Article
Engineering, Aerospace
Kan Wang, Ahmed El-Mowafy, Xuhai Yang
Summary: The study assesses various reduced-dynamic prediction strategies for three different-altitude test LEO satellites using real data, selecting appropriate methods for different prediction times up to 6 hours. Global-averaged orbital user range errors (OUREs) are shown to be altitude-related. A proposed algorithm considering the Earth as an Ellipsoid is used to calculate the worst-location OURE for predicted orbits.
ADVANCES IN SPACE RESEARCH
(2022)
Article
Remote Sensing
Jinyun Guo, Linhu Qi, Xin Liu, Xiaotao Chang, Bing Ji, Fangzhao Zhang
Summary: This study investigated the impact of ionospheric delay on the precise orbit determination (POD) of low earth orbit (LEO) satellites. The ionospheric-free linear combination was used to eliminate the influence of the first-order main term, while considering the higher-order ionospheric (HOI) delay. The results show that the HOI delay has an impact on LEO satellite GPS data at the millimeter to centimeter level. The correction of HOI delay can improve the precision of POD.
Article
Geochemistry & Geophysics
Xiaodong Ren, Hang Liu, Jincheng Zhang, Dengkui Mei, Xiaohong Zhang
Summary: This paper proposes an improved method to estimate ionospheric TEC over oceans using the GNSS-R technique by considering the influence of tropospheric delays and topside ionospheric delays. The results show that this method significantly improves the accuracy of TEC compared to other models and measured data.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2022)
Article
Computer Science, Information Systems
Shengyu Zhang, Kwan L. Yeung
Summary: This paper proposes a scalable two-layer routing architecture to address the dynamic nature of low-Earth orbit satellite constellations (LEO-SCs). Two stable routing algorithms are designed to minimize route changes.
COMPUTER COMMUNICATIONS
(2022)
Article
Multidisciplinary Sciences
Kutubuddin Ansari, Hong-Woo Seok, Punyawi Jamjareegulgarn
Summary: In this study, a comparative analysis was conducted on the tide-gauge measurements retrieved by quasi-zenith satellite system-reflectometry (QZSS-R) and the legacy tide gauges. The results showed that QZSS-R signals provided precise results similar to those of GPS-R and GLONASS-R. A machine learning technique called kernel extreme learning machine (KELM) was implemented to reconstruct the tidal variability for QZSS-R measurements, and the results showed high correlation coefficients with the tide-gauge measurements. This proposed method seems to be effective in obtaining dense tide-gauge estimations.
SCIENTIFIC REPORTS
(2022)
Article
Remote Sensing
Jorge Mendez-Astudillo, Lawrence Lau, Yu-Ting Tang, Terry Moore
Summary: The Urban Heat Island (UHI) effect refers to higher temperatures in urban areas compared to rural surroundings due to heat absorption by built structures and anthropogenic sources. Monitoring UHI intensity is crucial to address its adverse effects on human health and energy consumption. This paper presents a three-step algorithm utilizing Global Navigation Satellite Systems (GNSS) data for UHI intensity monitoring, offering advantages of increased observational data availability, high temporal and geographical resolution. The algorithm has been tested and validated in Los Angeles, California, achieving an accuracy of 1.71 degrees C at 95% confidence level through comparison with temperature data from weather stations.
INTERNATIONAL JOURNAL OF APPLIED EARTH OBSERVATION AND GEOINFORMATION
(2021)
Article
Engineering, Aerospace
Taha Yasini, Jafar Roshanian, Amir Taghavipour
Summary: This study proposes a novel control system for satellite motion on the reference orbit (RO) using a comprehensive model of its dynamics and a Non-linear Model Predictive Controller (NMPC). The NMPC calculates sub-optimal control inputs by minimizing a convex cost function at each stage. The weighting parameters of the cost function are optimized using a Genetic Algorithm (GA) to improve the NMPC performance. The results show that the implemented NMPC can resist larger errors and perturbations, and compensate for those errors by returning the satellite to its main orbit.
ADVANCES IN SPACE RESEARCH
(2023)
Article
Engineering, Electrical & Electronic
Israel Leyva-Mayorga, Beatriz Soret, Petar Popovski
Summary: The future of wireless communications will heavily rely on dense satellite constellations deployed in low Earth orbit (LEO). While efforts to integrate satellites into 5G networks are promising, challenges such as dynamic inter-plane inter-satellite links need to be addressed. The proposed algorithms in this paper show significant improvements in both interference-free and worst-case scenarios for interference, increasing the sum of rates in the constellation by up to 115% and 71% respectively.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2021)
Article
Astronomy & Astrophysics
Xiaodong Ren, Dengkui Mei, Hang Liu, Xiaohong Zhang
Summary: Global Navigation Satellite System (GNSS) observations have been widely used in detecting traveling ionospheric disturbances (TID). However, interpreting the global propagation characteristics of large-scale TIDs (LSTIDs), especially over the ocean, has been challenging due to the lack of coverage in these observations. In this study, ground-based GNSS observations were combined with in situ data and GNSS observations from Low-Earth-Orbit (LEO) satellites to investigate LSTIDs during a geomagnetic storm. The results showed that LEO satellite observations effectively compensate for areas where ground-based GNSS data is sparse, particularly over the ocean and polar regions.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2022)
Article
Computer Science, Information Systems
Linhu Qi, Jinyun Guo, Yaowei Xia, Zhouming Yang
Summary: This paper presents an effective method to calculate higher-order ionospheric delay of GRACE-FO observation, which improves satellite orbit determination precision by calculating total electron content and magnetic field strength.
Review
Computer Science, Information Systems
Ali Lalbakhsh, Andrew Pitcairn, Kaushik Mandal, Mohammad Alibakhshikenari, Karu P. Esselle, Sam Reisenfeld
Summary: The proliferation of low-earth orbit satellites and the LEO satellite internet will have a significant impact on the global internet. This article focuses on the satellite brightness issue caused by LEO constellations, which potentially affect astronomical studies. It reviews the underlying contributors to satellite brightness and discusses state-of-the-art technologies proposed to address this emerging challenge.
Article
Environmental Sciences
Fabricio S. Prol, M. Mainul Hoque, Manuel Hernandez-Pajares, Liangliang Yuan, German Olivares-Pulido, Axel von Engeln, Christian Marquardt, Riccardo Notarpietro
Summary: In this study, the MetOp-A satellite is used to monitor the ionosphere using radio-occultation measurements. The collected data is compared with other missions and the spatial/temporal distributions are explored. Validation against independent products from other satellites is performed, and significant findings including agreement with Fengyun-3D measurements, S-shape bending angle variations, and observations of sporadic E-layer signatures are reported.
Article
Geochemistry & Geophysics
Heng Yang, Manuel Hernandez-Pajares, Wojciech Jarmolowski, Pawel Wielgosz, Sharon L. Vadas, Oscar L. Colombo, Enric Monte-Moreno, Alberto Garcia-Rigo, Victoria Graffigna, Anna Krypiak-Gregorczyk, Beata Milanowska, Pau Bofill-Soliguer, German Olivares-Pulido, Qi Liu, Roger Haagmans
Summary: This article demonstrates the capability of a global navigation satellite system (GNSS) precise orbit determination (POD) low Earth orbit (LEO) data in detecting anomalous ionospheric disturbances associated with earthquakes and tsunamis. The new PIES approach is utilized to confirm the significance of ionospheric signals above the swarm LEOs, supported by in situ electron density measurements and ground-based GNSS colocated measurements. The study also suggests the possible detection of tsunami-related ionospheric gravity waves in the Papua New Guinea 2016 event, consistent with recent theories. Furthermore, it highlights the feasibility of a future monitoring system for ionospheric disturbances using CubeSats with POD GNSS receivers and ground GNSS receivers.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2022)
Article
Geochemistry & Geophysics
Yunqiao He, Fan Gao, Tianhe Xu, Xinyue Meng, Nazi Wang
Summary: Global navigation satellite system reflectometry has the potential to provide high-precision sea surface height measurements. This study proposes a coastal GNSS-R altimetry algorithm using signals from the Quasi-Zenith Satellite System GEO satellite to overcome the issue of phase unwrapping errors. Experimental results show that the algorithm achieves accurate sea level estimation with a root mean square error of 1.4 cm.
IEEE GEOSCIENCE AND REMOTE SENSING LETTERS
(2022)
Article
Telecommunications
Jianfeng Shi, Husheng Yang, Chengsheng Pan, Xiao Chen, Qian Sun, Zhaohui Yang, Wei Xu
Summary: Satellite assisted Wireless Networks (SaWNs) are considered as an important part of the next generation wireless communication systems, providing global connectivity and multi-domain interconnection. This letter proposes a downlink transmission framework for SaWNs to achieve low-latency transmission for virtual reality (VR) applications, with satellite and femtocell responsible for outdoor and indoor communications respectively. By designing the user association and serving strategy and using convex optimization and Q-learning methods, a delay-minimization problem is formulated and solved. Simulation results show that our proposed algorithm can significantly reduce transmission delay compared to conventional benchmark algorithms and well meet the VR latency requirement.
IEEE COMMUNICATIONS LETTERS
(2023)
