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Articles 1 - 12 of 12
Full-Text Articles in Systems and Communications
Leveraging Depolarization To Increase The Link Reliability For Wireless Sensors Operating In Hyper-Rayleigh Environments, Jeff Frolik, Vit Sipal, David J. Edwards
Leveraging Depolarization To Increase The Link Reliability For Wireless Sensors Operating In Hyper-Rayleigh Environments, Jeff Frolik, Vit Sipal, David J. Edwards
Articles
Wireless communications within enclosed environments such as aircraft and vehicles have been shown to experience fading with statistics that are worse than Rayleigh. Motivated by low-cost, low-complexity systems (e.g., wireless sensors) that may be deployed in such environments, this work explores the benefits of polarization diversity using very large data sets collected over a small area and over the 5-6 GHz band. The results also demonstrate that antennas capable of capturing depolarized signal components can significantly mitigate the harshest of fading environments.
Impact Of Primary User Activity On The Performance Of Energy-Based Spectrum Sensing In Cognitive Radio Systems, Sara L. Macdonald
Impact Of Primary User Activity On The Performance Of Energy-Based Spectrum Sensing In Cognitive Radio Systems, Sara L. Macdonald
Electrical & Computer Engineering Theses & Dissertations
Increasing numbers of wireless devices and mobile data requirements have led to a spectrum shortage. However spectrum utilization percentages are often low due to the current static spectrum allocation process where primary users (PUs) are given exclusive use to spectrum. Several mechanisms to increase spectrum utilization have been proposed including opportunistic spectrum access (OSA). Cognitive Radio (CR) is an emerging concept in wireless communication systems that aims to enable OSA in licensed frequencies by secondary users (SUs). CR systems are expected to sense the spectrum in order to determine if the PU is transmitting. Therefore OSA performance relies on the …
On Reducing Communication Energy Using Cross-Sensor Coding Technique, Kien Nguyen, Thinh Nguyen, Sen-Ching Cheung
On Reducing Communication Energy Using Cross-Sensor Coding Technique, Kien Nguyen, Thinh Nguyen, Sen-Ching Cheung
Electrical and Computer Engineering Faculty Publications
This paper addresses the uneven communication energy problem in data gathering sensor networks where the nodes closer to the sink tend to consume more energy than those of the farther nodes. Consequently, the lifetime of a network is significantly shortened. We propose a cross-sensor coding technique using On-Off keying which exploits (a) the tradeoff between delay and energy consumption and (b) the network topology in order to alleviate the problem of unequal energy consumption. We formulate our coding problem as an integer linear programming problem and show how to construct a number of codes based on different criteria. We show …
Free Regions Of Sensor Nodes, Laxmi P. Gewali, Navin Rongatana, Henry Selvaraj, Jan B. Pedersen
Free Regions Of Sensor Nodes, Laxmi P. Gewali, Navin Rongatana, Henry Selvaraj, Jan B. Pedersen
Electrical & Computer Engineering Faculty Research
We introduce the notion of free region of a node in a sensor network. Intuitively, a free region of a node is the connected set of points R in its neighborhood such that the connectivity of the network remains the same when the node is moved to any point in R. We characterize several properties of free regions and develop an efficient algorithm for computing them. We capture free region in terms of related notions called in-free region and out-free region. We present an O(n2) algorithm for constructing the free region of a node, where n is the number of …
Distributed Cluster-Based Outlier Detection In Wireless Sensor Networks, Swetha Gali
Distributed Cluster-Based Outlier Detection In Wireless Sensor Networks, Swetha Gali
Electrical & Computer Engineering Theses & Dissertations
Wireless sensor networks find several potential applications in a variety of fields, such as environmental monitoring and control, battlefields, surveillance, smart buildings, human health monitoring, etc. These sensor networks consist of a large number of very tiny, inexpensive, and low power sensor nodes, which are deployed in a variety of harsh environments that may result in the sensor data getting corrupted. It is thus critical to detect and report these abnormal values in the sensor data, in order to have a better understanding of the monitored environment. Detection of the abnormal values is of special interest for the sensor network …
Energy-Efficient Querying Of Wireless Sensor Networks, Christopher R. Mann
Energy-Efficient Querying Of Wireless Sensor Networks, Christopher R. Mann
Theses and Dissertations
Due to the distributed nature of information collection in wireless sensor networks and the inherent limitations of the component devices, the ability to store, locate, and retrieve data and services with minimum energy expenditure is a critical network function. Additionally, effective search protocols must scale efficiently and consume a minimum of network energy and memory reserves. A novel search protocol, the Trajectory-based Selective Broadcast Query protocol, is proposed. An analytical model of the protocol is derived, and an optimization model is formulated. Based on the results of analysis and simulation, the protocol is shown to reduce the expected total network …
Fault Arrangements And Their Effect On The Performance Of Wireless Sensor Networks, Dwayne Sayone Blai
Fault Arrangements And Their Effect On The Performance Of Wireless Sensor Networks, Dwayne Sayone Blai
Electrical & Computer Engineering Theses & Dissertations
Wireless sensor networks face many reliability challenges. The networks are deployed in open, hostile environments, making them easily susceptible to network failure. As a result, there are countless faults that can occur in sensor networks, from component failure to outside attacks. Outside attacks take place when an adversary gains control over a node or set of nodes in the network. Outside attackers can destroy a network in numerous ways such as random attacks, clustering attacks, search-based attacks, etc. The method and strategy used in each of these attacks directly affects the network's reliability. Understanding how these adversaries are positioned is …
An Operational Model For Mobile Sensor Cloud Management, Indrajeet Kalyankar
An Operational Model For Mobile Sensor Cloud Management, Indrajeet Kalyankar
Electrical & Computer Engineering Theses & Dissertations
Mobile sensors provide a safe, cost effective method for gathering information in hazardous environments. When the hazardous environment is either unexplored, such as the surface of Mars, or unanticipated, such as the result of chemical contamination, it is desirable for a system to gather information with a minimal amount of outside control (localization, decision control, etc.) and prepositioned sensors. If one takes a look at the number of the sensors deployed on a scale, at the lower end is the sole, multipurpose sensor unit. The upper end deals with hordes of inexpensive, expendable sensors. In the middle, a cluster of …
Exploiting Semi-Directional Transceivers For Localization In Communication Systems, Andrew S. Crockford
Exploiting Semi-Directional Transceivers For Localization In Communication Systems, Andrew S. Crockford
Theses and Dissertations
Localization is the process of determining relative, as well as absolute, positions of communicating devices. Traditionally, the process is conducted using range or directional estimates. In contrast, this research uses weak information to form relatively tight bounds on possible locations of communicating devices. Under certain conditions, achieved location estimation results are strong. However, these results are highly sensitive to the operating conditions of the proposed networks. More significant results were obtained from specialized cases and that the application yields somewhat limited information for a general randomized network topology. Feasible localization results were found to be attainable but not necessarily practical …
Robust And Efficient Localization Techniques For Cellular And Wireless Sensor Networks, Haseebulla M. Khan
Robust And Efficient Localization Techniques For Cellular And Wireless Sensor Networks, Haseebulla M. Khan
Computer Science Theses & Dissertations
Localization in wireless networks refers to a collection of tasks that, collectively, determines the location of a mobile user, striving to hide the effects of mobility from the user and/or application. Localization has become an important issue and has drawn considerable attention, as many applications including E-911, cargo tracking, locating patients, location-sensitive billing, etc., require knowledge of the location of user/objects. It was realized, quite a while back, that extending emergency 911-like services (E-911) to continually growing mobile population is one of the extremely important localization applications. The bulk of the proposed solutions to emergency location management in wireless environments …
Mobility-Pattern Based Localization Update Algorithm For Mobile Wireless Sensor Networks, Mohammad Yacoub Al-Laho
Mobility-Pattern Based Localization Update Algorithm For Mobile Wireless Sensor Networks, Mohammad Yacoub Al-Laho
Electrical & Computer Engineering Theses & Dissertations
In mobile wireless sensor networks, sensors move in the monitored area at any direction and speed. Unlike many other networking hosts, sensor nodes do not have global addresses. They are often identified by using a location-based addressing scheme. Therefore, it is important to have the knowledge of the sensor location indicating where the data came from. In this thesis, three localization update algorithms were designed, Specifically, a sensor movement is divided into three states: Pause, Linear, and Random. Each state adopts different localization update algorithm. Since complex movement involves different mobility patterns, a state transition model is developed to …
Energy-Efficient Self-Organization Protocols For Sensor Networks, Qingwen Xu
Energy-Efficient Self-Organization Protocols For Sensor Networks, Qingwen Xu
Computer Science Theses & Dissertations
A Wireless Sensor Network (WSN, for short) consists of a large number of very small sensor devices deployed in an area of interest for gathering and delivery information. The fundamental goal of a WSN is to produce, over an extended period of time, global information from local data obtained by individual sensors. The WSN technology will have a significant impact on a wide array of applications on the efficiency of many civilian and military applications including combat field surveillance, intrusion detection, disaster management among many others. The basic management problem in the WSN is to balance the utility of the …