November 2023
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20 Reads
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2 Citations
Engineering Applications of Artificial Intelligence
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November 2023
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20 Reads
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2 Citations
Engineering Applications of Artificial Intelligence
October 2023
September 2023
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22 Reads
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8 Citations
IEEE Vehicular Technology Magazine
Recently, megaconstellations with a massive number of low Earth orbit (LEO) satellites are being considered as a possible solution for providing global coverage due to relatively low latency and high throughput compared to geosynchronous orbit (GEO) satellites. However, as the number of satellites and operators participating in the LEO constellation increases, inter-satellite interference will become more severe, which may yield marginal improvement or even decrement in network throughput. In this article, we introduce the concept of satellite clusters that can enhance network performance through satellites’ cooperative transmissions. The characteristics, formation types, and transmission schemes for the satellite clusters are highlighted. Simulation results evaluate the impact of clustering from coverage and capacity perspectives, showing that when the number of satellites is large, the performance of clustered networks outperforms the unclustered ones. The viable network architectures of the satellite cluster are proposed based on the 3rd Generation Partnership Project (3GPP) standard. Finally, the future applications of clustered satellite networks are discussed.
May 2023
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7 Reads
This paper considers a downlink satellite communication system where a satellite cluster, i.e., a satellite swarm consisting of one leader and multiple follower satellites, serves a ground terminal. The satellites in the cluster form either a linear or circular formation moving in a group and cooperatively send their signals by maximum ratio transmission precoding. We first conduct a coordinate transformation to effectively capture the relative positions of satellites in the cluster. Next, we derive an exact expression for the orbital configuration-dependent outage probability under the Nakagami fading by using the distribution of the sum of independent Gamma random variables. In addition, we obtain a simpler approximated expression for the outage probability with the help of second-order moment-matching. We also analyze asymptotic behavior in the high signal-to-noise ratio regime and the diversity order of the outage performance. Finally, we verify the analytical results through Monte Carlo simulations. Our analytical results provide the performance of satellite cluster-based communication systems based on specific orbital configurations, which can be used to design reliable satellite clusters in terms of cluster size, formation, and orbits.
May 2023
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27 Reads
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7 Citations
January 2023
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21 Reads
Recently, mega-constellations with a massive number of low Earth orbit (LEO) satellites are being considered as a possible solution for providing global coverage due to relatively low latency and high throughput compared to geosynchronous orbit satellites. However, as the number of satellites and operators participating in the LEO constellation increases, inter-satellite interference will become more severe, which may yield marginal improvement or even decrement in network throughput. In this article, we introduce the concept of satellite clusters that can enhance network performance through satellites' cooperative transmissions. The characteristics, formation types, and transmission schemes for the satellite clusters are highlighted. Simulation results evaluate the impact of clustering from coverage and capacity perspectives, showing that when the number of satellites is large, the performance of clustered networks outperforms the unclustered ones. The viable network architectures of the satellite cluster are proposed based on the 3GPP standard. Finally, the future applications of clustered satellite networks are discussed.
January 2023
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10 Reads
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2 Citations
January 2023
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10 Reads
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4 Citations
IEEE Access
In this paper, we propose random beam-based non-orthogonal multiple access (NOMA) for massive multiple-input multiple-output (MIMO) low earth orbit (LEO) satellite communication systems that operate with frequency-division duplexing (FDD). Our system model consists of a massive-antenna satellite and multiple single-antenna users within its coverage area. The satellite selectively serves a subset of users based on a target signal-to-interference-plus-noise power ratio (SINR). In the random beam-based NOMA, the satellite utilizes random beams, where each beam can support multiple users using NOMA. To facilitate user selection and power allocation, each user provides several scalar values obtained from statistical channel state information (CSI) as feedback to the satellite. This allows us to reduce the computational complexity of beamforming design and minimize the feedback overhead for channel acquisition. We propose two random beam-based NOMA schemes with varying complexities and feedback overheads. We optimize these schemes by solving joint user selection and power allocation problems. The numerical results demonstrate that our proposed schemes outperform conventional random beamforming, specifically orthogonal multiple access (OMA) at each beam, by supporting a greater number of users.
January 2023
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19 Reads
IEEE Wireless Communications Letters
This paper considers a downlink satellite communication system where a satellite cluster, i.e., a satellite swarm consisting of one leader and multiple follower satellites, serves a ground terminal. The satellites in the cluster form either a linear or circular formation moving in a group and cooperatively sending their signals by maximum ratio transmission precoding. We first conduct a coordinate transformation to effectively capture the relative positions of satellites in the cluster. Next, we derive an exact expression for the orbital configuration-dependent outage probability under the Nakagami fading by using the distribution of the sum of independent Gamma random variables. In addition, we obtain a simpler approximated expression for the outage probability with the help of second-order moment-matching. We also analyze asymptotic behavior in the high signal-to-noise ratio regime and the diversity order of the outage performance. Finally, we verify the analytical results through Monte Carlo simulations. Our analytical results provide the performance of satellite cluster-based communication systems based on specific orbital configurations, which can be used to design reliable satellite clusters in terms of cluster size, formation, and orbits.
October 2022
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7 Reads
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1 Citation
... Recently, the use of satellite communication has been considered for remote power plants and factories [1] as a non-terrestrial network (NTN) system. To increase the satellite channel capacity required for such applications, multiple-input multipleoutput (MIMO) technology using low-Earth orbit (LEO) satellites has been actively studied [2][3][4][5]. These include the study of MIMO transmission using a multi-beam antenna in one LEO satellite [2, 3], multiple-satellite MIMO using multiple single beams from multiple LEO satellites [4], and distributed massive MIMO technology [5], which uses multiple LEO satellites in a cluster for cooperative transmission. ...
January 2023
IEEE Access
... The common knowledge-guided framework includes supplementing the input information with additional data sources, such as satellite imagery, in-situ sensors, and reanalysis datasets, to capture the multimodal nature of the data (Duan et al. 2024;Kim et al. 2023). Integrating auxiliary variables like geographic coordinates, elevation, meteorological variables, and other contextual information into the generative model helps ensure the physical plausibility of the generated outputs (Ge et al. 2022). ...
May 2023
... This large number of diverse platforms imposes exceptional technical challenges on system control and operation, where they need to be built on an autonomous and dynamic network architecture [77]. Therefore, these various space and aerial platforms can be interconnected via inter-aerial links (IALs), inter-satellite link (ISLs) and inter-orbit links (IOLs) to construct a multi-layered integrated NTNs, which can support real-time communications, massive data transmission, and systematized information services [78]. Establishing multi-layered NTNs to connect multitude of platforms in different orbits/altitudes will enable combining multiple space/aerial assets to allow a more agile and efficient use of system resources [79]. ...
September 2023
IEEE Vehicular Technology Magazine
... In recent years, Low Earth Orbit (LEO) satellite communication has attracted a myriad of interest due to its ability to provide both high-performance communication and widespread location-based services around the world [1]- [6]. Long-range technology (LoRa) is becoming one of the promising candidates for use in LEO systems due to its low power consumption and long range, making it suitable for a wide range of Internet of Things (IoT) applications. ...
January 2023
... Since the physical layer plugin can be further developed, all mathematical formulas and algorithms we used here are just for reference. The mathematical formula governing the antenna pattern in Plotinus is expressed as follows [20] : ...
October 2022
... Later in [19], a simpler model for the shadowed-Rician fading with modeling the LOS component amplitude with a Nakagami distribution has been proposed. These two models have been used in the literature to analyze the performance of satellite communication systems [20]- [24]. ...
April 2022
IEEE Transactions on Communications
... They used Cox point processes to model the spatial distribution of satellites and formulated an optimization problem to maximize the network capacity while satisfying coverage requirements (Saeed et al., 2021). The authors employed a genetic algorithm to find the optimal solution (Jung et al., 2022). Zhu et al. (2022) focused on the optimization of multi-altitude satellite constellations for global coverage and minimum total inter-satellite interference. ...
January 2022
IEEE Transactions on Information Forensics and Security
... In addition, an increasing number of studies have used 10 m surface winds as the primary dynamic factor in the spatiotemporal SWH prediction due to the close correlation between SWH and winds (e.g., Bethel et al., 2021;Laface and Arena, 2021;Wei and Chang, 2021). Kim et al. (2022) and Han et al. (2022) improve the prediction accuracy in the calculation of SWH at a leading time of 1-48h by incorporating both historical winds and SWH as input to the ConvLSTM algorithm. This study, however, does not update future winds, leading to rapid development in the prediction errors over time. ...
August 2022
Ocean Engineering
... 3) для этих двух случаев статистически не различимо, коэффициент корреляции между истинными и прогнозируемыми значениями меняется в диапазоне (0.5-0.9), со средним 0.7. Это превосходит современный уровень точности прогнозов Эль-Ниньо, где коэффициент корреляции падает ниже 0.5 при прогнозировании далее чем на год [12]. Поскольку истинные значения в этом варианте не использовались для дообучения сети, точность прогноза падает с ростом его длительности. ...
May 2022
Scientific Reports
... The third generation partnership project (3GPP) has initiated standardization for non-terrestrial networks (NTN), aiming to provide global wireless access beyond geographical limitations [1]. Owing to the limitations of terrestrial networks, particularly during emergencies with potential failure of pre-existing facilities, and high expansion costs in remote regions, the 6G NTN system has emerged as an effective resolution. ...
February 2022