Dissertations / Theses on the topic 'Wireless data networks'
To see the other types of publications on this topic, follow the link: Wireless data networks.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Wireless data networks.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Cui, Jin. "Data aggregation in wireless sensor networks." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI065/document.
Full textAbstract:
Depuis plusieurs années, l’agrégation de données sont considérés comme un domaine émergent et prometteur tant dans le milieu universitaire que dans l’industrie. L’énergie et la capacité du réseau seront donc économisées car il y aura moins de transmissions de données. Le travail de cette thèse s’intéresse principalement aux fonctions d’agrégation Nous faisons quatre contributions principales. Tout d’abord, nous proposons deux nouvelles métriques pour évaluer les performances des fonctions d’agrégations vue au niveau réseau : le taux d’agrégation et le facteur d’accroissement de la taille des paquets. Le taux d’agrégation est utilisé pour mesurer le gain de paquets non transmis grâce à l’agrégation tandis que le facteur d’accroissement de la taille des paquets permet d’évaluer la variation de la taille des paquets en fonction des politiques d’agrégation. Ces métriques permettent de quantifier l’apport de l’agrégation dans l’économie d’énergie et de la capacité utilisée en fonction du protocole de routage considéré et de la couche MAC retenue. Deuxièmement, pour réduire l’impact des données brutes collectées par les capteurs, nous proposons une méthode d’agrégation de données indépendante de la mesure physique et basée sur les tendances d’évolution des données. Nous montrons que cette méthode permet de faire une agrégation spatiale efficace tout en améliorant la fidélité des données agrégées. En troisième lieu, et parce que dans la plupart des travaux de la littérature, une hypothèse sur le comportement de l’application et/ou la topologie du réseau est toujours sous-entendue, nous proposons une nouvelle fonction d’agrégation agnostique de l’application et des données devant être collectées. Cette fonction est capable de s’adapter aux données mesurées et à leurs évolutions dynamiques. Enfin, nous nous intéressons aux outils pour proposer une classification des fonctions d’agrégation. Autrement dit, considérant une application donnée et une précision cible, comment choisir les meilleures fonctions d’agrégations en termes de performances. Les métriques, que nous avons proposé, sont utilisées pour mesurer la performance de la fonction, et un processus de décision markovien est utilisé pour les mesurer. Comment caractériser un ensemble de données est également discuté. Une classification est proposée dans un cadre précisWireless Sensor Networks (WSNs) have been regarded as an emerging and promising field in both academia and industry. Currently, such networks are deployed due to their unique properties, such as self-organization and ease of deployment. However, there are still some technical challenges needed to be addressed, such as energy and network capacity constraints. Data aggregation, as a fundamental solution, processes information at sensor level as a useful digest, and only transmits the digest to the sink. The energy and capacity consumptions are reduced due to less data packets transmission. As a key category of data aggregation, aggregation function, solving how to aggregate information at sensor level, is investigated in this thesis. We make four main contributions: firstly, we propose two new networking-oriented metrics to evaluate the performance of aggregation function: aggregation ratio and packet size coefficient. Aggregation ratio is used to measure the energy saving by data aggregation, and packet size coefficient allows to evaluate the network capacity change due to data aggregation. Using these metrics, we confirm that data aggregation saves energy and capacity whatever the routing or MAC protocol is used. Secondly, to reduce the impact of sensitive raw data, we propose a data-independent aggregation method which benefits from similar data evolution and achieves better recovered fidelity. Thirdly, a property-independent aggregation function is proposed to adapt the dynamic data variations. Comparing to other functions, our proposal can fit the latest raw data better and achieve real adaptability without assumption about the application and the network topology. Finally, considering a given application, a target accuracy, we classify the forecasting aggregation functions by their performances. The networking-oriented metrics are used to measure the function performance, and a Markov Decision Process is used to compute them. Dataset characterization and classification framework are also presented to guide researcher and engineer to select an appropriate functions under specific requirements
2
Huang, Wen, and 黄文. "Opportunistic scheduling in wireless data networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B45895235.
Full text
3
Bolia, Nomesh Kulkarni Vidyadhar G. "Scheduling in wireless cellular data networks." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2780.
Full textAbstract:
Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2009.Title from electronic title page (viewed Mar. 10, 2010). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Statistics and Operations Research Operations Research." Discipline: Statistics and Operations Research; Department/School: Statistics and Operations Research.
4
Xu, Ji. "Data caching in wireless mobile networks /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?COMP%202004%20XU.
Full textAbstract:
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 57-60). Also available in electronic version. Access restricted to campus users.
5
Rasul, Aram Mohammed. "Data collection in wireless sensor networks." Thesis, University of Leicester, 2016. http://hdl.handle.net/2381/37606.
Full textAbstract:
This thesis is principally concerned with effcient energy consumption in wireless sensor networks from two distinct aspects from a theoretical point of view. The thesis addresses the issue of reducing idle listening states in a restricted tree topology to minimise energy consumption by proposing an optimisation technique: the extra-bit technique. This thesis also focuses on showing lower bounds on the optimal schedule length, which are derived for some special cases of the tree, such as a single chain, balanced chains, imbalanced chains, three and four level k-ary trees and Rhizome trees. Then, we propose an algorithm which can exactly match the lower bound for a single chain, balanced chains and Rhizome trees individually and which is a few steps away from the optimal solution for imbalanced chains. Finally, we propose the use of two frequencies to further save energy and minimize latency. Recent research has shown that significant energy improvements can be achieved in WSNs by exploiting a mobile sink for data collection via single hop communications. A mobile sink approaches the transmission range of sensors to receive their data and deposit the data at the base station. The thesis, as a second problem, focuses on the design issues of an energy efficient restricted tour construction for sink mobility. We propose two different techniques. The first one is heuristic and uses a criterion based on maximum coverage and minimum energy consumption called the "max-ratio". Although its time complexity is polynomial, this heuristic algorithm cannot always produce a good solution. As a result, we propose the sec- ond algorithm. Despite the time complexity of the second algorithm being pseudo polynomial, the optimal solution can be found if one exists. For each algorithm men- tioned, two scenarios are taken into account with regard to the transmission. In the first scenario, one assumes that there is no upper bound on the transmission range while in the second setting the nodes can adjust their transmission range between 0 and the maximum range. The algorithms have been implemented and simulated in Matlab.
6
Ostovari, Pouya. "Priority-Based Data Transmission in Wireless Networks using Network Coding." Diss., Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/360800.
Full textAbstract:
Computer and Information SciencePh.D.
With the rapid development of mobile devices technology, they are becoming very popular and a part of our everyday lives. These devices, which are equipped with wireless radios, such as cellular and WiFi radios, affect almost every aspect of our lives. People use smartphone and tablets to access the Internet, watch videos, chat with their friends, and etc. The wireless connections that these devices provide is more convenient than the wired connections. However, there are two main challenges in wireless networks: error-prone wireless links and network resources limitation. Network coding is widely used to provide reliable data transmission and to use the network resources efficiently. Network coding is a technique in which the original packets are mixed together using algebraic operations. In this dissertation, we study the applications of network coding in making the wireless transmissions robust against transmission errors and in efficient resource management. In many types of data, the importance of different parts of the data are different. For instance, in the case of numeric data, the importance of the data decreases from the most significant to the least significant bit. Also, in multi-layer videos, the importance of the packets in different layers of the videos are not the same. We propose novel data transmission methods in wireless networks that considers the unequal importance of the different parts of the data. In order to provide robust data transmissions and use the limited resources efficiently, we use random linear network coding technique, which is a type of network coding. In the first part of this dissertation, we study the application of network coding in resource management. In order to use the the limited storage of cache nodes efficiently, we propose to use triangular network coding for content distribution. We also design a scalable video-on-demand system, which uses helper nodes and network coding to provide users with their desired video quality. In the second part, we investigate the application of network coding in providing robust wireless transmissions. We propose symbol-level network coding, in which each packet is partitioned to symbols with different importance. We also propose a method that uses network coding to make multi-layer videos robust against transmission errors.
Temple University--Theses
7
Collins, Diarmuid. "Wireless Data Acquisition in Flight Test Networks." International Foundation for Telemetering, 2015. http://hdl.handle.net/10150/596417.
Full textAbstract:
ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NVThe use of wireless data networks is ubiquitous in the consumer world. They have gained significant traction due to advantages afforded by the lack of wires. These same advantages can prove valuable in Flight Test for data acquisition. Sensor nodes are ideal candidates for low bandwidth wireless networks. Located in remote, hard to reach and hostile environments, wirelessly acquiring data from such sensor can solve a number of existing issues for FTI engineers. Implementing such wireless communication introduces a number of challenges such as guaranteeing reliable transfer of the sensor data and time synchronization of the remote nodes. This paper addresses wireless sensor acquisition, the associated challenges and discusses approaches and solutions to these problems.
8
Yazar, Dogan. "RESTful Wireless Sensor Networks." Thesis, Uppsala University, Department of Information Technology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-110353.
Full textAbstract:
Sensor networks have diverse structures and generally employ proprietary protocols to gather useful information about the physical world. This diversity generates problems to interact with these sensors since custom APIs are needed which are tedious, error prone and have steep learning curve. In this thesis, I present RESThing, a lightweight REST framework for wireless sensor networks to ease the process of interacting with these sensors by making them accessible over the Web. I evaluate the system and show that it is feasible to support widely used and standard Web protocols in wireless sensor networks. Being able to integrate these tiny devices seamlessly into the global information medium, we can achieve the Web of Things.
9
Velayutham, Aravind Murugesan. "Transport Protocols for Next Generation Wireless Data Networks." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6957.
Full textAbstract:
Emerging wireless networks are characterized by increased heterogeneity in wireless access technologies as well as increased peer-to-peer communication among wireless hosts.
The heterogeneity among wireless access interfaces mainly exists because of the fact that different wireless technologies deliver different performance trade-offs.
Further, more and more infrastructure-less wireless networks such as ad-hoc networks are
emerging to address several application scenarios including military and disaster recovery. These infrastructure-less wireless networks are characterized by the peer-to-peer communication
model. In this thesis, we propose transport protocols that tackle the challenges that arise
due to the above-mentioned properties of state-of-the-art wireless data networks.
The main contributions of this work are as follows:
1. We determine the ideal nature and granularity of transport adaptation for efficient operation in heterogeneous wireless data networks by performing comprehensive experimental analysis. We then design and implement a runtime adaptive transport framework, *TP, which accommodates the capabilities of the ideal transport adaptation solution.
2. We prove that conversational transport protocols are not efficient under peer-to-peer wireless data networks. We then design and implement NCTP which is a non-conversational transport protocol.
10
Hsieh, Hung-Yun. "Addressing Network Heterogeneity and Bandwidth Scarcity in Future Wireless Data Networks." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5063.
Full textAbstract:
To provide mobile hosts with seamless and broadband wireless Internet access, two fundamental problems that need to be tackled in wireless networking are transparently supporting host mobility and effectively utilizing wireless bandwidth. The increasing heterogeneity of wireless networks and the proliferation of wireless devices, however, severely expose the limitations of the paradigms adopted by existing solutions. In this work, we explore new research directions for addressing network heterogeneity and bandwidth scarcity in future wireless data networks. In addressing network heterogeneity, we motivate a transport layer solution for transparent mobility support across heterogeneous wireless networks. We establish parallelism and transpositionality as two fundamental principles to be incorporated in designing such a transport layer solution. In addressing bandwidth scarcity, we motivate a cooperative wireless network model for scalable bandwidth utilization with wireless user population. We establish base station assistance and multi-homed peer relay as two fundamental principles to be incorporated in designing such a cooperative wireless network model. We present instantiations based on the established principles respectively, and demonstrate their performance and functionality gains through theoretic analysis, packet simulation, and testbed emulation.
11
Ramotsoela, Tsotsope Daniel. "Data aggregation using homomorphic encryption in wireless sensor networks." Diss., University of Pretoria, 2015. http://hdl.handle.net/2263/61330.
Full textAbstract:
Wireless sensor networks have become increasingly popular in many applications such as environment monitoring and law enforcement. Data aggregation is a method used to reduce network traffic but cannot be used together with conventional encryption schemes because it is not secure and introduces extra overhead. Homomorphic encryption is an encryption scheme that allows data processing on encrypted data as opposed to plaintext. It has the benefit that each intermediate node does not have to decrypt each packet, but the resulting cyphertext is usually much larger than the original plaintext. This could negatively affect system performance because the energy consumption of each node is directly proportional to the amount of data it transmits.
This study investigates the benefits and drawback of using homomorphic encryption in the aggregation process particularly in the context of scalable networks. It was found that conventional encryption outperforms the homomorphic encryption for smaller networks, but as the network size grows, homomorphic encryption starts outperforming conventional encryption. It was also found that the homomorphic encryption scheme does significantly reduce the performance of plaintext aggregation. This performance reduction will however be acceptable for most applications where security is a concern.Draadlose sensornetwerke raak toenemend meer gewild vir heelwat verskillende toepassings, soos byvoorbeeld opgewingsmonitering en wetstoepassing. Data-aggregasie is n metode wat gebruik word om netwerkverkeer te verminder, maar kan nie gebruik word saam met konvensionele enkripsie-skemas nie, omdat dit nie veilig is nie en oorhoofse koste verhoog. Homomorfiese enkripsie is n enkripsie-skema wat dataverwerking toelaat op geënkripteerde in teenstelling met gewone-teks. Dit het die voordeel dat elke intermediêre nie nodig het om elke pakkie te dekripteer nie, maar die resulterende kodeteks is gewoonlik heelwat groter as die gewone-teks. Dit kan die stelselgedrag negatief beÏnvloed omdat die energieverbruik van elke node eweredig is aan die hoeveelheid data wat dit versend. Hierdie studie ondersoek die voor- en nadele van homomorfiese enkripsie in die aggregasieproses, veral in die konteks van skaleerbare netwerke. Daar is gevind dat konvensionele enkripsie beter vaar as homomorfies enkripsie in kleiner netwerke. Die omgekeerde is waar vir groter netwerke. Dit is ook gevind dat homomorfiese enkripsie gewone-teks-aggregasie negatief beÏnvloed, maar dit word as aanvaarbaar beskou vir toepassings waar sekuriteit belangrik is.
Dissertation (MEng)--University of Pretoria, 2015.
Electrical, Electronic and Computer Engineering
Meng
Unrestricted
12
Björkstad, Per-Erik. "Reliable Data Delivery over Wireless Sensor Networks." Thesis, KTH, Reglerteknik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-106245.
Full textAbstract:
In this thesis we present ReDaR, a software and hardware environment for reliable data retrieval from multiple remotely located wireless sensor networks (WSNs). The software is programmed in Java and NesC over TinyOS, and allows for direct interaction with individual sensors using a graphical user interface running on a remote client. The hardware platform includes a WSN deployed with Telos wireless sensors. ReDaR implements a control algorithm over a real WSN, which allows to keep under control the overhead communication bandwidth between the sensors and the remote client. Specifically, we implement a control algorithm based on the extremum seeking control theory, which enables an adaptive forward error correction mechanism to ensure reliable real-time data retrieval. The amount of redundancy is controlled via a switching controller that uses a feedforward and a feedback mechanism. The switching controller ensures an optimal trade-off between maximizing the bandwidth and maximizing the quality of service. Experiments performed in our environment confirm theoretical results about performance of the controller, i.e. the feedback mechanism provides a robust controller that finds the optimum without model reliance, while the feed forward one improves the transient behavior.
13
Anantharaju, Srinath. "Resilient Data Aggregation in Wireless Sensor Networks." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-07282005-161557/.
Full textAbstract:
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.
14
Yow, Thiam Poh. "Tunneled data transmission over wireless sensor networks." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Dec%5FYow.pdf.
Full textAbstract:
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 2007.Thesis Advisor(s): McEachen, John C. ; Tummala, Murali. "December 2007." Description based on title screen as viewed on January 24, 2008. Includes bibliographical references (p. 73-74). Also available in print.
15
Vepanjeri, Lokanadha Reddy Sasi Kiran. "Data Security in Unattended Wireless Sensor Networks." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/23646.
Full textAbstract:
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.
16
Silahtar, Oguz 1978. "Error recovrery schemes in wireless data networks." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86731.
Full textAbstract:
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (leaves 76-78).
by Oguz Silahtar.
M.Eng.
17
Roy, Sankardas. "Secure data aggregation in wireless sensor networks." Fairfax, VA : George Mason University, 2008. http://hdl.handle.net/1920/3360.
Full textAbstract:
Thesis (Ph.D.)--George Mason University, 2008.Vita: p. 124. Thesis directors: Sushil Jajodia, Sanjeev Setia Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Information Technology. Title from PDF t.p. (viewed Jan. 11, 2009). Includes bibliographical references (p. 120-123). Also issued in print.
18
Stine, John Andrew. "Energy conserving protocols for wireless data networks." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3035983.
Full text
19
Alzaid, Hani Mohammed. "Secure data aggregation in wireless sensor networks." Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/41843/1/Hani_Alzaid_Thesis.pdf.
Full textAbstract:
A Wireless Sensor Network (WSN) is a set of sensors that are integrated with a physical environment. These sensors are small in size, and capable of sensing physical phenomena and processing them. They communicate in a multihop manner, due to a short radio range, to form an Ad Hoc network capable of reporting network activities to a data collection sink. Recent advances in WSNs have led to several new promising applications, including habitat monitoring, military target tracking, natural disaster relief, and health monitoring. The current version of sensor node, such as MICA2, uses a 16 bit, 8 MHz Texas Instruments MSP430 micro-controller with only 10 KB RAM, 128 KB program space, 512 KB external
ash memory to store measurement data, and is powered by two AA batteries. Due to these unique specifications and a lack of tamper-resistant hardware, devising security protocols for WSNs is complex. Previous studies show that data transmission consumes much more energy than computation. Data aggregation can greatly help to reduce this consumption by eliminating redundant data. However, aggregators are under the threat of various types of attacks. Among them, node compromise is usually considered as one of the most challenging for the security of WSNs. In a node compromise attack, an adversary physically tampers with a node in order to extract the cryptographic secrets. This attack can be very harmful depending on the security architecture of the network. For example, when an aggregator node is compromised, it is easy for the adversary to change the aggregation result and inject false data into the WSN. The contributions of this thesis to the area of secure data aggregation are manifold. We firstly define the security for data aggregation in WSNs. In contrast with existing secure data aggregation definitions, the proposed definition covers the unique characteristics that WSNs have. Secondly, we analyze the relationship between security services and adversarial models considered in existing secure data aggregation in order to provide a general framework of required security services. Thirdly, we analyze existing cryptographic-based and reputationbased secure data aggregation schemes. This analysis covers security services provided by these schemes and their robustness against attacks. Fourthly, we propose a robust reputationbased secure data aggregation scheme for WSNs. This scheme minimizes the use of heavy cryptographic mechanisms. The security advantages provided by this scheme are realized by integrating aggregation functionalities with: (i) a reputation system, (ii) an estimation theory, and (iii) a change detection mechanism. We have shown that this addition helps defend against most of the security attacks discussed in this thesis, including the On-Off attack. Finally, we propose a secure key management scheme in order to distribute essential pairwise and group keys among the sensor nodes. The design idea of the proposed scheme is the combination between Lamport's reverse hash chain as well as the usual hash chain to provide both past and future key secrecy. The proposal avoids the delivery of the whole value of a new group key for group key update; instead only the half of the value is transmitted from the network manager to the sensor nodes. This way, the compromise of a pairwise key alone does not lead to the compromise of the group key. The new pairwise key in our scheme is determined by Diffie-Hellman based key agreement.
20
Ai, Chunyu. "Energy-Efficient Data Management in Wireless Sensor Networks." Digital Archive @ GSU, 2010. http://digitalarchive.gsu.edu/cs_diss/55.
Full textAbstract:
Wireless Sensor Networks (WSNs) are deployed widely for various applications. A variety of useful data are generated by these deployments. Since WSNs have limited resources and unreliable communication links, traditional data management techniques are not suitable. Therefore, designing effective data management techniques for WSNs becomes important. In this dissertation, we address three key issues of data management in WSNs. For data collection, a scheme of making some nodes sleep and estimating their values according to the other active nodes’ readings has been proved energy-efficient. For the purpose of improving the precision of estimation, we propose two powerful estimation models, Data Estimation using a Physical Model (DEPM) and Data Estimation using a Statistical Model (DESM). Most of existing data processing approaches of WSNs are real-time. However, historical data of WSNs are also significant for various applications. No previous study has specifically addressed distributed historical data query processing. We propose an Index based Historical Data Query Processing scheme which stores historical data locally and processes queries energy-efficiently by using a distributed index tree. Area query processing is significant for various applications of WSNs. No previous study has specifically addressed this issue. We propose an energy-efficient in-network area query processing scheme. In our scheme, we use an intelligent method (Grid lists) to describe an area, thus reducing the communication cost and dropping useless data as early as possible. With a thorough simulation study, it is shown that our schemes are effective and energy- efficient. Based on the area query processing algorithm, an Intelligent Monitoring System is designed to detect various events and provide real-time and accurate information for escaping, rescuing, and evacuation when a dangerous event happened.
21
Zhuang, Zhenyun. "Application acceleration for wireless and mobile data networks." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37164.
Full textAbstract:
This work studies application acceleration for wireless and mobile data networks. The problem of accelerating application can be addressed along multiple dimensions. The first dimension is advanced network protocol design, i.e., optimizing underlying network
protocols, particulary transport layer protocol and link layer protocol.
Despite advanced network protocol design, in this work we observe that certain application behaviors can fundamentally limit the performance achievable when operating over wireless and mobile data networks. The performance difference is caused by the complex
application behaviors of these non-FTP applications. Explicitly dealing with application behaviors can improve application performance for new environments. Along this overcoming application behavior dimension, we accelerate applications by studying specific types of applications including Client-server, Peer-to-peer and Location-based applications. In exploring along this dimension, we identify a set of application behaviors that significantly affect application performance. To accommodate these application behaviors, we firstly extract general design principles that can apply to any applications whenever possible. These
design principles can also be integrated into new application designs. We also consider specific applications by applying these design principles and build prototypes to demonstrate the effectiveness of the solutions.
In the context of application acceleration, even though all the challenges belong to the two aforementioned dimensions of advanced network protocol design and overcoming application behavior are addressed, application performance can still be limited by the underlying network capability, particularly physical bandwidth. In this work, we study the possibility of speeding up data delivery by eliminating traffic redundancy present in application traffics. Specifically, we first study the traffic redundancy along multiple dimensions using traces obtained from multiple real wireless network deployments. Based on the insights obtained from the analysis, we propose Wireless Memory (WM), a two-ended AP-client solution to effectively exploit traffic redundancy in wireless and mobile environments. Application acceleration can be achieved along two other dimensions: network provision ing and quality of service (QoS). Network provisioning allocates network resources such as physical bandwidth or wireless spectrum, while QoS provides different priority to different applications, users, or data flows. These two dimensions have their respective limitations in the context of application acceleration.
In this work, we focus on the two dimensions of overcoming application behavior and Eliminating traffic redundancy to improve application performance. The contribution of this work is as follows. First, we study the problem of application acceleration for wireless and mobile data networks, and we characterize the dimensions along which to address the problem. Second, we identify that application behaviors can significantly affect application performance, and we propose a set of design principles to deal with the behaviors. We also build prototypes to conduct system research. Third, we consider traffic redundancy elimination and propose a wireless memory approach.
22
Hassanzadeh, Navid. "Scalable Data Collection for Mobile Wireless Sensor Networks." Thesis, KTH, Kommunikationsnät, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-98818.
Full textAbstract:
In the near future WSNs (wireless sensor networks) which consist of tiny wireless embedded systems will be an inseparable part of our daily lives. Data collection, collecting data from a large number of sources to one or more base stations, is a typical application for WSNs. A substantial number of data collection algorithms have been specifically designed for static scenarios while there are some scenarios in which sensor nodes are attached to intrinsically mobile objects. Generally, in such scenarios delay tolerant networking approaches have been exploited for offline data analysis. However, in-situ dta collection from mobile scenarios has received little attention. We propose Mobile Collect to address the limitations of static data collection protocols in mobile scenarios. For this purpose, Collection Tree Protocol (CTP), a de facto standard for data collection, which is implemented in Contiki-OS (Contiki Collect), has been optimized to avoid loops and to react quickly to topology changes which occur frequently in mobile scenarios. The MAC (Medium Access Control) layer in WSNs has a decisive impact on the overall performance of mobile networks in terms of power consumption, and packet delivery rate. We have evaluated Mobile Collect protocol with a receiver-initiated (A-MAC that we implemented in Contiki-OS) and a sender-initiated (Contiki-MAC) MAC protocol. Compared to the Contiki Collect and the recently proposed DYMO (Dynamic MANET On-demand) protocol, MObile Collect with Contiki-MAC shows a significant improvement in reliability while it has a slight increase in power consumption. A-MAC slightly improves reliability for sparse topologies, but has higher power consumption.
23
Ying, Yeqiu. "Synchronization and data detection in wireless sensor networks." Thesis, University of Leeds, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485187.
Full textAbstract:
Wireless'sensor networks (WSNs) have been envisioned as one of the most 'important emerging technologies that can greatly impact the world. With the recent advancement in both electronics and wireless communication networks, implementing WSNs in practical applications has become feasible and can be expected.in the near future. However, current communications protocols are not suitable for use in WSNs due to the unique characteristics and the system constraints such as low power consumption, and low computational and hardware complexity. '\. In this thesis, we focus on the physical (PRY) layer design issues including . transmission medium selection, and transceiver design. Specifically, we first study a WSN architecture with a centralized topology. Motivated by the factor that if not properly treated, carrier frequency offset (CFO) and multipath channel can cause great degradation of data detection performance in conventional carrier-based radio systems (narrow-band and wide-band systems), we address CFO and channel estimation for multiple slave sensor nodes. Relying on a unique TDMA-like training head pattern, the joint multi-user CFO and channel estimation problem can be easily decoupled. Furthermore, the joint CFO and channel estimation for each slave sensor can also be treated separately without significant performance degradation. Different CFO and channel estimators are derived and compared. Optimal training design, specifically the pilot symbols placement, for burst transmission systems is also investigated, and an equal-preamble-postamble (EPP) placement scheme is shown to be optimal. In the second half of the thesis, the emerging ultra-wideband (UWB) radio technology is investigated in the context of WSNs. We believe that this new radio technology is a strong candidate for WSN applications d?e to its unique advantages. The modulation ~d receiver schemes are stqdied and block-coded modulation and a novel noncoherent receiver are proposed for impulse radio (IR) UWB systems. The critical challenge of timing synchronization for IR-UWB signals is also studied, and a new code-assisted synchronization scheme is proposed. This semi-analog based synchronization scheme enables the usage of both coherent and noncoherent receivers, and can be executed under either blind or data-aided mode. In conclusion, this research work is expected to favorably impact the theory, design and implementation of communication transceivers for practical W8Ns.
24
Imam, Ahadul. "Data compression and visualization for wireless sensor networks." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1597773.
Full textAbstract:
A basic feature of wireless sensor networks is that transmitting data is much more expensive than processing it. Hence, data compression is really necessary to limit the amount of data transmitted within the network. In this script, we propose a data compression method suitable for wireless sensor networks. In this method, data point density is considered to keep or delete points with a region. This method is applied to the whole data set by dividing the set in blocks. One point per block will be kept which will replace the densest region. The resulting data points give the compressed form of input data. This process will cause less power consumption for wireless sensor networks while keeping the properties of actual data set. A tool is developed to test the method and compare it with other methods.
25
Mukherjee, Shubham. "Pricing and efficiency in wireless cellular data networks." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33858.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 98-101).
In this thesis, we address the problem of resource allocation in wireless cellular networks carrying elastic data traffic. A recent approach to the study of large scale engineering systems, such as communication networks, has been to apply fundamental economic principles to understand how resources can be efficiently allocated in a system despite the competing interests and selfish behavior of the users. The most common approach has been to assume that each user behaves selfishly according to a payoff function, which is the difference between his utility derived from the resources he is allocated, and the price charged by the network's manager. The network manager can influence user behavior through the price, and thereby improve the system's efficiency. While extensive analysis along these lines has been carried out for wireline networks (see, for example, [10], [7], [23], [29], [21]), the wireless environment poses a host of unique challenges. Another recent line of research for wireline networks seeks to better understand how the economic realities of data networks can impact the system's efficiency. In particular, authors have considered the case where the network manager sets prices in order to maximize profits rather than achieve efficient resource allocation; see [1] and references therein.
(cont.) In this thesis, we make three contributions. Using a game theoretic framework, we show that rate-based pricing can lead to an efficient allocation of resources in wireless cellular networks carrying elastic traffic. Second, we use the game theoretic equilibrium notions as motivation for a cellular rate control algorithm, and examine its convergence and stability properties. Third, we study the impact of a profit-maximizing price setter on the system's efficiency. In particular, we show the surprising result that for a broad class of utility functions, including logarithmic and linear utilities, the profit maximizing price results in efficiency.
by Shubham Mukherjee.
S.M.
26
Murshed, Md Golam. "Energy efficient data gathering in wireless sensor networks." Thesis, University of Aberdeen, 2013. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=210783.
Full textAbstract:
Along with the rapid growth of Wireless Sensor Networks, a wide range of challenges have come to existence to make the network more robust and versatile. Gaining energy efficiency and maximizing network lifetime are the most important of all that can affect the performance of the network directly. In this thesis, a number of research aspects related to energy efficient data gathering have been investigated and some promising proposals are presented. In large, hierarchical multi-hop Wireless Sensor Networks, power consumption characteristics of the static sensor nodes and data traffic distribution across the network are largely determined by the node position and the adopted routing protocol. In this thesis, these phenomena of the network are addressed analytically and we proposed some methods to divide the monitoring field into partitions that act as the basis for even load distribution in the network. We proposed an algorithm to calculate the area of the partitions that exploits the energy efficient features of optimal transmission range. The partition works as the bedrock of the other proposals in this thesis. Considering the influential factors of the proximity and the recent state of the network, we also developed a routing protocol that minimises over all energy consumption of the network and is able to dynamically select a route to the sink. Further, we proposed a rotational order for data gathering scheme that works along with the routing protocol to ensure load balancing and to alleviate data congestion around the sink. Clustered organization of the nodes in sensor networks can further save energy consumption and facilitates scope for better network management. In this thesis, we address the fact that equal sized clusters can cause unbalanced data traffic around the sink. So, we propose a method to calculate suitable cluster radii in different regions of the monitoring field in order to form clusters of different sizes. To ensure unequal clusters in the field, a cluster construction procedure is also proposed targeting minimal data generation, minimal energy consumption and providing capacity for reliability preservation. Furthermore, the notion of redundant nodes and the outlines of a possible solution to identify and deactivate redundant nodes are explained in this thesis. Since the clusterheads play an important role as coordinators in the clusters, it is vital that there is a clusterhead in every cluster all the time. In this thesis, a message optimal and distributed leader election algorithm is proposed to select a new clusterhead in case of unexpected and unnoticed failure of a clusterhead node. Detailed analysis and simulation of the proposed methods clarify the effectiveness of the research. In comparison with other methods of similar kind, our methods confirm better balanced energy dissipation, energy efficient route selection, message optimal clusterhead selection and prolonged lifetime of the network.
27
Leinonen, M. (Markus). "Distributed compressed data gathering in wireless sensor networks." Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526220451.
Full textAbstract:
Abstract Wireless sensor networks (WSNs) consisting of battery-powered sensors are increasingly deployed for a myriad of Internet of Things applications, e.g., environmental, industrial, and healthcare monitoring. Since wireless access is typically the main contributor to battery usage, minimizing communications is crucial to prolong network lifetime and improve user experience. The objective of this thesis is to develop and analyze energy-efficient distributed compressed data acquisition techniques for WSNs. The thesis proposes four approaches to conserve sensors' energy by minimizing the amount of information each sensor has to transmit to meet given application requirements. The first part addresses a cross-layer design to minimize the sensors’ sum transmit power via joint optimization of resource allocation and multi-path routing. A distributed consensus optimization based algorithm is proposed to solve the problem. The algorithm is shown to have superior convergence compared to several baselines. The remaining parts deal with compressed sensing (CS) of sparse/compressible sources. The second part focuses on the distributed CS acquisition of spatially and temporally correlated sensor data streams. A CS algorithm based on sliding window and recursive decoding is developed. The method is shown to achieve higher reconstruction accuracy with fewer transmissions and less decoding delay and complexity compared to several baselines, and to progressively refine past estimates. The last two approaches incorporate the quantization of CS measurements and focus on lossy source coding. The third part addresses the distributed quantized CS (QCS) acquisition of correlated sparse sources. A distortion-rate optimized variable-rate QCS method is proposed. The method is shown to achieve higher distortion-rate performance than the baselines and to enable a trade-off between compression performance and encoding complexity via the pre-quantization of measurements. The fourth part investigates information-theoretic rate-distortion (RD) performance limits of single-sensor QCS. A lower bound to the best achievable compression — defined by the remote RD function (RDF) — is derived. A method to numerically approximate the remote RDF is proposed. The results compare practical QCS methods to the derived limits, and show a novel QCS method to approach the remote RDFTiivistelmä Patterikäyttöisistä antureista koostuvat langattomat anturiverkot yleistyvät esineiden internetin myötä esim. ympäristö-, teollisuus-, ja terveydenhoitosovelluksissa. Koska langaton tiedonsiirto kuluttaa merkittävästi energiaa, kommunikoinnin minimointi on elintärkeää pidentämään verkon elinikää ja parantamaan käyttäjäkokemusta. Väitöskirjan tavoitteena on kehittää ja analysoida energiatehokkaita hajautettuja pakattuja datankeruumenetelmiä langattomiin anturiverkkoihin. Työssä ehdotetaan neljä lähestymistapaa, jotka säästävät anturien energiaa minimoimalla se tiedonsiirron määrä, mikä vaaditaan täyttämään sovelluksen asettamat kriteerit. Väitöskirjan ensimmäinen osa tarkastelee protokollakerrosten yhteissuunnittelua, jossa minimoidaan anturien yhteislähetysteho optimoimalla resurssiallokaatio ja monitiereititys. Ratkaisuksi ehdotetaan konsensukseen perustuva hajautettu algoritmi. Tulokset osoittavat algoritmin suppenemisominaisuuksien olevan verrokkejaan paremmat. Loppuosat keskittyvät harvojen lähteiden pakattuun havaintaan (compressed sensing, CS). Toinen osa keskittyy tila- ja aikatasossa korreloituneen anturidatan hajautettuun keräämiseen. Työssä kehitetään liukuvaan ikkunaan ja rekursiiviseen dekoodaukseen perustuva CS-algoritmi. Tulokset osoittavat menetelmän saavuttavan verrokkejaan korkeamman rekonstruktiotarkkuuden pienemmällä tiedonsiirrolla sekä dekoodausviiveellä ja -kompleksisuudella ja kykenevän asteittain parantamaan menneitä estimaatteja. Työn viimeiset osat sisällyttävät järjestelmämalliin CS-mittausten kvantisoinnin keskittyen häviölliseen lähdekoodaukseen. Kolmas osa käsittelee hajautettua korreloitujen harvojen signaalien kvantisoitua CS-havaintaa (quantized CS, QCS). Työssä ehdotetaan särön ja muuttuvan koodinopeuden välisen suhteen optimoiva QCS-menetelmä. Menetelmällä osoitetaan olevan verrokkejaan parempi pakkaustehokkuus sekä kyky painottaa suorituskyvyn ja enkooderin kompleksisuuden välillä mittausten esikvantisointia käyttäen. Neljäs osa tutkii informaatioteoreettisia, koodisuhde-särösuhteeseen perustuvia suorituskykyrajoja yhden anturin QCS-järjestelmässä. Parhaimmalle mahdolliselle pakkaustehokkuudelle johdetaan alaraja, sekä kehitetään menetelmä sen numeeriseen arviointiin. Tulokset vertaavat käytännön QCS-menetelmiä johdettuihin rajoihin, ja osoittavat ehdotetun QCS-menetelmän saavuttavan lähes optimaalinen suorituskyky
28
Zinchenko, I. S. "Technology of data transfer in wireless sensor networks." Thesis, Sumy State University, 2016. http://essuir.sumdu.edu.ua/handle/123456789/45887.
Full textAbstract:
It has been over a decade since then, when we started intensive scientific and technological research of possibilities of using sensors together with the wireless network. The result was the creation of new types of telecommunications networks, wireless sensor networks (WSN) is a new promising technology, which are applied and executed large-scale projects for different industries and military systems.
29
Miao, Ye. "Efficient data gathering solutions for wireless sensor networks." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/808106/.
Full textAbstract:
Wireless Sensor Networks (WSNs) support a variety of data collection scenarios and have profound effects on both military and civil applications, such as environmental monitoring, traffic surveillance and tactical military monitoring. Design of efficient data collection algorithms is important yet still challenging due to the distinguished characteristics of WSNs: (i) The large number of sensor nodes may cause severe unbalanced traffic through the network due to the concentration of data traffic towards the sinks and the intersection of multihop routes. (ii) Sensor nodes are limited in power, computational capability and storage capacity, which requires careful resource management using energy efficient schemes. (iii) WSNs are typically application-specific, and the design requirements of networks change with different applications. This thesis presents the following three contributions to the literature of efficient data collection in WSNs: First, we proposed a unified solution for gateway and in-network traffic load balancing in multihop data collection scenarios. We combined multiple path metrics (path residual bandwidth, end-to-end delay and path reliability) and gateway conditions (gateway utilization) in a unified path quality metric. The strategy is to probabilistically choose alternative path and adaptively modify the path switch probability based on the independent decisions made by the sensor nodes. Second, we formulated the delay aware energy efficient data collection with mobile sink and virtual multiple-input multiple-output (VMIMO) technique problem and proposed a weighted revenue based algorithm to approximate the optimal solution. The aim is to achieve full utilization of VMIMO technique to minimize the network energy consumption with consideration of bounded sink moving time. In order to explore the trade-off between overall network consumption and data collection latency, we combined the VMIMO utilization, and sink moving tour length into a weighted metric. Third, we established an minimization model for the total data collection latency in multihop data collection scenarios with bounded hop distance and limited buffer storage. To approximate the optimal solution, we developed a multihop weighted revenue algorithm. The strategy is to jointly consider data uploading time and sink moving time to optimize the total data collection time. In order to increase the time saving due to concurrent data uploading, we balanced the number of associated nodes of the compatible sensors.
30
Medlej, Maguy. "Big data management for periodic wireless sensor networks." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2029/document.
Full textAbstract:
Les recherches présentées dans ce mémoire s’inscrivent dans le cadre des réseaux decapteurs périodiques. Elles portent sur l’étude et la mise en oeuvre d’algorithmes et de protocolesdistribués dédiés à la gestion de données volumineuses, en particulier : la collecte, l’agrégation etla fouille de données. L’approche de la collecte de données permet à chaque noeud d’adapter sontaux d’échantillonnage à l’évolution dynamique de l’environnement. Par ce modèle le suréchantillonnageest réduit et par conséquent la quantité d’énergie consommée. Elle est basée surl’étude de la dépendance de la variance de mesures captées pendant une même période voirpendant plusieurs périodes différentes. Ensuite, pour sauvegarder plus de l’énergie, un modèled’adpatation de vitesse de collecte de données est étudié. Ce modèle est basé sur les courbes debézier en tenant compte des exigences des applications. Dans un second lieu, nous étudions unetechnique pour la réduction de la taille de données massive qui est l’agrégation de données. Lebut est d’identifier tous les noeuds voisins qui génèrent des séries de données similaires. Cetteméthode est basée sur les fonctions de similarité entre les ensembles de mesures et un modèle defiltrage par fréquence. La troisième partie est consacrée à la fouille de données. Nous proposonsune adaptation de l’approche k-means clustering pour classifier les données en clusters similaires,d’une manière à l’appliquer juste sur les préfixes des séries de mesures au lieu de l’appliquer auxséries complètes. Enfin, toutes les approches proposées ont fait l’objet d’études de performancesapprofondies au travers de simulation (OMNeT++) et comparées aux approches existantes dans lalittératureThis thesis proposes novel big data management techniques for periodic sensor networksembracing the limitations imposed by wsn and the nature of sensor data. First, we proposed anadaptive sampling approach for periodic data collection allowing each sensor node to adapt itssampling rates to the physical changing dynamics. It is based on the dependence of conditionalvariance of measurements over time. Then, we propose a multiple level activity model that usesbehavioral functions modeled by modified Bezier curves to define application classes and allowfor sampling adaptive rate. Moving forward, we shift gears to address the periodic dataaggregation on the level of sensor node data. For this purpose, we introduced two tree-based bilevelperiodic data aggregation techniques for periodic sensor networks. The first one look on aperiodic basis at each data measured at the first tier then, clean it periodically while conservingthe number of occurrences of each measure captured. Secondly, data aggregation is performedbetween groups of nodes on the level of the aggregator while preserving the quality of theinformation. We proposed a new data aggregation approach aiming to identify near duplicatenodes that generate similar sets of collected data in periodic applications. We suggested the prefixfiltering approach to optimize the computation of similarity values and we defined a new filteringtechnique based on the quality of information to overcome the data latency challenge. Last butnot least, we propose a new data mining method depending on the existing K-means clusteringalgorithm to mine the aggregated data and overcome the high computational cost. We developeda new multilevel optimized version of « k-means » based on prefix filtering technique. At the end,all the proposed approaches for data management in periodic sensor networks are validatedthrough simulation results based on real data generated by periodic wireless sensor network
31
Wang, Rui. "Resource allocation in high data-rate wireless networks /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?ECED%202008%20WANGR.
Full text
32
Le, Dinh Tuan Computer Science & Engineering Faculty of Engineering UNSW. "Data reliability control in wireless sensor networks for data streaming applications." Publisher:University of New South Wales. Computer Science & Engineering, 2009. http://handle.unsw.edu.au/1959.4/43328.
Full textAbstract:
This thesis contributes toward the design of a reliable and energy-efficient transport system for Wireless Sensor Networks. Wireless Sensor Networks have emerged as a vital new area in networking research. In many Wireless Sensor Network systems, a common task of sensor nodes is to sense the environment and send the sensed data to a sink node. Thus, the effectiveness of a Wireless Sensor Network depends on how reliably the sensor nodes can deliver their sensed data to the sink. However, the sensor nodes are susceptible to loss for various reasons when there are dynamics in wireless transmission medium, environmental interference, battery depletion, or accidentally damage, etc. Therefore, assuring reliable data delivery between the sensor nodes and the sink in Wireless Sensor Networks is a challenging task. The primary contributions of this thesis include four parts. First, we design, implement, and evaluate a cross-layer communication protocol for reliable data transfer for data streaming applications in Wireless Sensor Networks. We employ reliable algorithms in each layer of the communication stack. At the MAC layer, a CSMA MAC protocol with an explicit hop-by-hop Acknowledgment loss recovery is employed. To ensure the end-to-end reliability, the maximum number of retransmissions are estimated and used at each sensor node. At the transport layer, an end-to-end Negative Acknowledgment with an aggregated positive Acknowledgment mechanism is used. By inspecting the sequence numbers on the packets, the sink can detect which packets were lost. In addition, to increase the robustness of the system, a watchdog process is implemented at both base station and sensor nodes, which enable them to power cycle when an unexpected fault occurs. We present extensive evaluations, including theoretical analysis, simulations, and experiments in the field based on Fleck-3 platform and the TinyOS operating system. The designed network system has been working in the field for over a year. The results show that our system is a promising solution to a sustainable irrigation system. Second, we present the design of a policy-based Sensor Reliability Management framework for Wireless Sensor Networks called SRM. SRM is based on hierarchical management architecture and on the policy-based network management paradigm. SRM allows the network administrators to interact with the Wireless Sensor Network via the management policies. SRM also provides a self-control capability to the network. This thesis restricts SRM to reliability management, but the same framework is also applicable for other management services by providing the management policies. Our experimental results show that SRM can offer sufficient reliability to the application users while reducing energy consumption by more than 50% compared to other approaches. Third, we propose an Energy-efficient and Reliable Transport Protocol called ERTP, which is designed for data streaming applications in Wireless Sensor Networks. ERTP is an adaptive transport protocol based on statistical reliability that ensures the number of data packets delivered to the sink exceeds the defined threshold while reducing the energy consumption. Using a statistical reliability metric when designing a reliable transport protocol guarantees the delivery of adequate information to the users, and reduces energy consumption when compared to the absolute reliability. ERTP uses hop-by-hop Implicit Acknowledgment with a dynamically updated retransmission timeout for packet loss recovery. In multihop wireless networks, the transmitter can overhear a forwarding transmission and interpret it as an Implicit Acknowledgment. By combining the statistical reliability and the hop-by-hop Implicit Acknowledgment loss recovery, ERTP can offer sufficient reliability to the application users with minimal energy expense. Our extensive simulations and experimental evaluations show that ERTP can reduce energy consumption by more than 45% when compared to the state-of- the-art protocol. Consequently, sensor nodes are more energy-efficient and the lifespan of the unattended Wireless Sensor Network is increased. In Wireless Sensor Networks, sensor node failures can create network partitions or coverage loss which can not be solved by providing reliability at higher layers of the protocol stack. In the final part of this thesis, we investigate the problem of maintaining the network connectivity and coverage when the sensor nodes are failed. We consider a hybrid Wireless Sensor Network where a subset of the nodes has the ability to move at a high energy expense. When a node has low remaining energy (dying node) but it is a critical node which constitutes the network such as a cluster head, it will seek a replacement. If a redundant node is located in the transmission range of the dying node and can fulfill the network connectivity and coverage requirement, it can be used for substitution. Otherwise, a protocol should be in place to relocate the redundant sensor node for replacement. We propose a distributed protocol for Mobile Sensor Relocation problem called Moser. Moser works in three phases. In the first phase, the dying node determines if network partition occurs, finds an available mobile node, and asks for replacement by using flooding algorithm. The dying node also decides the movement schedule of the available mobile node based on certain criteria. The second phase of the Moser protocol involves the actual movement of the mobile nodes to approach the location of the dying node. Finally, when the mobile node has reached the transmission of the dying node, it communicates to the dying nodes and moves to a desired location, where the network connectivity and coverage to the neighbors of the dying nodes are preserved.
33
Hung, Ka-Lok. "The fair data collection problem in wireless sensor networks /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?COMP%202006%20HUNG.
Full text
34
Diaz-Anadon, Mario Orne. "Scheduling and data aggregation for periodic data gathering in wireless sensor networks." Thesis, Imperial College London, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.537561.
Full text
35
Chen, Jian. "Efficient multi-resolution data dissemination in wireless sensor networks." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2542.
Full textAbstract:
A large-scale distributed wireless sensor network is composed of a large collection
of small low-power, unattended sensing devices equipped with limited memory,
processors, and short-range wireless communication. The network is capable of controlling
and monitoring ambient conditions, such as temperature, movement, sound,
light and others, and thus enable smart environments. Energy efficient data dissemination
is one of the fundamental services in large-scale wireless sensor networks.
Based on the study of the data dissemination problem, we propose two efficient data
dissemination schemes for two categories of applications in large-scale wireless sensor
networks. In addition, our schemes provide spatial-based multi-resolution data dissemination
for some applications to achieve further energy efficiency. Analysis and
simulation results are given to show the performance of our schemes in comparison
with current techniques.
36
Rodhe, Ioana. "Query authentication and data confidentiality in wireless sensor networks." Licentiate thesis, Uppsala universitet, Avdelningen för datorteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-85854.
Full textAbstract:
In this thesis we consider different aspects of security in sensor networks, in particular query authentication and confidential data aggregation. Authenticating the queries is important so attackers cannot modify existing queries because this would lead to wrong readings; or insert new queries into the network because this would lead to waste of energy. When answering to queries, in-network aggregation in sensor networks is an efficient way to save energy. Nevertheless, node capture in hostile environments require protocols for data aggregation where the intermediate nodes contribute with their own values to the aggregated data without getting access to it. Our contributions are two protocols for query authentication and confidential data aggregation together with a common layered key distribution scheme. Both static and mobile base stations are supported. The proposed protocols use symmetric cryptography, which is preferred in sensor networks because of the sensor’s limited computational power, energy supply and memory storage. The results from our simulations show that, if an attacker captures a small number of nodes, the attacker can only introduce unauthorized queries into a limited part of the network and can only get access to a small part of the data that is aggregated into the network.WISENET
37
Wang, Li, and 王立. "Channel adaptive fair queueing in wireless packet data networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31226802.
Full text
38
Li, Hongxing, and 李宏兴. "Optimal data dissemination in stochastic and arbitrary wireless networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B4832971X.
Full textAbstract:
Data dissemination among wireless devices is an essential application in wireless networks. In contrast to its wired counterparts which have more stable network settings, wireless networks are subject to network dynamics, such as variable network topology, channel availability and capacity, which are due to user mobility, signal collision, random channel fading and scattering, etc. Network dynamics complicate the protocol design for optimal data disseminations. Although the topic has been intensively discussed for many years, existing solutions are still not completely satisfactory, especially for stochastic or arbitrary networks. In this thesis, we address optimal data dissemination in both stochastic and arbitrary wireless networks, using techniques of Lyapunov optimization, graph theory, network coding, multi-resolution coding and successive interference cancellation.
We first discuss the maximization of time-averaged throughput utility over a long run for unicast and multirate multicast, respectively, in stochastic wireless networks without probing into the future. For multi-session unicast communications, a utility-maximizing cross-layer design, composed of joint end-to-end rate control, routing, and channel allocation, is proposed for cognitive radio networks with stochastic primary user occupations. Then, we study optimal multirate multicast to receivers with non-uniform receiving rates, also making dynamic cross-layer decisions, in a general wireless network with both a timevarying topology and random channel capacities, by utilizing random linear network coding and multi-resolution coding. In both solutions, we assume users are selfish and prefer only to relay data for others with strong social ties. Such social selfishness of users is a new constraint in network protocol design. Its impact on efficient data dissemination in wireless networks is largely unstudied, especially under stochastic settings. Lyapunov optimization is applied in our protocol design achieving close-to-optimal utilities.
Next, we turn to latency-minimizing data aggregation in wireless sensor networks having arbitrary network topologies under the physical interference model. Different from our effort for stochastic networks where we target at time-averaged optimality over a long run, the objective here is to minimize the time-span to accomplish one round of aggregation scheduling for all sensors in an arbitrary topology. This problem is NP-hard, involving both aggregation tree construction and collision-free link scheduling. The current literature mostly considers the protocol interference model, which has been shown to be less practical than the physical interference model in characterizing the interference relations in the real world. A distributed solution under the physical interference model is challenging since cumulative interferences from all concurrently transmitting devices need to be well measured. In this thesis, we present a distributed aggregation protocol with an improved approximation ratio as compared with previous work. We then discuss the tradeoff between aggregation latency and energy consumption for arbitrary topologies when the successive interference cancellation technique is in force. Another distributed algorithm is introduced with asymptotic optimality in both aggregation latency and latency-energy tradeoff.
Through theoretical analysis and empirical study, we rigorously examine the optimality of our protocols comparing with both the theoretical optima and existing solutions.published_or_final_version
Computer Science
Doctoral
Doctor of Philosophy
39
Shum, L. L. "Topology control and data handling in wireless sensor networks." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/18577/.
Full textAbstract:
Our work in this thesis have provided two distinctive contributions to WSNs in the areas of data handling and topology control. In the area of data handling, we have demonstrated a solution to improve the power efficiency whilst preserving the important data features by data compression and the use of an adaptive sampling strategy, which are applicable to the specific application for oceanography monitoring required by the SECOAS project. Our work on oceanographic data analysis is important for the understanding of the data we are dealing with, such that suitable strategies can be deployed and system performance can be analysed. The Basic Adaptive Sampling Scheduler (BASS) algorithm uses the statistics of the data to adjust the sampling behaviour in a sensor node according to the environment in order to conserve energy and minimise detection delay. The motivation of topology control (TC) is to maintain the connectivity of the network, to reduce node degree to ease congestion in a collision-based medium access scheme; and to reduce power consumption in the sensor nodes. We have developed an algorithm Subgraph Topology Control (STC) that is distributed and does not require additional equipment to be implemented on the SECOAS nodes. STC uses a metric called subgraph number, which measures the 2-hops connectivity in the neighbourhood of a node. It is found that STC consistently forms topologies that have lower node degrees and higher probabilities of connectivity, as compared to k-Neighbours, an alternative algorithm that does not rely on special hardware on sensor node. Moreover, STC also gives better results in terms of the minimum degree in the network, which implies that the network structure is more robust to a single point of failure. As STC is an iterative algorithm, it is very scalable and adaptive and is well suited for the SECOAS applications.
40
Ekonomou, Elias. "Improvements to data transportation security in wireless sensor networks." Thesis, University of Salford, 2010. http://usir.salford.ac.uk/26649/.
Full textAbstract:
Wireless Sensor Networks (WSNs) are computer networks consisting of miniaturised electronic devices that aim to gather and report information about their environment. The devices are limited in computational, data storage and communication ability. Furthermore, the devices communicate via a wireless, unregulated medium and usually operate on finite power sources. Security in Wireless Sensor Networks is the research area that seeks to provide adequate and energy-efficient security mechanisms for WSNs. Such provision is required in order to increase their range of possible applications and allow them to be deployed in critical and valuable environments. Existing security mechanisms for larger computer networks are inappropriate since they were not designed for the resourceconstrained environment of WSNs. There are some purpose-built solutions but this research has found potential security or efficiency problems with each of them. This thesis contributes SecRose, a security mechanism for the data-transportation layer of Wireless Sensor Networks. The solution attempts to provide higher level of security than currently provided, without introduction of significant energy overheads and by retaining backwards compatibility. SecRose achieves its security objectives by introducing a number of innovations and improvements. SecRose innovates in the provision of freshness and semantic security by altering the secret cryptographic keys. The process is managed at the transportation level by the basic key management mechanism. The integrity and safety of the key-changing operation is achieved by authenticating all packets and their acknowledgements. This behaviour contrasts with other proposals, which are based on openly transmitted Initialisation Vectors, and allows SecRose to provide better security than most of them, including TinySec, the accepted standard. In addition, measurements show that SecRose provides better energy-efficiency than other proposals. In particular, the solution requires less energy than TinySec in all cases and it can even be more efficient than the base Operating System, the TinyOS, which does not provide any security at all.
41
Chen, Jiwei. "Efficient data transfer and congestion control in wireless networks." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1500089791&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Full text
42
Chen, Mo. "Data compression for inference tasks in wireless sensor networks." Diss., Online access via UMI:, 2006.
Find full textAbstract:
Thesis (Ph. D.)--State University of New York at Binghamton, Department of Electrical Engineering, Thomas J. Watson School of Engineering and Applied Science, 2006.Includes bibliographical references.
43
Taban, Gelareh. "Secure and private data aggregation in wireless sensor networks." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8884.
Full textAbstract:
Thesis (Ph. D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
44
Tall, Hamadoun. "Load balancing in multichannel data collection wireless sensor networks." Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC006/document.
Full textAbstract:
Les Réseaux de Capteurs Sans Fil (RCSF) sont de plus en plus exploités par des applications diverses grâce à leur facilité de déploiement et d’auto-configuration. Les applications de collecte de données qui utilisent les RCSF ont souvent un profil convergecast : l’ensemble des données récoltées par tous les capteurs du réseau sont acheminées vers un puits de collecte, grâce à une communication multi-saut. Pendant l’acheminement des données des nœuds de collecte vers le puits, des goulots d’étranglement sont fréquemment observés, principalement au voisinage du puits. Cela est du à la congestion et au phénomène d’entonnoir couramment observé sur le trafic de données ayant un profile convergecast. Outre un risque accru de collision, cela entraîne le débordement des files d’attente des nœuds concernés conduisant à des pertes de données. Cette perte réduit le taux de livraison au puits entraînant une baisse du débit du réseau. Afin de réduire ces pertes et de permettre un meilleur taux de livraison au puits, le trafic doit être équitablement réparti au niveau de chaque saut pendant l’acheminement. Dans cette thèse, nous avons d’une part proposé S-CoLBA (Single channel Collaborative Load Balancing Algorithm), un protocole mono-canal de routage dynamique avec équilibrage de la charge. Sa métrique de routage est basée sur le délais moyen d’accès au medium radio par nœud. Chaque nœud choisit comme prochain saut à destination du puits, un de ses voisins ayant le délais d’accès le plus court. S-CoLBA intègre également une surveillance permanente des files d’attente des nœuds afin de prévenir la congestion et d’éviter le débordement de ces files. D’autre part, nous avons adapté S-CoLBA pour le rendre utilisable dans un réseau multicanal. Cette version du protocole s’appelle M-CoLBA (pour Mulitchannel CoLBA). M-CoLBA évite la congestion en équilibrant la charge grâce à une répartition du trafic au niveau de chaque saut du réseau. Dans un réseau multicanal, le problème de support de diffusion se pose. M-CoLBA introduit des périodes de synchronisations où tous les nœuds utilisent le même canal pour échanger les informations de routage. Ces périodes de synchronisation contribuent à allonger les délais de bout en bout des paquets. Nous avons ainsi optimisé M-CoLBA en "surchargeant" les acquittements des trames avec les informations de routage ( piggybacking) et les états des files d’attente. Cela évite de passer par des périodes de synchronisation pour diffuser ces informations. Cette version optimisée s’appelle ABORt ( Acknowledgement-Based opportunistic Routing protocol). Dans un cas de trafic de type convergecast, ABORt induit une diversité des routes prises par les données collectées, ce qui est bénéfique à la quantité de données transportées et à la robustesse de la solution. Les contributions ont été évaluées par simulation et expérimentation dans un réseau monocanal et multicanal. Les résultats montrent que nos contributions améliorent le taux de livraison des données au puits, optimisent le délais de bout en bout et réduisent la quantité de trafic de contrôle comparé à des solutions déjà existantesThe popularity of wireless sensor networks (WSNs) is increasing due to their ease ofdeployment and auto-configuration capabilities. They are used in different applica-tion domains including data collection with convergecast scenarios. In convergecast,all data collected in the network is destined to one common node usually called thesink. In case of high carried traffic load and depending on the used routing policy,this many-to-one data collection leads to congestion and queue overflow mainly innodes located near the sink. Congestion and queue overflow reduce delivery ratiothat negatively affects the network efficiency.Wireless sensor nodes are resource constrained devices with limited buffers sizeto store and forward data to the sink. Introducing multichannel communication inWSNs helps to increase the carried traffic load thanks to allowing parallel data trans-mission and reduction of contention and interference. With high traffic load, thenumber of data packets travelling from leaf nodes towards the sink becomes higher.In case the routing scheme does not balance the traffic load, it will be unfairly dis-tributed between forwarding nodes. Thus, nodes that are in part of the routing will beoverloaded while others are less used. Overloaded nodes increase the risk of conges-tion and queue overflow leading to data loss that reduces the throughput. Therefore,we need to couple the routing protocols with traffic load balancing scheme in hightraffic load network scenarios.The goal of this thesis is to propose an efficient routing solution to prevent con-gestion and queue overflow in high data rate convergecast WSNs, in such a way, tooptimize data delivery ratio at the sink node.On the one hand, we proposed a single channel traffic load balancing routingprotocol, named S-CoLBA (Single channel Collaborative Load balancing routing).It relies on data queueing delay metric and best score (according to the value of themetric) next hop neighbors to fairly distribute traffic load in per hop basis in the net-work. Since the carried traffic load increases in multichannel communication, onthe other hand, we adapted our contribution to cope with multichannel WSNs andwe named it as Multichannel CoLBA (M-CoLBA). As broadcasting information isnot straightforward in multichannel, we optimize M-CoLBA to use piggybackingscheme for routing information sharing in the network. This enhanced version iscalled ABORt for Acknowledgement-Based opportunistic Routing protocol and re-lies on ACK frames to share routing information. Doing so helps to optimize dataframe end-to-end delay and to reduce the transmitted beacons in the network. ABORtfairly distributes traffic load in the network and avoids congestion and queue over-flow.We evaluated the performance of our contributions in both simulation using Con-tiki OS Cooja simulator and experiment (only for S-CoLBA) on TelosB motes. Ob-tained results in both simulation and experiment confirm the efficiency of our routingprotocols in term of packet delivery ratio and queue overflow compared to some ex-isting routing protocols in the literature
45
Moussa, Mohamed Ali. "Data gathering and anomaly detection in wireless sensors networks." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1082/document.
Full textAbstract:
L'utilisation des réseaux de capteurs sans fil (WSN) ne cesse d'augmenter au point de couvrir divers domaines et applications. Cette tendance est supportée par les avancements techniques achevés dans la conception des capteurs, qui ont permis de réduire le coût ainsi que la taille de ces composants. Toutefois, il reste plusieurs défis qui font face au déploiement et au bon fonctionnement de ce type de réseaux et qui parviennent principalement de la limitation des ressources de capteurs ainsi de l'imperfection des données collectées. Dans cette thèse, on adresse le problème de collecte de données et de détection d'anomalies dans les réseaux de capteurs. Nous visons à assurer ces deux fonctionnalités tout en économisant l'utilisation des ressources de capteurs et en prolongeant la durée de vie de réseaux. Tout au long de ce travail, nous présentons plusieurs solutions qui permettent une collecte efficace de données de capteurs ainsi que une bonne détection des éventuelles anomalies. Dans notre première contribution, nous décrivons une solution basée sur la technique Compressive Sensing (CS) qui permet d'équilibrer le trafic transmis par les nœuds dans le réseau. Notre approche diffère des solutions existantes par la prise en compte de la corrélation temporelle ainsi que spatiale dans le processus de décompression des données. De plus, nous proposons une nouvelle formulation pour détecter les anomalies. Les simulations réalisées sur des données réelles prouvent l'efficacité de notre approche en termes de reconstruction de données et de détection d'anomalies par rapport aux approches existantes. Pour mieux optimiser l'utilisation des ressources de WSNs, nous proposons dans une deuxième contribution une solution de collecte de données et de détection d'anomalies basée sur la technique Matrix Completion (MC) qui consiste à transmettre un sous ensemble aléatoire de données de capteurs. Nous développons un algorithme qui estime les mesures manquantes en se basant sur plusieurs propriétés des données. L'algorithme développé permet également de dissimuler les anomalies de la structure normale des données. Cette solution est améliorée davantage dans notre troisième contribution, où nous proposons une formulation différente du problème de collecte de données et de détection d'anomalies. Nous reformulons les connaissances a priori sur les données cibles par des contraintes convexes. Ainsi, les paramètres impliqués dans l'algorithme développé sont liés a certaines propriétés physiques du phénomène observé et sont faciles à ajuster. Nos deux approches montrent de bonnes performances en les simulant sur des données réelles. Enfin, nous proposons dans la dernière contribution une nouvelle technique de collecte de données qui consiste à envoyer que les positions les plus importantes dans la représentation parcimonieuse des données uniquement. Nous considérons dans cette approche le bruit qui peut s'additionner aux données reçues par le nœud collecteur. Cette solution permet aussi de détecter les pics dans les mesures prélevées. En outre, nous validons l'efficacité de notre solution par une analyse théorique corroborée par des simulations sur des données réellesThe use of Wireless Sensor Networks (WSN)s is steadily increasing to cover various applications and domains. This trend is supported by the technical advancements in sensor manufacturing process which allow a considerable reduction in the cost and size of these components. However, there are several challenges facing the deployment and the good functioning of this type of networks. Indeed, WSN's applications have to deal with the limited energy, memory and processing capacities of sensor nodes as well as the imperfection of the probed data. This dissertation addresses the problem of collecting data and detecting anomalies in WSNs. The aforementioned functionality needs to be achieved while ensuring a reliable data quality at the collector node, a good anomaly detection accuracy, a low false alarm rate as well as an efficient energy consumption solution. Throughout this work, we provide different solutions that allow to meet these requirements. Foremost, we propose a Compressive Sensing (CS) based solution that allows to equilibrate the traffic carried by nodes regardless their distance from the sink. This solution promotes a larger lifespan of the WSN since it balances the energy consumption between sensor nodes. Our approach differs from existing CS-based solutions by taking into account the sparsity of sensory representation in the temporal domain in addition to the spatial dimension. Moreover, we propose a new formulation to detect aberrant readings. The simulations carried on real datasets prove the efficiency of our approach in terms of data recovering and anomaly detection compared to existing solutions. Aiming to further optimize the use of WSN resources, we propose in our second contribution a Matrix Completion (MC) based data gathering and anomaly detection solution where an arbitrary subset of nodes contributes at the data gathering process at each operating period. To fill the missing values, we mainly relay on the low rank structure of sensory data as well as the sparsity of readings in some transform domain. The developed algorithm also allows to dissemble anomalies from the normal data structure. This solution is enhanced in our third contribution where we propose a constrained formulation of the data gathering and anomalies detection problem. We reformulate the textit{a prior} knowledge about the target data as hard convex constraints. Thus, the involved parameters into the developed algorithm become easy to adjust since they are related to some physical properties of the treated data. Both MC based approaches are tested on real datasets and demonstrate good capabilities in terms of data reconstruction quality and anomaly detection performance. Finally, we propose in the last contribution a position based compressive data gathering scheme where nodes cooperate to compute and transmit only the relevant positions of their sensory sparse representation. This technique provide an efficient tool to deal with the noisy nature of WSN environment as well as detecting spikes in the sensory data. Furthermore, we validate the efficiency of our solution by a theoretical analysis and corroborate it by a simulation evaluation
46
Bougiouklis, Theodoros C. "Traffic management algorithms in wireless sensor networks." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Sep%5FBougiouklis.pdf.
Full textAbstract:
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 2006.Thesis Advisor(s): Weillian Su. "September 2006." Includes bibliographical references (p. 79-80). Also available in print.
47
HSUEH, YI-FAN, and 薛易帆. "In-network Data Cleaning for Wireless Sensor Networks." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/11066207051188974367.
Full textAbstract:
碩士國立臺灣科技大學
電子工程系
96
Data cleaning is an important issue for wireless sensor networks, since wireless sensor networks operate in harsh and unreliable environments. In this research, we investigate an in-network cooperative data cleaning scheme for spatial correlated outliers in wireless sensor networks. High degree of spatial correlation in sensor data is used to infer missing value or correct value. First, we use Markov random field to model data dependency in wireless sensor networks, and use different similarity functions to design decision rules for choice of neighbors in the Markov random field. Then, belief propagation algorithm is proposed to compute and infer fault network data based on maximum a posteriori probability (MAP). To verify the performance of the proposed faulty data cleaning scheme, we run intensive computer simulations. The results of simulations show that the proposed data cleaning scheme can achieve high accuracy if the appropriate decision rule is chosen to determine neighbors in Markov random field model.
48
Liang, Wei-Kang, and 梁維剛. "Data dissemination in wireless sensor networks." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/80233400898817537611.
Full textAbstract:
碩士國立臺灣科技大學
電子工程系
104
Data collection is an important issue in wireless sensor networks. A mobile sink can balance network load; however, mobile sinks introduce challenges related to uncertain movement direction and speed. In this paper, we propose the data collection that takes advantage of a virtual backbone based on a connected dominating set and a rendezvous tree. In the proposed method, sensor nodes work independently to construct a path to the mobile sink without expensive GPS devices. Simulation results show that our algorithm can significantly reduce control packets, decrease data delivery delay, and increase network lifetime over state-of-the-art methods.
49
Sahu, Kunal Kumar. "Data aggregation in wireless sensor networks /." 2008. http://proquest.umi.com/pqdweb?did=1605158561&sid=3&Fmt=2&clientId=10361&RQT=309&VName=PQD.
Full text
50
Chang, Chih-Yen, and 張智彥. "Hybrid In-Network Data Aggregation Method in Wireless Sensor Networks." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/04535649979557431945.
Full textAbstract:
碩士國立臺灣科技大學
資訊工程系
97
Many researches aim on issues of in-network data aggregation methods, but hybrid methods, comparing to traditional ones, have advantage on performance and accuracy of data queries. Since many wireless sensor networks are allocated on hostile environments, communication failure rate between sensor nodes become not negligible in these cases. The recently proposed Tributaries-Deltas method compensates this problem by dynamically adjust the topology of data aggregation according to communication failure rate. This hybrid method successfully increases the accuracy of query results but keeping the required communication cost minimum. However, Tributaries¬Deltas method still has its problems. First, it can not distinguish between communication error and approximation error from the percentage contributing. Second, the conversion function it used could decrease the accuracy of the final results. Thus, we propose a new method that could check the communi¬cation error and the approximation error individually by the 2-layer checking at each mote. In our approach, the updating frequency can be changed by the querier, and a table is used to accumulate every epoch’s counting value at each mote. The results of experiments show that the proposed method could downgrade to synopsis diffusion method under high loss ratio environment. The other experiment results about the regional communication loss ratio showed that the approach change to synopsis diffusion when the sensor nodes near the base station got higher loss ratio. Under other conditions, our method could resist the bad environment caused by the communication error by adjusting the topology dynamically. From the experiment results, we conclude that our method could increase the accuracy of the result compared to Tributaries-Deltas and update the topology according to the network conditions.