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 27 for “"LEO Satellite"”.
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Reduced-Order Atmospheric Density Modeling for LEO Satellite Orbital Reentry Prediction
… are vital to drag force estimation for satellite reentry prediction and conjunction assessment in today's increasingly cluttered Low Earth Orbit (LEO) environment. Current density models can be computationally expensive, and often contain large errors, which make density modeling a …
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Performance modeling and analysis of parallel processing and low earth orbit satellite communication systems
… system examined operates in a low earth orbit (LEO) satellite communications network environment. In this type of network, delay performance is affected by both queuing and propagation effects. The objectives of this research are to study the effects of queuing and propagation on the average …
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SIGNAL ANALYSIS AND RADIOHOLOGRAPHIC METHODS FOR AIRBORNE RADIO OCCULTATIONS
… now operational on several Low Earth Orbiting (LEO) satellite missions. Nevertheless, when observing localized transient events, such as tropical storms, current LEO satellite systems cannot provide sufficiently high temporal and spatial resolution soundings. An airborne RO (ARO) system has …
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QoS Provisioning for Multi-Class Traffic in Wireless Networks
… a predictive resource reservation scheme for LEO satellite networks that exploits the regularity of the movement patterns of mobile hosts in LEO satellite networks. We have developed the cellular network simulator (CNS) for evaluating call-level QoS provisioning schemes. QoS at the call-level …
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Miniaturized Antenna for Satellite Broadband Application
… antenna is a crucial component of a high-speed satellite internet system. High directivity, broadband characteristics, and circularly polarized radiations are essential for a user antenna to maintain a reliable connection with the overhead LEO satellite constellation. For commercialization and …
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A Systems Framework for Multi-Messenger Astronomy
… study regards using star tracker imagery from LEO satellite constellations to improve our knowledge of resident space objects Ð active satellites and debris. Traditionally, orbit determination relies on bespoke ground-based radar systems which are increasingly insufficient to meet the needs of …
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Prediction-enhanced Routing in Disruption-tolerant Satellite Networks
… Networking) routing in dynamic LEO satellite constellations based on the prediction of contacts. The solution is developed with a clear focus on the requirements imposed by the 'Ring Road' use case, mandating a concept for dynamic contact prediction and its integration into a …
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The Virginia Tech FlatSat: A platform for small satellite testing
The small satellite community understands that small satellite missions need to produce two models of the satellite. The flight model is the final model of the spacecraft, which will fly in the space environment. The other, an engineering model, also known as a ”Flat-Sat,” is a lower fidelity …
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GNSS-based Spacecraft Formation Flying Simulation and Ionospheric Remote Sensing Applications
The Global Navigation Satellite System (GNSS) is significantly advantageous to absolute and relative navigation for spacecraft formation flying. Ionospheric remote sensing, such as Total Electron Content (TEC) measurements or ionospheric irregularity studies are important potential Low Earth Orbit …
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Evaluating the Strategic Intent and Competitive Dynamics of China’s Satellite Communications Constellations
… of China’s two flagship low Earth orbit (LEO) satellite megaconstellation programs, Guowang and Qianfan, in the context of the rapidly evolving global satellite communication (Satcom) market. Against the backdrop of SpaceX’s Starlink dominance and intensifying geopolitical competition, …
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Capacity provisioning, failure recovery and throughput analysis for low earth orbit satellite constellations
… the capacity needed to build a restorable satellite network and design routing schemes to achieve high throughput. Specifically, the first part of this thesis considers the link capacity requirement for a LEO satellite constellation. We model the constellation as an N x N mesh-torus …
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Cost optimization and routing for satellite network constellations
Low-earth orbit (LEO) satellite communications systems have been under rapid development in the past few years as it is predicted that they will become part of the Next Generation Internet (NGI), a global heterogeneous network that provides ubiquitous access to every part of the world. …
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A Low Power Beacon for Transmitting Location Data via the Globalstar Satellite System
… on these conditions, and the Globalstar Satellite System was selected to use as the communication system for the beacon. The Globalstar Satellite System is a low earth orbiting (LEO) satellite system and uses Code Division Multiple Access (CDMA) to allocate system resources to the maximum …
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Navigation using Radio-Frequency Observables from LEO Constellations with Possible Aiding from an Inertial Navigation System
… of using radio-frequency signals from massive LEO satellite constellations. This work aids in the creation of a navigation system independent of current GNSS. A tightly-coupled carrier Doppler shift/INS filter is developed to determine the feasibility of using signals of opportunity from LEO …
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Exploiting Signals of Opportunity for High-Precision PNT: Optimized Bayesian Estimation Across 5G and LEO Networks
… systems. While traditional global navigation satellite systems (GNSS) degrade severely in deep urban canyons, emerging terrestrial 5G millimeter-wave and non-terrestrial low Earth orbit (LEO) satellite signals of opportunity offer highly promising alternatives. However, the practical …
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Emergence of second-generation low earth orbit satellite constellations : a prospective technical, economic, and policy analysis
Modern proposals for Low Earth Orbit (LEO) satellite constellations underscore the tremendous potential and versatility of distributed spacecraft missions (DSMs), but they have also begun to stress the limits of the existing development paradigm. A new generation of LEO constellations is emerging, …
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Development and Testing of A Space-borne GPS Signal Strength Sensor
The Global Positioning System (GPS) satellite signals provide not only traditional radionavigation service but inexpensive and convenient radio beacons for signal propagation studies on ionosphere and atmosphere. This thesis describes the development and testing of a specialized GPS sensor which …
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Low-Cost Real-Time Precise Point Positioning (PPP) Correction Service with High Availability and Accuracy
… to represent and disseminate real-time precise satellite orbit, clock, and code bias with improved availability and scalability. The ILNAV can provide real-time precise satellite orbit and clock corrections for up to two hours when correction outages occur. The update rates of the ILNAV are …
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Atomic Oxygen Considerations for LEO De-orbit Trajectories Using Solar Sails
… solar sail technology, they could be deployed on LEO satellites higher than 600 km to help de-orbit the satellite within 25 years upon mission termination. To determine how atomic oxygen would affect the solar sail, material from Lightsail-2 was tested in a thermal-energy, isotropic, atomic oxygen …
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Towards Resilient and Secure Beyond-5G Non-Terrestrial Networks (B5G-NTNs): An End-to-End Cloud-Native Framework
… services. NTNs, including Low Earth Orbit (LEO) satellites, Unmanned Aerial Vehicles (UAVs), and High Altitude Platform Systems (HAPS), extend traditional terrestrial networks by providing continuous connectivity in remote, underserved, and connection-critical scenarios such as disaster-hit …
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