synchronization for Wireless Sensor Networks (WSNs) has attracted lots of attention due to its importance for operations in WSNs. In traditional centralized clock synchronization algorithms, all the local information should be transmitted to a fusion center for processing, and the results need to be forwarded back to each individual sensor, thus resulting in a heavy burden on communication and computation in the network. In addition, it also lacks of adaptability to link failures and dynamic changes in the network topology, which greatly prevents their use in WSNs. Hence, in this thesis, we focus on developing energy-efficient distributed clock synchronization algorithms for WSNs. Firstly, global clock synchronization problem is investigated with time-varying clock parameters (skew and offset) owing to imperfect oscillator circuits. A distributed Kalman filter is developed for clock parameters tracking. The proposed algorithm only requires each node to exchange limited information with its direct neighbors, thus is energy efficient, scalable with network size, and is robust against changes in network connectivity. A low-complexity distributed algorithm based on Coordinate-Descent with Bootstrap (CD-BS) is also proposed to provide rapid initialization of the tracking algorithm. Simulation results show that the proposed distributed tracking algorithm achieves the long-term accuracy for the clock parameters close to the Bayesian Cramer-Rao Lower Bound. Secondly, the problem of global clock synchronization for WSNs in the presence of unknown exponential delays is studied. The joint maximum likelihood estimator of clock offsets, clock skews and fixed delays of the network is first formulated as a global linear programming (LP) problem. Based on the Alternating Direction Method of Multipliers (ADMM), we propose a fully-distributed synchronization algorithm that has low communication overhead and computation cost. Simulation results show that the proposed algorithm achieves better accuracy than consensus algorithm and the distributed least squares algorithm, and can always converge to the centralized optimal solution. Finally, global clock synchronization for WSNs under the exponentially distributed delays is re-visited with the fast convergence min-sum algorithm. The synchronization problem is cast into an optimization problem represented by factor graph, and a closed-form expression of the messages passed between nodes are derived. Simulation results show that this distributed algorithm can approach the centralized LP solution with faster convergence speed compared to ADMM-based algorithm. DOI: 10.5353/th_b5204913 Subjects: Sensor networks Synchronization Wireless communication systems
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Author :
language : en
Publisher:
Release Date : 1940
written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1940 with categories.
Clock Synchronization And Localization For Wireless Sensor Network
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Author : Cheng-Yu Han
language : en
Publisher:
Release Date : 2018
Clock Synchronization And Localization For Wireless Sensor Network written by Cheng-Yu Han and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
Wireless sensor networks (WSNs) play an important role in applications such as environmental monitoring, source tracking, and health care,... In WSN, sensors have the ability to perform data sampling, distributed computing and information fusion. To perform such complex tasks, clock synchronization and localization are two fundamental and essential algorithms. WSNs have been widely studied in the past years, and the scientific literature reports many outcomes that make them applicable for some applications. For some others, research still needs to find solutions to some of the challenges posed by battery limitation, dynamicity, and low computing clock rate. With the aim of contributing to the research on WSN, this thesis proposes new algorithms for both clock synchronization and localization. For clock synchronization, sensors converge their local physical clock to perform data fusion. By applying the clock synchronization algorithm, sensors converge the time difference and therefore work at the same rate. In view of dynamicity, low computing and sparsity of WSN, a new pulse-coupled decentralized synchronization algorithm is proposed to improve the precision of the synchronization. The benefit of this kind of algorithm is that sensors only exchange zero-bit pulse instead of packets, so not only the communication is efficient but also robust to any failure of the sensors in the network. Localization of sensors has been widely studied. However, the quality and the accuracy of the localization still have a large room to improve. This thesis apply Leave-out Sign-dominant Correlated Regions (LSCR) algorithm to localization problem. With LSCR, one evaluates the accurate estimates of confidence regions with prescribed confidence levels, which provide not only the location but also the confidence of the estimation. In this thesis, several localization approaches are implemented and compared. The simulation result shows under mild assumptions, LSCR obtains competitive results compared to other methods.
Time Synchronization And System Support For Energy Efficient Wireless Sensor Networks
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Author : Oldrine George Lewis
language : en
Publisher:
Release Date : 2007
Time Synchronization And System Support For Energy Efficient Wireless Sensor Networks written by Oldrine George Lewis and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Sensor networks categories.
"This thesis presents a design of a Wireless Sensor Network (WSN) and the implementation of an original time synchronization algorithm. The complete system support for energy efficient WSNs was developed. The new time synchronization algorithm called Sliding Clock Synchronization employs a simple, yet very effective algorithm to compensate for static and dynamic drifts in the frequencies of crystal oscillators used in the WSN nodes. As power is a very scarce and critical resource in most WSN s, a tight synchronization algorithm can reduce power consumption thereby increasing the life of a WSN. An accurate and reliable synchronization algorithm also enables the WSN to be used for applications that require a tight synchronization for data correlation. A hardware and software interface for an embedded web server has been provided so that the WSN can be monitored and controlled over the Internet. An interface for a GPS module enables the network to incorporate GPS time stamps in recording network events. A sensor node emulator has been developed so that a single node can emulate multiple nodes without additional hardware, thus providing a simple and cost, effective means to test the network performance with large number of nodes"--Leaf iii.
New Advances In Clock Synchronization For Wireless Sensor Networks
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Author : Mei Leng
language : en
Publisher: Open Dissertation Press
Release Date : 2017-01-26
New Advances In Clock Synchronization For Wireless Sensor Networks written by Mei Leng and has been published by Open Dissertation Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-01-26 with categories.
This dissertation, "New Advances in Clock Synchronization for Wireless Sensor Networks" by Mei, Leng, 冷梅, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. DOI: 10.5353/th_b4588045 Subjects: Synchronization Wireless sensor networks