Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 45 for “"radio propagation"”.
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Radio propagation in fire environments.
Radio propagation in the presence of fire is known to be problematic to communications. In this thesis we use both experimental and theoretical approaches to examine and understand radio propagation in fire environments. Propagation is examined for three small scale fires with broadband equipment …
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Medium frequency radio propagation in urban settings
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.
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Fade durations in satellite-path mobile radio propagation
Fades on satellite to land mobile radio links are caused by several factors, the most important of which are multipath propagation and vegetative shadowing. Designers of vehicular satellite communications systems require information about the statistics of fade durations in order to overcome or …
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Radio Propagation Through Density Irregularities in the Auroral Ionosphere
<p>A radio wave propagating through a structured or turbulent ionosphere undergoes multiple effects, such as refraction, diffraction, etc., that distort the incident radio wave by inducing phase and amplitude fluctuations. These fluctuations are called<em> ionospheric</em><em> scintillation</em>. …
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Radio propagation analysis for improved UAV data muling of surfaced underwater sensor nodes
… respect to distance and height using a two-ray propagation model in conjunction with the individual radiation patterns of transmitting and receiving antennas. Signal quality over space is then be used to select best waypoints. Packet reception rate is related to the received signal strength …
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Investigating the use of ray tracing for signal-level radar simulation in space monitoring applications: a comparison of radio propagation models
… the Simplified General Perturbations #4 orbit propagation model, enabling the accurate modelling of targets and the dynamic orbital forces acting upon them. As a result, the software has aptly been named the Space Object Astrodynamics and Radar Simulator – or SOARS. SOARS was built upon the …
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The Effect of Digital Elevation Model Resolution on Wave Propagation Predictions at 24Ghz
… can be used to predicted Line-of-Sight (LOS) radio propagation. DEM resolution can affect the results of this prediction. This study examines the effect of DEM resolution on accuracy by comparing varied resolution terrain data for a portion of Blacksburg, Virginia using the prediction of …
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Fixed chain-based wireless sensor network for intelligent transportation systems
… level, there are some challenges related to radio propagation, energy constraints and the Media Access Control (MAC) protocol. This thesis develops a ground level radio propagation model for communication between road studs, and energy efficiency metrics to manage the resources to overcome …
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Improving the planning and deployment of wireless networks via the application of deep learning
… the development of advanced tools for radio propagation modeling and resource allocation in next-generation wireless networks. It introduces an enhanced empirical model that utilizes extracted path loss components to expedite outdoor path loss predictions. Additionally, it presents the …
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Secure OFDM System Design for Wireless Communications
… in people's daily life. The broadcast nature of radio propagation, however, causes wireless communications particularly vulnerable to malicious attacks, and leads to critical challenges in securing the wireless transmission. Motivated by the insufficiency of traditional approaches to secure …
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A Technique for Evaluating the Uncertainties in Path Loss Predictions Caused by Sparsely Sampled Terrain Data
Radio propagation models provide an estimate of the power loss in a communication link caused by the surface of the ground, atmospheric refraction, foliage, and other environmental factors. Many of the models rely on digital topographic databases to provide information about the terrain, and …
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Ionospheric Simulator (IonSim): Simulating Ionospheric conditions in a vacuum chamber
… This understanding improves prediction of radio propagation used for communication and GPS navigation. Various space-borne instruments, such as retarding potential analyzers (RPAs) and ion traps are routinely flown in low earth orbit (LEO) to provide data for seeding/improve ionospheric …
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Analysis and modelling of the impact of anomalous propagation on terrestrial microwave links in a subtropical region, based on long-term measurements. Statistical analysis of long-term meteorological and signal strength measurements in a subtropical region and investigation of the impact of anomalous refractivity profiles on radio propagation in terrestrial microwave wireless systems
Prevailing propagation phenomena in certain areas play a vital role in deciding terrestrial wireless systems performance. Vertical refractivity profile below 1 km is a critical parameter for designing reliable systems; noting that there is a shortage of upper-air data worldwide. Anomalous phenomena …
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Optimal transmitter placement in wireless mesh networks
… provide digital services to client devices via radio transmission. We consider the challenges of quickly and optimally designing a wireless mesh network. We focus on maximizing client coverage area by choice of access point locations, subject to constraints on network service, quantity and …
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Indoor Propagation Modeling at 2.4 GHz for IEEE 802.11 Networks
… challenges. It is difficult to predict the propagation of a radio frequency wave in an indoor environment. To assist in deploying the above systems, characterization of the indoor radio propagation channel is essential. The contributions of this work are two-folds. First, in order to build a …
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Collaborative Motion for Mobile Platforms
… as many agents as possible to avoid data loss. A radio propagation model is also presented to simulate communication in indoor and simulated environments, as well as estimated propagation for use in path planning. This framework will also allow the agent’s high level decision making to modify its …
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In defense of wireless carrier sense
… behavior in the two-sender case, based upon radio propagation theory and Shannon capacity. We argue from our model that common notions about carrier sense, such as the hidden and exposed terminal phenomena, are inherently misleading in the context of adaptive bitrate, casting in black and …
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Microwave multipath resolution in microcellular channels
The objective of this research is to compare radio channel impulse response measurements with site-specific radio wave propagation prediction techniques. A wide band spread spectrum measurement system was developed, and desirable measurement locations were selected on the Virginia Tech campus. …
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An Integrated voice-data transmission system for private mobile radio
Private mobile radio services have experienced for a number of years congestion of the available spectrum. Although the release of Band III has contributed significantly to alleviating the spectrum shortage, it will however, not be sufficient to accommodate the projected growth in private mobile …
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