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Li, JiakaiAI-WSN: Adaptive and Intelligent Wireless Sensor Networks
Doctor of Philosophy in Engineering, University of Toledo, 2012, College of Engineering

This dissertation research proposes embedding artificial neural networks into wireless sensor networks in parallel and distributed processing framework to implant intelligence for in-network processing, wireless protocol or application support, and infusion of adaptation capabilities. The goal is to develop in-network "intelligent computation" and "adaptation" capability for wireless sensor networks to improve their functionality, utility and survival aspects. The characteristics of wireless sensor networks bring many challenges, such as the ultra large number of sensor nodes, complex dynamics of network operation, changing topology structure, and the most importantly, the limited resources including power, computation, storage, and communication capability. All these require the applications and protocols running on wireless sensor network to be not only energy-efficient, scalable and robust, but also "adapt" to changing environment or context, and application scope and focus among others, and demonstrate intelligent behavior. The expectation from the research endeavor is to introduce computational intelligence capability for the wireless sensor networks to become adaptive to changes within a variety of operational contexts and to exhibit intelligent behavior.

The proposed novel approach entails embedding a wireless sensor network with an artificial neural network algorithm while preserving the parallelism and distributed nature of computations associated with the neural network algorithm. The procedure of embedding an artificial neural network, which may be configured for a problem either at wireless protocol or application levels, into the wireless sensor network hardware platform, which is a parallel and distributed processing system that is composed of a network of motes, is defined. This procedure is demonstrated for a case study with a Hopfield neural network and a minimum weakly connected dominating set problem as the model of wireless sensor network backbone or infrastructure. Issues and challenges pertaining to scalability, solution quality, and computational complexity for time and message are addressed through a comprehensive simulation study. Simulation study is performed using the TOSSIM environment for wireless sensor networks with mote counts up to 1000.

A comparative performance evaluation is performed. Solution quality, time and message complexity results for other centralized and distributed algorithms for connected dominating set construction as reported in the literature are used. Additionally, in-house simulation of non-distributed version of the proposed model is implemented to serve as a comparison benchmark and link to the studies in the literature. It is determined through the simulation study that the most critical factors that affect both the time complexity and the message complexity are the network size and time interval. The normalized computation time increases somewhat linearly for the most part for increases in the mote count the exception of the time interval value of 0.1 sec. The message complexity also increases with the increase in the mote count. The message complexity is not sensitive to the radio range but very sensitive to the time interval. All other parameters kept constant, the message complexity decreases with the increase in the time interval value on a consistent basis for all mote counts simulated. For smaller values of time interval, the network is more active due to motes waking up and exchanging messages more frequently, which leads to increased message complexity. The solution quality as measured by the size of the weakly connected dominating set by the proposed model is competitive with the performance exhibited by other algorithms reported in literature given all the adverse effects of computation being realized on a wireless sensor network platform. In light of the fact that there is significant opportunity to improve the entire wireless protocol stack for drastically reducing the time and space complexities through more efficient MAC, time synchronization and routing protocols, there is a strong prospect for the proposed architecture to scale up to tens of thousands of motes.

Committee:

Gursel Serpen (Committee Chair); Junghwan Kim (Committee Member); Mohsin Jamali (Committee Member); Jackson Carvalho (Committee Member); Eddie Chou (Committee Member)

Subjects:

Computer Science; Electrical Engineering

Keywords:

artificial neural network; wireless sensor network; parallel and distributed processing; weakly connected dominating set; sensor network infrastructure; Hopfield network; connected dominating set

Zeng, WenjieTopics in Energy Efficiency of Low-Power Wireless Sensor Networks
Doctor of Philosophy, The Ohio State University, 2012, Computer Science and Engineering

The growth of Wireless Sensor Network (WSN) technologies have spawned promising applications such as military surveillance and medical monitoring. However, due to the limited power resource, energy efficient networking has always remained a major challenge in making large scale WSN deployments viable.

The difficulty in achieving energy efficient networking depends heavily on the amount of network traffic. In this dissertation, we present techniques centering the Medium Access Control (MAC) and routing layers to enhance energy efficiency across a wide range of traffic: from when traffic is ultra-low and interference-free communication can be safely assumed, to when traffic becomes non-trivial and the explicit consideration of interference becomes necessary, and to finally override our mind set on interference by exploiting interference rather than avoiding it.

We first empirically investigate the efficiency of different classes of low-power scheduling protocols under different traffic situations. Existing knowledge regarding low-power MAC scheduling across different traffics is fragmented. To unify, we categorize a wide range of low-power MAC protocols according to the centricity and synchrony of their scheduling and group them into four scheduling classes. We extensively evaluate representative MAC protocols from each class under a wide range of traffic, showing that our implementation almost always outperforms those from the other classes.

A key observation from our empirical study above is that certain classes of MAC protocols can approximate interfere-free scheduling when traffic is low. From this observation, we developed two protocols that optimize the energy efficiency of convergecast via joint MAC and routing control. When traffic is ultra-low and interference-free scheduling can be approximated regardless of routing, we present a distributed and self-stabilizing protocol that minimizes power consumption. When traffic is not ultra-low but there exists some routing tree in which interference-free scheduling can be effectively approximated, we prove that the optimization problem is a linear one and present a centralized solution.

In cases where interference is no longer negligible and warrants explicit consideration, we revisit efficiency optimization by explicitly modeling interference using an Signal to Interference plus Noise Ratio (SINR) model. We solution consists of two steps: first, given a set of minimum link rate constraints, our technique optimizes the MAC layer by simultaneously controlling transmission scheduling and reception scheduling in order to minimize power consumption; secondly, we propose an routing metric that takes into account both transmission and reception energy expense.

In our last piece of work, we transition from managing and avoiding interference to actively exploiting interference. A common pattern in sensor network applications is the collection of up-to-date neighborhood metrics to perform local or distributed decision making. We may define this pattern in terms of a local state predicate over the sensor values or other local variables at each neighboring node. We present two primitives that exploit simultaneous communications to enable a polling node to calculate the number (or set) of its neighbors where some state predicate of interest holds.

Committee:

Anish Arora (Advisor); Ness Shroff (Committee Member); Ten Lai (Committee Member); Caroline Clark (Committee Member)

Subjects:

Computer Science

Keywords:

wireless sensor network; energy efficiency; MAC; scheduling; routing; SINR;

Rettig, Andrew J.An Open Geospatial Consortium Standards-based Arctic Climatology Sensor Network Prototype
MA, University of Cincinnati, 2010, Arts and Sciences: Geography
We have constructed a prototype Open Geospatial Consortium (OGC) standards-based Arctic Climatology Sensor Network Prototype (ACSNP) in response to recent developments in sensor technology and Internet Protocol Suite (TCP/IP) wireless communications in Barrow, Alaska for the National Science Foundation (NSF). The OGC standards enable increased, interoperability, scalability, and extensibility for geospatial information at a reduced cost. Our approach for the prototype is to integrate established technologies to create near-real-time geographic information networks (GINs). We linked a variety of meteorological and image sensors to wide area wireless networks in Barrow, Alaska. The network is a TCP/IP-based 700 Mhz WipLL network consisting of a 16 kilometer diameter local cloud as well as Iridium Open Port Units, which allow for global connectivity, at other remote research stations and on ice breakers. The Department of Energy (DOE) building in Barrow is the location of two automatically populated mirrored File Transfer Protocol (FTP) servers running Microsoft Server 2003 within a virtualized environment. High availability for the GIN is met through the use of virtualization as well as redundant power supplies and hardware-based security. The data are automatically harvested from the remote site over redundant 2XT-1 satellite links to the central data center in Cincinnati, Ohio where it is formatted to comply with the OGC database initiatives to create an OGC-compliant geodatabase within Microsoft SQL Server 2008. This cyberinfrastructure is remotely monitored 24X7 tracking network components and mission critical applications providing notification of potential capacity, connection and performance problems. The final web publication is the result of a three part system; geodatabases, web services and web applications. A data harvester is used for automating data retrieval and distribution into a geodatabase. The harvester allows for centralized control and monitoring of transfers through a browser interface and provides a comprehensive built-in scheduler and produces complete reports. A function of the database is the conversion of raw noncompliant sensor data into the standardized OGC geodatabase. For web services we use ESRI’s ArcGIS Server technology for retrieval and publication utilizing ESRI’s compliance with OGC web services. These web services may then be embedded within clients, such as ESRI’s ArcGIS Desktop and Google Earth for analysis, and web applications. The Arctic Climatology Sensor Network Prototype is accessible at OpenSensorMap.com.

Committee:

Richard Beck, PhD (Committee Chair); Robert Browning South, PhD (Committee Member); Hongxing Liu, PhD (Committee Member)

Subjects:

Geotechnology

Keywords:

Spatial Data Infrastructure;Geographic Information Network;Sensor Network;Open Geospatial Consortium;Climatology;Arctic

CHENG, YISecurity Mechanisms for Mobile Ad Hoc and Wireless Sensor Networks
PhD, University of Cincinnati, 2008, Engineering : Computer Science and Engineering

Wireless Ad Hoc Networks have emerged as an advanced networking paradigm based on collaborative efforts among multiple self-organized wireless communication devices. Without the requirement of a fixed infrastructure support, wireless ad hoc networks can be quickly deployed anywhere at any time when needed. The decentralized nature, minimal configuration and quick deployment of wireless ad hoc networks make them suitable for various applications, from disaster rescue, target tracking to military conflicts. Wireless ad hoc networks can be further categorized into mobile ad hoc networks (MANETs), wireless sensor networks (WSNs), and wireless mesh networks (WMNs) depending on their applications.

Security is a big challenge in wireless ad hoc networks due to the lack of any infrastructure support, dynamic network topology, shared radio medium, and resource-constrained wireless users. Most existing security mechanisms applied for the Internet or traditional wireless networks are neither applicable nor suitable for wireless ad hoc network environments. In MANETs, routing security is an extremely important issue, as the majority of the standard routing protocols assume non-hostile environments. Once deployed in a hostile environment and working in an unattended mode, existing routing protocols are vulnerable to various attacks. To address these concerns, we propose an anonymous secure routing protocol for MANETs in this dissertation, which can be incorporated with existing routing protocols and achieve enhanced routing security with minimum additional overheads.

In WSNs, key distribution and management is the core issue of any security approaches. Due to extremely resource-constrained sensor nodes and lack of any infrastructure support, traditional public-key based key distribution and management mechanisms are commonly considered as too expensive to be employed in WSNs. In this dissertation, we propose two efficient pairwise key pre-distribution and management mechanisms for both distributed and hierarchical large-scale WSNs, which enable establishing secure links between any two sensor nodes located within their communication range. As we know, sensing and communication are two fundamental characteristics of WSNs, and they cannot be addressed separately. Existing work on sensing coverage mainly focus on how to use the minimum number of sensors to achieve a required coverage, while security constraints are not sufficiently addressed. We propose an effective key distribution approach for randomly deployed WSNs, based on random graph theory and a realistic random key pre-distribution mechanism, in order to achieve both robust sensing coverage and secure connectivity simultaneously in a hostile deployment environment.

Committee:

Dharma Agrawal (Committee Chair); Jerome Paul (Committee Member); Wen-Ben Jone (Committee Member); Chia-Yung Han (Committee Member); Ernest Hall (Committee Member)

Subjects:

Communication; Computer Science

Keywords:

Wireless Ad Hoc Network; Mobile Ad Hoc Network (MANET); Wireless Sensor Network (WSN); Routing; Security; Cryptography; Key Management; Distributed Wireless Network; Hierarchical Wireless Network; Sensing Coverage; Secured Connectivity

JAIN, VIVEKON-DEMAND MEDIUM ACCESS IN HETEROGENEOUS MULTIHOP WIRELESS NETWORKS
PhD, University of Cincinnati, 2007, Engineering : Computer Science and Engineering
Recent years have witnessed an extensive proliferation of wireless technology in every domain of day-to-day life. Examples include mobile phones, broadband communication, wireless LAN, wireless enabled PDAs, cordless phones, garage-door openers and the list continues. Advancements in radio technology, antenna technology, low power computational digital signal processing (DSP) and micro-electro-mechanical systems (MEMS) are instrumental in reducing the size and cost of wireless devices. A wireless network consists of wireless devices forming an infrastructure-based or a peer-to-peer network. A network can be a single-hop or multihop network. Single-hop networks are already in existence and have been substantially investigated. This dissertation thus focuses on multihop wrireless networks, where the intermediate wireless devices also act as routers. Depending on their functionality, multihop wireless networks can be categorized into ad hoc, mesh and sensor networks. A mobile ad hoc network (MANET) aims at provding a mobile network with connectivity similar to a wired network without the need for any infrastructure support. A wireless mesh network (WMN) typically extends the infrastructure based single hop wireless network and has become a new paradigm for providing last mile broadband access. A wireless sensor network (WSN) is similar to an ad hoc network, providing a cheap alternative to monitoring applications. Each of these multihop wireless networks has their own set of challenges with respect to operation and implementation. The first part of this dissertation focuses on developing on-demand medium access control (MAC) protocols for multiple beam smart antennas (MBSAs) in ad hoc and mesh environments. MBSA has the unique capability of simultaneously initiating packet transmissions or receptions in multiple beams. Thus, compared to traditional omnidirectional antennas, MBSA can better utilize the spatial bandwidth, thereby increasing the capacity of wireless networks. We have performed both simulation and analytical studies to evaluate the proposed protocols for MBSA in ad hoc environments. To the best of our knowledge, this is the first attempt to analyze and develop on-demand protocols for multiple beam smart antennas. We have also proposed a cost-effective mesh network architecture employing heterogeneous antenna technologies and hybrid MAC protocol. The second part of this dissertation focuses on designing energy-efficient and reliable medium access mechanisms for wireless sensor networks. Sensor motes are battery-operated, hence protocols designed for them have to be innately energy-efficient. Also, depending on the application, reliability and latency might be important parameters. Taking into account all these design considerations, we have proposed dual-radio architecture. A low-energy wakeup radio is used to transmit and receive wakeup tones, while another transceiver is used for data communication. We have demonstrated the superior performance of our protocol using extensive simulation and analytical studies. We have also proposed a wireless sensor network testbed for quantifying reliability of wireless channels. The setup can be used to quantify reliability of wireless channels in terms of packet error rate, received signal strength and overall latency of the system. On the basis of our studies, we have provided deployment guidelines and medium access strategies for wireless sensor networks.

Committee:

Dr. Dharma Agrawal (Advisor)

Subjects:

Computer Science

Keywords:

Ad hoc Network; Concurrent Packet Reception; Deafness; Differentiated Service Classes; Medium Access Control; Mesh Network; Multihop Wireless Network; Multiple Beam Smart Antenna; Sensor Network

Desai, Pratikkumar U.Localization and Surveillance using Wireless Sensor Network and Pan/Tilt Camera
Master of Science in Engineering (MSEgr), Wright State University, 2009, Electrical Engineering

The ever growing challenges in hostile environments, health care and warzone require accurate indoor localization and surveillance. The de facto localization technique using GPS has poor indoor performance due to the complexity of the indoor environment. Other Radio frequency based indoor localization techniques are unable of accurate localization due to multipath fading.

In this thesis, a system consisting of Cricket wireless sensor motes, a camera and a Pan/Tilt gimbal is proposed to solve the indoor localization and surveillance problems. The system is easy to deploy, is cost effective and gives accurate results. The Crickets motes use the Time Difference of Arrival (TDoA) between the RF and the ultrasound signals to estimate the distance of the object. Multilateration is used to calculate the position of the object in the reference beacon coordinate system. This position is then transformed to the object coordinate system to calculate the pan and tilt angles of the gimbal which are then used to direct the camera to the object. The programming language JAVA was used to develop a GUI program to interface the gimbal, the camera and the Cricket motes.

The localization and tracking of the object was successfully carried out in the laboratory. The accuracy of the system was tested using a laser pointer mounted on top of the camera and was shown that the system tracked the object with negligible error.

Committee:

Kuldip Rattan, Ph. D. (Advisor); Xiaodong Zhang, Ph. D. (Committee Member); Devert Wicker, Ph. D. (Committee Member)

Subjects:

Electrical Engineering

Keywords:

wireless sensor network; localization; pan/tilt gimbal; surveillance

Martinez, Adam P.A Geometric Tiling Algorithm for Approximating Minimal Covering Sets
Master of Science, University of Akron, 2011, Applied Mathematics
The cover generation problem is relevant to the problem of creating large-scale wire- less sensor networks. Wireless sensor networks have short-ranged sensor nodes that may not be capable of transmitting to base station. Quickly and efficiently placing relay nodes allows the sensors to save on battery power and transmit information back to the base station via the relay nodes. Placing a minimal cover of relays is at least an NP-hard problem. We present a geometric tiling algorithm to construct an approximation to a minimal covering set in O(n) time. The algorithm fills the target region with a triangular grid of relays and then culls unnecessary points from the grid. A brief analysis of the algorithm is presented and a comparison to another cover-generation algorithm is performed.

Committee:

Timothy Norfolk, Dr. (Advisor); Curtis Clemons, Dr. (Committee Member); Kathy Liszka, Dr. (Committee Member)

Keywords:

wireless sensor; network; geometric tiling

Ash, Joshua N.On singular estimation problems in sensor localization systems
Doctor of Philosophy, The Ohio State University, 2007, Electrical Engineering

Distributed sensor networks are growing in popularity for a large number of sensing applications ranging from environmental monitoring to military target classification and tracking. However, knowledge of the individual sensor positions is a prerequisite to obtaining meaningful information from measurements made by the sensors. With the scale of sensor networks rapidly increasing due to advances in communications and MEMS technology, an automatic localization service based on inter-sensor measurements is becoming an essential element in modern networks. This dissertation studies fundamental aspects of localization performance while deriving general results for singular estimation problems.

Because inter-sensor measurements, such as distances or angles-of-arrival (AOA), are invariant to absolute positioning of the sensor scene, localizing sensors with an absolute reference, e.g., latitude and longitude, is inherently a singular estimation problem suffering from non-identifiability of the absolute location parameters. This results in a corresponding singular Fisher information matrix.

We consider means of regularizing the absolute localization problem and devise novel performance characterizations by showing that the location parameters have a natural decomposition into relative configuration and centroid transformation components based on the singularity of the problem. A linear representation of the transformation manifold, which includes representations of rotation, translation, and scaling, is used for decomposition of general localization error covariance matrices. The unified statistical framework presented – which naturally generalizes to non-localization problems – allows us to quantify and bound performance in the relative and transformation domains. These tools facilitate analysis of relative-only algorithms while enabling new algorithm development to finely tune performance in each subdomain. The analysis is applied to a novel closed-form AOA-based localization algorithm presented in the dissertation.

Finally, we consider anchor nodes, with a priori known positions, as a specific form of regularization and address optimal anchor selection and placement strategies for minimum mean-square localization error. We present a novel sensor placement heuristic based on minimizing principal angles between the anchor-induced constraint subspace and the non-identifiable transformation subspace. This work provides analytical justification for the frequent, but empirical, observation that perimeter-placement of anchors is desirable.

Committee:

Randolph Moses (Advisor)

Keywords:

Sensor network localization; Location estimation; Singular estimation; Singular Fisher information; Principal angles; Subspace methods; Anchor nodes

Jeong, Dong HwaDISTRIBUTED WIRELESS SENSOR NETWORK SYSTEMS: THEORETICAL FRAMEWORK, ALGORITHMS, AND APPLICATIONS
Doctor of Philosophy, Case Western Reserve University, 2015, EMC - Mechanical Engineering
This dissertation presents a theoretical framework and algorithms for distributed wireless sensor networks and their physical implementations on tangible geometric games (TAG-Games) to assess cognitive and motor skills automatically using sensor integrated geometric blocks (SIG-Blocks) with an interactive graphical user interface. To allow for a variety of possible game designs, single and multiple blocks were used to form diff erent geometrical con figurations. To resolve communication issues between the blocks as well as reliability issues with sensing, the following distributed wireless sensor network algorithms were developed: 1) self-synchronization technique in a local network, 2) a hybrid wireless network, 3) an assembly detection algorithm, and 4) a motion sensing algorithm. The theoretical framework of this paper is that distributed wireless sensor network is fault tolerant, scalable, and a dynamic solution to complex multi-agent systems. To evaluate the validity of the TAG-Games with the developed algorithms and proposed theoretical framework, 86 participants were recruited to the human subject evaluation aging from 18 to 30. The results con firmed that the TAG-Games is suitable as an automatic assessment tool. The developed algorithms and theoretical framework are applied to three extended applications, including swarm robots, wearable sensors, and origami robots. First, two swarm robotic platforms were developed and the wireless algorithms were implemented. One of them is a group of mobile robots with corner reflectors to localize using directional received signal strength. The other one is the InchBots, a cubic inch-sized omnidirectional swarm robotic platform with a stackable hardware feature for customization. The robotic swarm aims to achieve a global goal by using a large number of robots, each with limited capabilities. In this application, the hybrid wireless network, assembly detection algorithm, and the self-synchronization algorithm were utilized and a geometry-based global shape formation algorithms were also implemented. The simulation results showed that the simple robotic agents can achieve global shape formation, i.e., line formation and radial dispersion, by using only received signal strength without centralized control. Second, wearable sensors were prototyped aiming to measure person-to-person interactions as well as biological and environmental data. Integration of the received signal strength from the proposed hybrid wireless network algorithm and motion detection algorithms were embedded in the system. Lastly, robots with a novel origami design were developed to achieve amphibious locomotion and articulated manipulation using the semi-soft origami structures. In this application, the data traffic resulting from real-time video streaming was controlled by distributing the hardware and internet protocol efficiently. The presented applications were then validated for the system efficiency, cost, reliability, and showed the great potential in the fi eld of robotics, clinical studies, and in education.

Committee:

Kiju Lee (Committee Chair); Roger Quinn (Committee Member); Frank Merat (Committee Member); M. Cenk Cavusoglu (Committee Member)

Subjects:

Engineering; Robotics

Keywords:

distributed wireless sensor network

Kundu, TitirExploring Capture Effect for Efficient Channel Assignment in Wireless Sensor Network
MS, University of Cincinnati, 2015, Engineering and Applied Science: Computer Science
Wireless sensor networks (WSN) is widely used to monitor remote areas, like battlefield, forest fire prone areas, etc. to monitor, collect data and make corrective action based on this information. WSN gained wide popularity for its flexibility and ability to collect data without or with minimal human interference. WSN consists of sensor nodes and one or multiple sink nodes or base stations (BSs). The sensor nodes sense and collect information and relay this data in a multi-hop fashion to the sink nodes. The sink nodes aggregated these data and communicate to a remote station, where it’s analyzed and appropriate decision made. In WSNs the most common way to collect information is through flooding or data aggregation. The sensor nodes transmit the sensed data to the coordinator (BS) in a multi-hop fashion. In such scenarios, one of the common problems is interference amongst the sensor nodes while relaying the data. For example, collision occurs when more than two sensor nodes try to send their information to a third node simultaneously. This, in turn, leads to interference and increased number of re-transmission in the network. End-to-end delay or network latency is also increased. In our work, we have studied a way to minimize this interference and increase the performance of the network. We have considered two important aspects in our work. The first aspect is the physical layer capture effect and second is improved channel assignment between the sensor nodes. There has been a lot of work done on the capture effect and it is well known that capture effect in the physical layer enhances the performance. We study the effects of capture to improve channel assignment. Analyzing our initial results, we created a base network with 3 channels and another large WSN with the capture effect and assigned probability between each link pair. Once these two networks are selected, we used Qualnet simulator to simulate and study the performance of both the networks. We started our problem with 20 nodes and extended it up to 100 nodes. Variation in the density of the networks gave us very interesting results. We introduce an innovative solution that increases the performance in dense WSNs by exploiting physical layer capture effect to efficiently assign channels and reduce interference. Algorithms have been implemented and results obtained are summarized in this thesis along with the scope for future work.

Committee:

Dharma Agrawal, D.Sc. (Committee Chair); Prabir Bhattacharya, Ph.D. (Committee Member); Chia Han, Ph.D. (Committee Member)

Subjects:

Computer Science

Keywords:

Wireless Sensor Network;Channel Assignment;Capture Effect;Improve Performance

Gao, ZhenningParallel and Distributed Implementation of A Multilayer Perceptron Neural Network on A Wireless Sensor Network
Master of Science, University of Toledo, Engineering (Computer Science)
This thesis presents a study on implementing the multilayer perceptron neural network on the wireless sensor network in a parallel and distributed way. We take advantage of the topological resemblance between the multilayer perceptron and wireless sensor network. A single neuron in the multilayer perceptron neural network is implemented on a wireless sensor node, and the connections between neurons are achieved by the wireless links between nodes. While the computation of the multilayer perceptron benefits from the massive parallelism and the fully distribution when the wireless sensor network is serving as the hardware platform, it is still unknown whether the delay and drop phenomena for message packets carrying neuron outputs would prohibit the multilayer perceptron from getting a decent performance. A simulation-based empirical study is conducted to assess the performance profile of the multilayer perceptron on a number of different problems. Simulation study is performed using a simulator which is developed in-house for the unique requirements of the study proposed herein. The simulator only simulates the major effects of wireless sensor network operation which influence the running of multilayer perceptron. A model for delay and drop in wireless sensor network is proposed for creating the simulator. The setting of the simulation is well defined. Back-Propagation with Momentum learning is employed as the learning algorithms for the neural network. A formula for the number of neurons in the hidden layer neuron is chosen by empirical study. The simulation is done under different network topology and condition of delay and drop for the wireless sensor network. Seven data sets, namely Iris, Wine, Ionosphere, Dermatology, Handwritten Numerical, Isolet and Gisette, with the attributes counts up to 5000 and instances counts up to 7797 are employed to profile the performance. The simulation results are compared with those from the literature and through the non-distributed multilayer perceptron. Comparative performance evaluation suggests that the performance of multilayer perceptron using wireless sensor network as the hardware platform is comparable with other machine learning algorithms and as good as the non-distributed multilayer perceptron. The time and message complexity have been analyzed and it shows the scalability of the proposed method is promising.

Committee:

Gursel Serpen (Advisor); Mohsin Jamali (Committee Member); Ezzatollah Salari (Committee Member)

Subjects:

Artificial Intelligence; Computer Science

Keywords:

Artificial Intelligence; Artificial Neural Network; Machine Learning; Multilayer Perceptron; Wireless Sensor Network; Parallel Computing; Distributed Computing

Lee, JungwooREAL-TIME MONITORING OF LANDSLIDE USING WIRELESS SENSOR NETWORK
Doctor of Philosophy, The Ohio State University, 2009, Civil Engineering
Damage caused by landslides exceeds $ 3 billion annually in the U.S and more than $ 10 billion each year worldwide, making losses attributed to landslides greater than any other natural disaster except hurricanes. Along with massive property loss, thousands people are killed and injured every year as the result of landslides. Potentially, much of this property damage and many of the injuries and deaths can be avoided with an operational landslide warning system. The goal of this research is to develop a wireless sensor network to predict the onset of landslides. The system will work by recording orientation changes from tiltmeters deployed on the surface of landslide prone slopes. Basic wired detection systems have been installed but, due to the high costs, monitoring systems can only cover a limited portion of a slope and requiring pre-existing knowledge of the most likely slide locations. Wireless landslide detection systems today have many problems limiting their practicality. Current limitations include subsurface sensor installation costs, high energy consumption and actual validation at the network level. In this research software having the capacity to interpret signals and generate failure alerts is being developed. To validate the above system, measured displacement data using wired extensometers from select sites are converted to tilt values and for the same sites, failure modes showing vector plots are generated using a numerical analysis program. These failure modes will be compared with various non critical movements. These comparisons related to surface movement patterns will provide essential characteristics for the stable landslide warning algorithm. For demonstration of this system, a slope with forty nodes consisting of eight columns and five rows is considered to be representative a typical hill slope. This demonstration shows how to implement the proposed algorithm based on a simple on and off sensor which will perform similarly to a tiltmeter. Only one time streaming of an (on) signal is needed when tilt reaches pre-set level, so battery power is only needed to send this information without waking and sending data periodically. Demonstrations show that the proposed algorithm can be implemented and successfully detect landslides using current sensor network technology.

Committee:

William Wolfe, PhD (Advisor); Fabian Tan, PhD (Committee Member); Tarunjit Butalia, PhD (Committee Member)

Subjects:

Civil Engineering

Keywords:

Landslide; Wireless Sensor Network; Real-Time monitoring; Surface movement patterns; Wireless data acquisition

Ranganathan, AravindDynamic Forests and Load Balancing for Data Gathering in Wireless Sensor Networks
PhD, University of Cincinnati, 2010, Engineering : Computer Science and Engineering

We consider the online data gathering problem in wireless sensor networks and focus on load balancing for maximizing the network lifetime. We model the network as a shortest-path DAG which assigns a set of parent nodes for each node. Routing in the DAG is defined by forwarding the data from each node to one of its parents. We show that static routing approaches perform poor load balancing and are also NP-hard for optimizing the network lifetime. Hence, we define the notion of optimal network lifetime and optimal load balancing and consider two different dynamic forests based routing approaches in the DAG – probabilistic routing, and state-based routing.

Our probabilistic routing approach associates a non-0/1 Markov probability distribution on the edges of the DAG for making the parent selection. Using flow theory and probability theory we propose an efficient algorithm for computing the Markov probability distribution. Based on our results we have developed our two probabilistic routing algorithms – PBF routing and its variant a-PBF routing. Our state-based routing approach, on the other hand, uses the current state of the network to make the parent selection decision. Each node maintains a routing table with an entry for each parent node and the entries are updated based on current network state. Using the residual energy of a node as a parameter we have developed two state-based routing algorithms – MPE routing, and WPE routing. Based on extensive simulations we show that our algorithms achieve greater network lifetime and perform better load balancing compared to our lower-bound and upper-bound benchmark algorithms as well as other existing algorithms.

Among our other contributions, we have developed a novel way of capturing the inherent topological imbalance in the network called the Red-White-Blue (RWB) Balance diagrams. Further, since our results are based on the DAG modeling rather than the WSN itself, they are also applicable to other networks.

Committee:

Kenneth Berman, PhD (Committee Chair); Fred Annexstein, PhD (Committee Member); Anca Ralescu, PhD (Committee Member); Dharma Agrawal, DSc (Committee Member); Ali Minai, PhD (Committee Member)

Subjects:

Computer Science

Keywords:

Wireless Sensor Network; Load Balancing; DAG;n etwork lifetime; data gather; routing

SHAH, PAYAL D.DISTRIBUTED HEBBIAN INFERENCE OF ENVIRONMENT STRUCTURE IN SELF-ORGANIZED SENSOR NETWORKS
MS, University of Cincinnati, 2007, Engineering : Electrical Engineering
Ad hoc wireless sensor networks are emerging as an important technology for applications such as environmental monitoring, battlefield surveillance and infrastructure security. Centralized processing in sensor networks works well for small-scale systems, but for large systems, it becomes time-intensive, inefficient, insecure and non-scalable. In contrast, in-field or in-network distributed processing results in faster detection of phenomena, faster query response, and a scalable, robust network. Since the computation and communication in distributed networks is local, the network becomes more energy efficient and the communication cost is also lower. While most research so far has focused on the network aspects of these systems (e.g., routing, scheduling, etc.), the capacity for scalable, in-field information processing is potentially their most important attribute. Networks that can infer the phenomenological structure of their environment can use this knowledge to improve both their sensing performance and their resource usage. These intelligent networks would require much less a priori design, and be truly autonomous. This thesis presents a distributed algorithm for inferring the global topological connectivity of an environment through a simple self-organization algorithm based on Hebbian learning. The application considers sensors distributed over an environment with a network of tracks. Vehicles of various types move on these tracks according to rules unknown to the sensor network. Each sensor node infers the local topology of the track network by comparing its observations with those from neighboring sensors, using a method similar to Hebbian learning in neural networks. The complete topology of the network emerges from the distributed fusion of these local views. The system’s performance is evaluated based on its similarity to the actual underlying network. Ongoing research focuses on using the inferred topology for intelligent scheduling of nodes to enhance network lifetime without loss of performance.

Committee:

Dr. Ali Minai (Advisor)

Keywords:

Self-Organization; Distributed Sensor Network; Hebbian Learning; Topology Inference

Abuaitah, Giovani RimonTrusted Querying over Wireless Sensor Networks and Network Security Visualization
Master of Science in Computer Engineering (MSCE), Wright State University, 2009, Computer Engineering

Wireless sensor networks (WSNs) as an emerging technology faces numerous challenges. Sensor nodes are usually resource constrained. Sensor nodes are also vulnerable to physical attacks or node compromises. Answering queries over data is one of the basic functionalities of WSNs. Both resource constraints and security issues make designing mechanisms for data aggregation particularly challenging. In this thesis, we first explore the various security techniques for data aggregation in WSNs then we design and demonstrate the feasibility of an innovative reputation-based framework rooted in rigorous statistical theory and belief theory to characterize the trustworthiness of individual nodes and data queries in WSNs.

Detecting security vulnerabilities is an imperative task. Visualization techniques have been developed over decades and are powerful when employed in the field of network security. In this thesis, we present a novel security visualization tool called “SecVizer”.

Committee:

Bin Wang, PhD (Advisor); Yong Pei, PhD (Committee Member); Thomas Wischgoll, PhD (Committee Member)

Subjects:

Computer Science

Keywords:

trusted querying; spatial and temporal correlated wireless sensor network; WSN security; node compromise; network security visualization; parallel coordinate plot; SecVizer

Abuaitah, Giovani RimonANOMALIES IN SENSOR NETWORK DEPLOYMENTS: ANALYSIS, MODELING, AND DETECTION
Doctor of Philosophy (PhD), Wright State University, 2013, Computer Science and Engineering PhD
A sensor network serves as a vital source for collecting raw sensory data. Sensor data are later processed, analyzed, visualized, and reasoned over with the help of several decision making tools. A decision making process can be disastrously misled by a small portion of anomalous sensor readings. Therefore, there has been a vast demand for mechanisms that identify and then eliminate such anomalies in order to ensure the quality, integrity, and/or trustworthiness of the raw sensory data before they can even be interpreted. Prior to identifying anomalies, it is essential to understand the various anomalous behaviors prevalent in a sensor network deployment. Therefore, we begin this work by providing a comprehensive study of anomalies that exist in a sensor network deployment, or are likely to exist in future deployments. After this thorough systematic analysis, we identify those anomalies that, in fact, hinder the quality and/or trustworthiness of the collected sensor data. One approach towards the reduction of the negative impact of misleading sensor readings is to perform off-line analysis after storing a large amount of sensor data into a centralized database. To this end, in this work, we propose an off-line abnormal node detection mechanism rooted in machine learning and data mining. Our proposed mechanism achieves high detection accuracy with low false positives. The major disadvantage of a centralized architecture is the tremendous amount of energy wasted while communicating the sensor readings. Therefore, we further propose an on-line distributed anomaly detection framework that is capable of accurately and rapidly identifying data-centric anomalies in-network, while at the same time maintaining a low energy profile. Unlike previous approaches, our proposed framework utilizes a very small amount of data memory through on-line extraction of few statistical features over the sensor data stream. In addition, previous detection mechanisms leverage sensor datasets obtained from an earlier deployment or use synthetic data to test their effectiveness. Our framework, on the other hand, has been entirely implemented in TinyOS as a prototype readily deployable into existing sensor networks, alongside other essential protocols such as sensor data collection protocols. An advantage of our system is the fact that it relies on supervised learning. Supervised machine learning algorithms usually achieve higher accuracy than their unsupervised counterparts given a highly representative common ground truth. Thus, in this work, we also design highly expressive anomaly models that may be leveraged to inject anomalous readings into existing sensor network deployments. In order to do so, we have developed a tool called SNMiner which enables us not only to inject anomalies into a network of sensors, but also to extract important statistical features and evaluate the accuracy of a number of supervised machine learning algorithms.

Committee:

Bin Wang, Ph.D. (Advisor); Yong Pei, Ph.D. (Committee Member); Keke Chen, Ph.D. (Committee Member); Shu Schiller, Ph.D. (Committee Member)

Subjects:

Computer Engineering; Computer Science

Keywords:

anomaly detection; online anomaly detection; anomaly analysis; anomaly modeling; SNMiner; ABANDON; POND; sensor network deployments; wireless sensor networks

Jun, Jung HyunAnalysis of Optimal Strategies to Minimize Message Delay in Mobile Opportunistic Sensor Networks
PhD, University of Cincinnati, 2011, Engineering and Applied Science: Computer Science and Engineering

Wireless sensor networks (WSNs) are autonomous and self-healing networks of small battery powered sensors. Besides sensing their physical environments, these sensors are capable of communicate wirelessly, store, and compute data locally. The small size and its capability attract academics as well as industry for real-time monitoring of an area for potential events like wild fire, intruders, and hazardous gas. Since multi-hop communications from sources to sink node were unavoidable in WSNs, it is hard to achieve a longer life time.

To reduce multi-hop communication, the idea of using mobile nodes as relay nodes which collect data and deliver it to sink, was introduced to WSNs. In addition to life time improvement, the mobile relay nodes can also keep wireless bandwidth capacity to a constant level while the node density is high. The mobile relay nodes moves independently and random from the perspective of WSNs. Mobile Opportunistic sensor Network (MOsN) specifically denotes overlays of the mobile opportunistic network on top of a static wireless sensor network where the time taken for relay nodes to deliver the data from static sensors to sink is completely opportunistic and unbounded.

However, many applications related to security, emergency, and bio-hazard cannot tolerate this unbounded message delay. So we begin by analyzing the average time taken for relay nodes to deliver the message to sink in MOsN by modeling the delivery of message as a randomly moving particle with certain biasness towards the sink. The result shows this delay is a function of the message bias level and distance d from the sink to origin of message. The sink as placed in the center of tilted grid with the radius of D and the message bias level α which varies [0, 1], the delay can vary from Ο(d) to Ο(D log d) to Ο(D² log d). Based on this result, we propose an heuristic algorithm which forward the data to other relay nodes if it has the bias level larger than a threshold 1/(2x+1), where x is distance of relay node carrying message to the sink.

Finally, we deduced that the lower average message delay can be achieved by a static sensor wait for a relay node with its bias level higher than some threshold for its message delivery. Before we delve into optimal message handover policy, the movement of relay nodes modeled as a directed random walk with biases in their mobility. This bias random mobility model well represents the network of multiple independent but not identically moving relay. The relationship between the message bias level and mobility bias level is derived from a help of the simulation results. The optimal message handover policy based on the observed mobility bias level is proposed for static sensors at different locations when the inter-arrival time of relay nodes to a given static sensor is close to a constant. We also propose an optimal relay node selection algorithm in the case of inter-arriving time of relay nodes are linearly increasing.

Committee:

Dharma Agrawal, DSc (Committee Chair); Prabir Bhattacharya, PhD (Committee Member); Kenneth Berman, PhD (Committee Member); Manish Kumar, PhD (Committee Member); George Purdy, PhD (Committee Member)

Subjects:

Computer Science

Keywords:

opportunistic network;mobile relay node;average message delay;optimal handover policy;wireless sensor network;grid topology

Rahman, A.B.M. MostafizurAssessment of Bridge Service Life Using Wireless Sensor Network
Master of Science in Engineering, Youngstown State University, 2012, Department of Civil/Environmental and Chemical Engineering

This paper describes a method for estimating remaining service life of a bridge based on real-time responses of the bridge. Real-time responses were recorded using wireless sensor network. With a significant percentage of nation's bridges being structurally deficient or functionally obsolete and with no quantitative method of health monitoring being used in general practice, it has become the necessity to develop a SHM method, which will provide a quantitative assessment of overall bridge health. This research focuses on estimating overall condition of the bridge analyzing dynamic response rather than focusing on individual damage types, their severity and locations.

SHM process in this research uses dynamic responses of a bridge subjected to service loads, collects the response through a system of wireless sensor network, simulates an ideal and practical bridge using finite element model, and then estimates the remaining service life of the bridge based on the modal correlation between the existing and an ideal bridge condition. Results indicate that the bridge under this study has lost approximately 47% of its approximately 50 years of service life in 30 years of service. It was also observed that only higher order modes are more sensitive to damage compared to lower ones.

With limited budget available for bridge maintenance and repair, this research can help bridge owners, policy makers, transportation planners or any related professionals or organizations in prioritizing and allocating budgets based on actual bridge condition.

Committee:

AKM Anwarul Islam, PhD (Advisor); Javed Alam, PhD (Committee Member); Frank Li, PhD (Committee Member)

Subjects:

Civil Engineering; Engineering

Keywords:

Bridge Service Life Assessment; Bridge Health; Wireless Sensor Network; SHM; Structural Health Monitoring

Wang, DeminWireless Sensor Networks: Deployment Alternatives and Analytical Modeling
PhD, University of Cincinnati, 2008, Engineering : Computer Science and Engineering

A wireless sensor network (WSN) is a collection of sensors which are equipped with wireless radios and deployed in a given network domain (i.e., an environmental monitoring region). Recently, a number of efforts, both from industry and academia have been made for the purpose of effectively deploying WSN for a variety of applications (e.g., forest fire, chemical contamination of water or soil). The power constraints of sensor devices pose many fundamental design issues in WSNs, such as coverage, connectivity and lifetime. For example, design of an environmental monitoring WSN needs to target maintaining a satisfactory sensing coverage and transmit the required sensor data (e.g., temperature) to the base station (BS) or sink node, with period ranging from months to years. However, multihop transmission makes the sensors close to the BS consume more energy than other far away nodes because of packets to be relayed to the BS. Once closeby nodes use up their energy, data from far away nodes can not be transmitted to the BS directly and the network performance is heavily affected.

In this dissertation, we study different deployment strategies for WSNs. We introduce the use of some redundant nodes so that the lifetime of WSNs could be prolonged. Nonuniform deployment of WSNs is also discussed. The main idea is to deploy more nodes close to the BS so as to balance the energy consumption among all sensors. Three kinds of deployment strategies (deterministic deployment, partially controlled deployment and distribution controlled deployment) are studied. We also provide a data collection protocol design to support the nonuniform deployment architecture. We also explore the future research directions related with WSN deployment strategies.

Committee:

Dharma Agrawal, DSc (Committee Chair); Kenneth Berman, PhD (Committee Member); Chia-Yung Han, PhD (Committee Member); Wen-Ben Jone, PhD (Committee Member); Mingming Lu, PhD (Committee Member)

Subjects:

Computer Science

Keywords:

Wireless Sensor Network; nonuniform deployment; lifetime

Fiske, Robert M.Implementation and Evaluation of a TDMA Based Protocol for Wireless Sensor Networks
Master of Science in Software Engineering, Cleveland State University, 2010, Fenn College of Engineering
When evaluating MAC layer network protocols for wireless sensor networks performing simulations of a protocol’s operation can provide great insight into the performance of the protocol. In order to prove that a protocol will work in a real setting and not just at the theoretical level, however, there is no substitute for evaluation with a physical implementation. This thesis discusses a physical implementation and evaluation of the Many-to-One-Sensor-to-Sink (MOSS) MAC layer protocol for sink based wireless sensor networks using the MAC Layer Architecture for TinyOS. MOSS is a Time Division Multiple Access (TDMA) based protocol first proposed in an earlier work. MOSS aims to utilize the strengths and alleviate the weaknesses of TDMA. In addition to discussing and evaluating the physical MOSS implementation, the process of developing MAC layer protocol implementations with MLA is also discussed.

Committee:

Chansu Yu, PhD (Committee Chair); Wenbing Zhao, PhD (Committee Member); Nigamanth Sridhar, PhD (Committee Member)

Subjects:

Computer Engineering; Engineering

Keywords:

TDMA; WSN; Wireless Sensor Network; MAC; MLA; Mac Layer Architecture; MOSS; Many-to-One-Sensor-to-Sink;

Bathula, ManoharA Sensor Network System for Monitoring Short-Term Construction Work Zones
Master of Science in Electrical Engineering, Cleveland State University, 2008, Fenn College of Engineering

Safety hazards encountered near construction work zones are high, both in number and in the kind. There is a need to monitor traffic in such construction zones in order to improve driver and vehicle safety.

In the past traffic monitoring systems were built with high cost equipment such as inductive plates, video cameras etc. These solutions are too cost-prohibitive and invasive to be used in the large. Wireless sensor networks provide an opportunity space that can be used to address this problem. This thesis specifically targets temporary or short-term construction work zones. We present the design and implementation of a sensor network system targeted at monitoring the flow of traffic through these temporary construction work zones. As opposed to long-term work zones which are common on highways, short-term or temporary work zones remain active for a few hours or a few days at most. As such, instrumenting temporary work zones with monitoring equipment similar to those used in long-term work zones is not practical. Yet, these temporary work zones present an important problem in terms of crashes occurring in and around them. The design for this sensornet-based system for monitoring traffic is (a) inexpensive, (b) rapidly deployable, (c) requires minimal maintenance and (d) non-invasive. In this thesis we present our experiences in building this system, and testing this system in live work zones in the Greater Cleveland area.

Committee:

Nigamanth Sridhar, PhD (Committee Chair); Yu Chansu, PhD (Committee Member); Zhao Wenbing, PhD (Committee Member); Saini Yang, PhD (Committee Member)

Subjects:

Educational Software; Electrical Engineering

Keywords:

Sensor network applications; tracking;transportation engineering;spatial multiplexing

DE, DEBRAJCase Studies in Low Power Motion Sensing
Master of Science, The Ohio State University, 2009, Computer Science and Engineering

Wireless Sensor Networks hold great promise as an enabling technology for a variety of applications. Considering for instance wireless networks of motion sensors, which have diverse application in defense, mobility related technologies, clinical studies etc. Performance metrices for such applications include probabilities of event detection, false alarm, classification and mis-classification, detection latency, and lifetime of sensor. In this thesis we address research issues associated with these metrics, in particular the aspects of accurate sensing and power management. Our research focuses on two case studies in motion sensing: presence detection and activity monitoring.

Presence detection is a primitive of applications of motion sensing such as room occupancy detection. Towards the goal of developing a reliable and long lived conference room occupancy sensing system, we use a Pyroelectric InfraRed (PIR) sensor enabled Trio mote. We develop an occupancy sensing algorithm that shows reliability with no observed false alarms. Power management is achieved through a number of features, including duty cycling and dynamic stabilization. Proper selection of sampling speed and duration enable fast and reliable event detection. The resulting duty cycling algorithm yields an achievable lifetime of 68 days. Based on our analysis we also propose a modification in hardware design for improved lifetime.

Activity monitoring is a primitive of applications of motion sensing such as tracking human activity level. Towards the goal of developing an energy efficient framework for reliable and accurate human activity level indexing, we use a coherent pulsed doppler radar sensor. We characterize two classes of human motion: uniform gait and milling. Reliability comes with a discrimination algorithm that distinguishes between the motions of zero, one or many people. The algorithm shows rare occurrences of false alarms. We formulated an index of human activity level that proportionally represents motion activity intensity. We propose a power management technique that adapts to activity intensity in order to save energy for sensing. Based on our research, we identify further improvements for more energy efficient, reliable and accurate activity indexing.

Committee:

Anish Arora (Advisor); Rajiv Ramnath (Committee Member)

Subjects:

Computer Science

Keywords:

sensor; network; signal; human; activity; radar; PIR

Patil, Sharada KrishnaUsable, lightweight and secure, architecture and programming interface for integration of Wireless Sensor Network to the Cloud
Master of Science, The Ohio State University, 2011, Computer Science and Engineering

Wireless sensor networks (WSN) have been gaining popularity in recent years because of their potential to enable innovative applications in various fields. These fields include industrial, social, and regulatory applications, to name a few. If we extend a traditional sensor network to the Internet, WSNs that are dispersed and networked together can collaborate to accomplish many tasks that cannot be accomplished with a few powerful sensors or computers on a smaller network. With the gaining popularity of cloud services due to the pay per use policy of computation and data storage resources and easing of the burden of maintaining the service, using the cloud to integrate a WSN to the Internet has become viable.

The primary goal of this research is to investigate how to facilitate secure communication between a WSN and a cloud and to provide a secure policy for users to access such a service. We propose and develop an architecture and programming interface, named as Intortus, to enable this exploration. Intortus lets software programmers develop and deploy applications on WSN quickly by relieving the programmer from understanding and using the cloud provider API to access its data store, and writing embedded C code for sensors. There are many challenges enabling such a service that provides end to end secure communication, design constraints due to limitations in the services of cloud providers to mention a few. We discuss the issues and approach taken to build such an architecture and interface. This thesis also describes the functionality Intortus provides and how it can be further extended.

Committee:

Rajiv Ramnath, PhD (Advisor); Jay Ramanathan, PhD (Advisor)

Subjects:

Computer Science

Keywords:

Wireless Sensor Network; Cloud; Integration

SHARMA, ANURAGEXPLOITING SPATIAL CORRELATION USING TREE BASED POLYNOMIAL REGRESSION IN A THREE DIMENSIONAL WIRELESS SENSOR NETWORK
MS, University of Cincinnati, 2007, Engineering : Computer Engineering
A Wireless Sensor Network (WSN) consists of a large number of sensor nodes dispersed over a chosen area for monitoring purposes. Information about an event can be captured by the surrounding sensor nodes. Observations from the sensor nodes which are in close proximity are highly correlated. This is called Spatial Correlation. In this thesis, we propose a scheme to exploit the spatial correlation of data in a three dimensional sensor network by using polynomial regression technique. The scheme involves creation of a binary tree in the network, such that the network has two types of nodes viz., Tree nodes and Sensing nodes. The sensing nodes sense the physical attribute and report their position coordinates (x, y, z) and the sensed value to the nearest tree node. The tree nodes, on the other hand, fit a polynomial function on the received values and transmit the coefficients of regression to the parent tree node. The process starts with the leaf tree nodes and stops at the root. At the end of the process, the root has the polynomial function (Attribute value as a function of space coordinates) for the entire sensor network. When the sink queries the root, instead of flooding the entire network, the root can use the polynomial function to compute the attribute value at any location within the boundary. This saves a lot of energy in the sensor network. Simulations have been performed for different tree heights and different sensor nodes density. Results presented in graphical form indicate that a tree with a depth of four provides accurate values, with minimum error. Concluding remarks and plans for future work have also been presented.

Committee:

Dr. Dharma Agrawal (Advisor)

Subjects:

Computer Science

Keywords:

three dimensional wireless sensor network; data aggregation; polynomial regression

Emelko, Glenn A.A New Algorithm for Efficient Software Implementation of Reed-Solomon Encoders for Wireless Sensor Networks
Doctor of Philosophy, Case Western Reserve University, 2009, EECS - Electrical Engineering
With the recent introduction and development of ad-hoc wireless sensor networks, and other miniature or low-power communications systems, high performance at a low cost is a key critical factor. Reliable data transmission from these wireless sensors is necessary, especially if the sensor end-points are transmit-only type devices. Error correction codes may be used to improve reliability of the transmission, in many instances improving the operating margin by 6dB or more (depending on the correcting power of the code). Presented is an algorithm for highly efficient, compact Reed-Solomon error correction encoder, realized entirely in software. This improved encoding algorithm takes between 31 and 62 CPU cycles on an 8-bit processor to encode each symbol, requires under 60 words of ROM and only a single RAM location. Able to encode data at over 50K symbols per second on a 4 MIPS processor, this algorithm is well suited for low cost wireless sensor applications.

Committee:

Francis Merat, PhD (Committee Chair); Wyatt Newman, PhD (Committee Member); H. Andy Podgurski, PhD (Committee Member); William Schultz, PhD (Committee Member); David Singer, PhD (Committee Member)

Subjects:

Communication; Computer Science; Electrical Engineering; Mathematics

Keywords:

Algorithm Wireless Sensor Network Reed Solomon Encoder Error Correction Software

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