Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 11 of 11
Full-Text Articles in Engineering
A General Framework For Analyzing, Characterizing, And Implementing Spectrally Modulated, Spectrally Encoded Signals, Marcus L. Roberts
A General Framework For Analyzing, Characterizing, And Implementing Spectrally Modulated, Spectrally Encoded Signals, Marcus L. Roberts
Theses and Dissertations
Fourth generation (4G) communications will support many capabilities while providing universal, high speed access. One potential enabler for these capabilities is software defined radio (SDR). When controlled by cognitive radio (CR) principles, the required waveform diversity is achieved via a synergistic union called CR-based SDR. Research is rapidly progressing in SDR hardware and software venues, but current CR-based SDR research lacks the theoretical foundation and analytic framework to permit efficient implementation. This limitation is addressed here by introducing a general framework for analyzing, characterizing, and implementing spectrally modulated, spectrally encoded (SMSE) signals within CR-based SDR architectures. Given orthogonal frequency division …
Evaluation Of The Effects Of Predicted Associativity On The Reliability And Performance Of Mobile Ad Hoc Networks, Esteban Francisco Sanchez
Evaluation Of The Effects Of Predicted Associativity On The Reliability And Performance Of Mobile Ad Hoc Networks, Esteban Francisco Sanchez
Theses and Dissertations
Routing in Mobile Ad Hoc Networks (MANETs) presents unique challenges not encountered in conventional networks. Predicted Associativity Routing (PAR) is a protocol designed to address reliability in MANETs. Using associativity information, PAR calculates the expected lifetime of neighboring links. Nodes use this expected lifetime, and their neighbor's connectivity to determine a residual lifetime. The routes are selected from those with the longest residual lifetimes. In this way, PAR attempts to improve the reliability of discovered routes. PAR is compared to AODV using a variety of reliability and performance metrics. Despite its focus on reliability, PAR does not provide more reliable …
Evaluation Of Energy Costs And Error Performance Of Range-Aware Anchor-Free Localization Algorithms For Wireless Sensor Networks, Gustav Julio Jordt
Evaluation Of Energy Costs And Error Performance Of Range-Aware Anchor-Free Localization Algorithms For Wireless Sensor Networks, Gustav Julio Jordt
Theses and Dissertations
This research examines energy and error tradeoffs in Anchor-Free Range-Aware Wireless Sensor Network (WSN) Localization algorithms. A concurrent and an incremental algorithm (Anchor Free Localization (AFL) and Map Growing) are examined under varying network sizes, densities, deployments, and range errors. Despite current expectations, even the most expensive configurations do not expend significant battery life (at most 0.4%), implying little energy can be conserved during localization. Due to refinement, AFL is twice as accurate, using 6 times the communication. For both, node degree affects communication most. As degree increases, Map Growing communication increases, while AFL transmissions drop. Nodes with more neighbors …
An Adaptable Energy-Efficient Medium Access Control Protocol For Wireless Sensor Networks, Justin T. Kautz
An Adaptable Energy-Efficient Medium Access Control Protocol For Wireless Sensor Networks, Justin T. Kautz
Theses and Dissertations
Wireless networks have become ubiquitous recently and therefore their usefulness has also become more extensive. Wireless sensor networks (WSN) detect environmental information with sensors in remote settings. One problem facing WSNs is the inability to resupply power to these energy-constrained devices due to their remoteness. Therefore to extend a WSN's effectiveness, the lifetime of the network must be increased by making them as energy efficient as possible. An energy efficient medium access control (MAC) can boost a WSN's lifetime. This research creates a MAC protocol called Adaptive sensor Medium Access Control (AMAC) which is based on Sensor Medium Access Control …
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 …
Supplementing An Ad-Hoc Wireless Network Routing Protocol With Radio Frequency Identification (Rfid) Tags, Leroy S. Willemsen
Supplementing An Ad-Hoc Wireless Network Routing Protocol With Radio Frequency Identification (Rfid) Tags, Leroy S. Willemsen
Theses and Dissertations
Wireless sensor networks (WSNs) have a broad and varied range of applications, yet all of these are limited by the resources available to the sensor nodes that make up the WSN. The most significant resource is energy. A WSN may be deployed to an inhospitable or unreachable area, leaving it with a non-replenishable power source. This research examines a way of reducing energy consumption by augmenting the nodes with radio frequency identification (RFID) tags that contain routing information. It was expected that RFID tags would reduce the network throughput, the ad hoc on-demand distance vector (AODV) routing traffic sent, and …
Evaluation And Analysis Of Node Localization Power Cost In Ad-Hoc Wireless Sensor Networks With Mobility, Brian A. Sessler
Evaluation And Analysis Of Node Localization Power Cost In Ad-Hoc Wireless Sensor Networks With Mobility, Brian A. Sessler
Theses and Dissertations
One of the key concerns with location-aware Ad-hoc Wireless Sensor Networks (AWSNs) is how sensor nodes determine their position. The inherent power limitations of an AWSN along with the requirement for long network lifetimes makes achieving fast and power-efficient localization vital. This research examines the cost (in terms of power) of network irregularities on communications and localization in an AWSN. The number of data bits transmitted and received are significantly affected by varying levels of mobility, node degree, and network shape. The concurrent localization approach, used by the APS-Euclidean algorithm, has significantly more accurate position estimates with a higher percentage …
Performance Analysis Of A Cooperative Search Algorithm For Multiple Unmanned Aerial Vehicles Under Limited Communication Conditions, Kevin M. Morris
Performance Analysis Of A Cooperative Search Algorithm For Multiple Unmanned Aerial Vehicles Under Limited Communication Conditions, Kevin M. Morris
Theses and Dissertations
This research investigates the impacts of realistic wireless communications upon a group of unmanned aerial vehicles (UAVs) utilizing a distributed search algorithm. The UAVs are used to survey an area for mobile targets and they require communication to cooperatively locate the targets. The mobile targets do not continually radiate energy, which exacerbates the search effort; a UAV could fly directly over a target and not detect it. A simulation of cooperative UAVs is implemented using the OPNET Modeler network simulation tool. The search performance of a group of UAVs is observed when communication range, data rate, and the number of …
Combining Quality Of Service And Topology Control In Directional Hybrid Wireless Networks, Michael C. Erwin
Combining Quality Of Service And Topology Control In Directional Hybrid Wireless Networks, Michael C. Erwin
Theses and Dissertations
Recent advancements in information and communications technology are changing the information environment in both quantitative and qualitative measures. The developments in directional wireless capabilities necessitate the ability to model these new capabilities, especially in dynamic environments typical of military combat operations. This thesis establishes a foundation for the definition and consideration of the unique network characteristics and requirements introduced by this novel instance of the Network Design Problem (NDP). Developed are a Mixed-Integer Linear Program (MILP) formulation and two heuristic strategies for solving the NDP. A third solution strategy using the MILP formulation with a degree-constrained Minimum Spanning Tree starting …
Free Roaming: A System For Ubiquitous Computing, Huanjin Liu
Free Roaming: A System For Ubiquitous Computing, Huanjin Liu
Theses Digitization Project
Based on the Umbilical Cord system, this project enriches the Ubiquitous Computing system with a Free Roaming system. This Free Roaming consists of a distributed authentication system, a data caching system and a communication system between them. It allows user to roam within this system and access his data everywhere. Together with the Umbilical Cord system, a Ubiquitous Computing system is functionally completed as a prototype, and is ready to be deployed into the Internet.
Analysis Of Relay-Based Cellular Systems, Ansuya Negi
Analysis Of Relay-Based Cellular Systems, Ansuya Negi
Dissertations and Theses
Relays can be used in cellular systems to increase coverage as well as reduce the total power consumed by mobiles in a cell. This latter benefit is particularly useful for mobiles operating on a depleted battery. The relay can be a mobile, a car or any other device with the appropriate communication capabilities. In thesis we analyze the impact of using relays under different situations. We first consider the problem of reducing total power consumed in the system by employing relays intelligently. We find that in a simulated, fully random, mobile cellular network for CDMA (Code Division Multiple Access), significant …