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
Chemistry, Analytical
Grzegorz Grunwald, Adam Ciecko, Tomasz Kozakiewicz, Kamil Krasuski
Summary: This research focuses on the analysis of the positioning quality of a modified GPS/EGNOS algorithm, with considerations given to different ionospheric models. The results show that the original EGNOS ionospheric model maintains the best accuracy and correlation between horizontal and vertical results among the models examined.
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
Environmental Sciences
Kan Wang, Ahmed El-Mowafy, Xuhai Yang
Summary: High-accuracy Low Earth Orbit (LEO) satellite clock and orbital products are essential for high-accuracy GNSS-based positioning on the ground. This study investigates the benefits of modeling high-stability LEO satellite clocks to reduce short-term noise and mis-modeled effects. The results show that detrending the clocks with a smoothing window of 300 to 500 s and applying a PWL model with a length from 300 to 1200 s can improve radial orbit estimation by more than 10%.
Article
Environmental Sciences
Shan Wang, Ding Wang, Junren Sun
Summary: In this article, an artificial neural network (ANN) method is proposed for deriving ionospheric delay and vertical errors. Experimental results show that under normal ionospheric conditions, the ANN method outperforms traditional methods in terms of fitting accuracy and availability. However, under disturbed conditions, the performance of the ANN method is less satisfactory compared to conventional methods.
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
Computer Science, Information Systems
Nasrin Razmi, Bho Matthiesen, Armin Dekorsy, Petar Popovski
Summary: This paper discusses the use cases of federated learning in Low Earth Orbit (LEO) mega constellations, specifically in satellite imaging inference. It proposes a new algorithm based on FedAvg that utilizes an asynchronous federated learning procedure, improving the robustness in heterogeneous scenarios. Extensive numerical evaluations using MNIST and CIFAR-10 datasets demonstrate the fast convergence speed and high test accuracy of the proposed method.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Fabricio S. Prol, Artem Smirnov, Sanna Kaasalainen, Mohammad Mainul Hoque, Mohammad Zahidul H. Bhuiyan, Francesco Menzione
Summary: The rapid increase in the number of low Earth orbit (LEO) satellites enables the transmission of dedicated signals for positioning, navigation, and timing (PNT), as well as unique measurements of the Earth's upper atmosphere. This study explores the benefits of highly dense LEO-PNT systems for 3-D ionospheric imaging using total electron content (TEC) measurements. The inclusion of LEO satellites in the system geometry improves the ionospheric imaging system, and accurate 3-D electron density representation can be obtained even without horizontal viewing angles.
IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING
(2023)
Article
Engineering, Electrical & Electronic
Yong Lu, Youjian Zhao, Fuchun Sun, Faquan Yang, Ruishi Liang, Jun Shen, Zhihong Zuo
Summary: This paper proposes structural optimization methods for Two-Layered Satellite Networks (TLSNs) to enhance the transmission efficiency of Mega-constellation LSNs. The proposed methods not only effectively improve the transmission efficiency, but also increase the duration time of Inter-Layer Links (ILLs) and reduce the topological dynamics of TLSNs.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2022)
Article
Environmental Sciences
Junqi Guo, Yang Wang, Chenyang Sun
Summary: This study aims to solve the optimal positioning configuration problem for large-scale satellite selection using a genetic algorithm and proposes a new positioning configuration formula. The research finds that the traditional recursive algorithm is not applicable in large-scale constellations, while the proposed formula has a similar accuracy to the Quasi-Optimal algorithm when there is no signal occlusion and the satellites are uniformly selected, effectively overcoming accuracy loss under signal occlusion.
Article
Engineering, Electrical & Electronic
Ruoqi Deng, Boya Di, Hongliang Zhang, Linling Kuang, Lingyang Song
Summary: This paper investigates a terrestrial-satellite network based on ultra-dense LEO satellites and proposes a three-dimensional constellation optimization algorithm to reduce the number of satellites, with simulation results confirming its effectiveness. The study shows that the proposed LEO satellite constellation has a higher coverage ratio compared to the Telesat constellation.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2021)
Article
Environmental Sciences
Manuel Hernandez-Pajares, German Olivares-Pulido, M. Mainul Hoque, Fabricio S. S. Prol, Liangliang Yuan, Riccardo Notarpietro, Victoria Graffigna
Summary: This paper presents a novel technique to estimate DCBs from GPS transmitters and receivers on-board LEO satellites, which is in full agreement with results reported independently with other techniques. The technique involves obtaining the DCBs as residuals from the difference between the ionospheric combination of the code and the associated ionospheric delay. The ionospheric delay is computed with TOMION, a background-model-free ionospheric tomographic technique based on dual-frequency GPS carrier phase data only, and solved with a Kalman filter.
Article
Geochemistry & Geophysics
Xiaodong Ren, Jincheng Zhang, Jun Chen, Xiaohong Zhang
Summary: High accuracy and resolution global ionosphere model is crucial for ionospheric research and GNSS precise positioning. Combining LEO and GNSS observation data improves model accuracy significantly, with SLN and DLS methods reducing root mean square error by about 25x0025; and 21x0025; respectively.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2022)
Article
Computer Science, Information Systems
Peng He, Jiaojiao Hu, Xinyue Fan, Dapeng Wu, Ruyan Wang, Yaping Cui
Summary: Low earth orbit (LEO) satellite networks are a hot research area in satellite communication networks. This research proposes a load-balanced collaborative offloading (LBCO) strategy, which consists of two algorithms, CAGFA and ISLCO, to achieve balanced traffic distribution and download observation data. Simulation results show that the LBCO strategy improves weighted utility and convergence compared to benchmark algorithms, and performs well under different load scenarios.
IEEE INTERNET OF THINGS JOURNAL
(2023)
Article
Engineering, Electrical & Electronic
Jianming Guo, David Rincon, Sebastia Sallent, Lei Yang, Xiaoqian Chen, Xianqi Chen
Summary: This paper proposes a gateway placement optimization method for LEO satellite networks, aiming to balance traffic loads and minimize the number of gateways. It utilizes a gravity model and modifies the discrete particle swarm optimization algorithm to solve the problem, with successful results in numerical tests on real satellite constellations.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2021)
Article
Engineering, Aerospace
Mingyu Kim, Jeongrae Kim
INTERNATIONAL JOURNAL OF AEROSPACE ENGINEERING
(2017)
Article
Environmental Sciences
Mingyu Kim, Jeongrae Kim
Summary: This study proposes a method to extend the SBAS ionosphere correction coverage using an extrapolation algorithm, successfully reducing ionospheric errors at low latitudes and improving positioning accuracy.
Article
Chemistry, Analytical
Beomsoo Kim, Jeongrae Kim
Summary: We propose an adjustment method to make real-time service data continuous, and combine it with long-short-term memory network to improve the prediction accuracy. Experimental results show the effectiveness of the proposed method in orbit prediction.
