Satellite Communication Research Articles

Technological communication on low-intensity railway sections

The purpose of the study is to develop proposals for increasing the efficiency of the functioning of low-intensity railway sections (LIRS) by improving technological communication systems, taking into account the specifics of train traffic control on LIRS, as well as assessing the possibilities of using short-wave ionospheric radio communications and satellite communications in remote and extended LIRS. The study used methods for analyzing the characteristics of LIRS existing on Russian railways, methods for assessing radio communication channels based on Russian and international experience. As a result of the research, a classification of LIRS was proposed from the point of view of options for organizing technological radio communication systems on them, a unified scheme for constructing a radio communication system on LIRS was developed, and an algorithm was compiled for selecting the optimal option for the radio communication system in relation to each specific LIRS.

Satellite Communications with 5G, B5G, and 6G: Challenges and Prospects

Satellite Communications with 5G, B5G, and 6G: Challenges and Prospects

Simulation of displacement damage of InP induced by protons and α-particles in low Earth orbit

Indium phosphide (InP) material hasmany advantages, such as large band gap, high electron mobility, high photoelectric conversion efficiency, high temperature resistance, and radiation resistance, which is superior to silicon (Si) and gallium arsenide (GaAs). Meanwhile InP is widely used in optical communication, high-frequency millimeter waves, optoelectronic integrated circuits, satellite communication, space solar cells, and other fields. Radiation particles incident on InP device can generate displacement atoms inside the device through elastic processes. And these displacement atoms continue cascade collisions to generate lattice defects which are vacancies, interstitials, and clusters. These defects capture electrons-holes by defective energy levels in the energy band, and then resulting in a decrease in the life of minority carriers which is the reason of degradation of InP devices. The process of degradation of InP device, induced by lattice defects from ion-irradiation, is called displacement damage effect (DDE). The non-ionizing loss energy (NIEL) scaling is a useful method to predict the degradation of device caused by DDE of radiation particles. Many studies have shown that the NIEL is linearly related to the damage coefficient of InP device. Previous studies of radiation damage effect of InP device mainly focused on single-energy protons, electrons, and neutrons. Of the particles in low earth orbit (LEO),the vast majority of particles are protons, with a few being α particles and electrons, while the electron’s NIEL is too small and its DDE is negligible. The InP’s NIEL induced by proton and α energy in LEO has not been studied in detail. Therefore, this paper uses Monte Carlo software Geant4 to study the NIEL, damage energy distribution with depth, and annual total non-ionization loss energy generated by protons and α particles in LEO in 500/1000/5000 μm InP materials. The shielding of 150-μm-thick SiO<sub>2</sub> layer and 2.54-mm-thick Al layer from protons and α particles are used as InP solar cell and InP devices in spacecraft, respectively. It is found that the energy spectrum determines the non-ionizing damage energy <inline-formula><tex-math id="M1">\begin{document}$ {T}_{\text{dam}} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20231499_M1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20231499_M1.png"/></alternatives></inline-formula> distribution, and then influences the NIEL value: the NIEL value increases with <inline-formula><tex-math id="M2">\begin{document}$ {T}_{\text{dam}} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20231499_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20231499_M2.png"/></alternatives></inline-formula> increasing and thickness of InP material decreasing. And α NIEL is larger than proton’s, the single particle DDE of InP device, induced by α particles, should be concerned. The annual non-ionizing damage energy of proton accounts for 98%, which means that proton is the main factor degrading InP devices in LEO.

Synchronization in PLL Networks: Numerical Simulations Using Julia

Clock distribution systems are used in many applications requiring accurate time basis: integrated circuits, computer networks, satellite communications, and Global Position System (GPS). Trying to automatize the design of clock distribution systems, this work presents a general formulation considering the possible topologies and parameters, building a computational tool allowing to design and evaluate the performance of any case to be studied. The developed tool enables to simulate networks setting the number of nodes, internal node parameters, topology, perturbations, and signal propagation delays. The simulation results include response times, synchronization quality, and stability for all types of arrangements: mutually connected, chains, rings, stars, and mixed architectures.

Multibeam Beamforming for Direct Radiating Arrays in Satellite Communications Using Genetic Algorithm

Multibeam Beamforming for Direct Radiating Arrays in Satellite Communications Using Genetic Algorithm

US Satellites during the Crisis: Outer Space Cyber Threats

Against the background of significant dynamic changes in the use of outer space by mankind, the transformation of outer space into a sphere of military confrontation becomes not a danger of the distant future, but a real urgent threat. Important characteristics of the current stage are the ubiquity and significant growth in the number of artificial Earth satellites, which solve more and more research and applied tasks, as well as the steady increase in the importance of applied satellites used for military purposes. The most important role among them is played by communication satellites, navigation, remote sensing of the Earth (remote sensing), as well as satellites of the Early warning system. In the course of military operations, artificial Earth satellites serve to ensure combat operations and the combat use of various means of armed struggle. The United States has the largest satellite grouping. The analysis presented in the article of the capabilities of modern US artificial satellite systems, as well as their destructive use during a military conflict, allows us to conclude that the risk of threats to international security is increasing. In addition, the facts of the destabilizing use of artificial satellites by the United States of America and other NATO countries to achieve their military and political goals increase the likelihood of an escalation of the conflict and are associated at the current stage with threats to Russia and strategic stability. Against the background of other urgent challenges and threats, this poses a number of global problems posed in this study as acutely as possible. The article presents the characteristics of the current stage of space use; the possibilities of the US ISP during the crisis, which serve to provide various means of armed struggle, are identified; the problems of using the US ISP in the current situation are posed. Proposals have been developed to minimize threats and reduce the likelihood of escalation of the conflict.

Priority-Aware Parallel Transmission towards Dense Satellite Remote Sensing and Communication Integrated Networks

Priority-Aware Parallel Transmission towards Dense Satellite Remote Sensing and Communication Integrated Networks

Vision-Based UAV Self-Positioning in Low-Altitude Urban Environments.

Unmanned Aerial Vehicles (UAVs) rely on satellite systems for stable positioning. However, due to limited satellite coverage or communication disruptions, UAVs may lose signals for positioning. In such situations, vision-based techniques can serve as an alternative, ensuring the self-positioning capability of UAVs. However, most of the existing datasets are developed for the geo-localization task of the objects captured by UAVs, rather than UAV self-positioning. Furthermore, the existing UAV datasets apply discrete sampling to synthetic data, such as Google Maps, neglecting the crucial aspects of dense sampling and the uncertainties commonly experienced in practical scenarios. To address these issues, this paper presents a new dataset, DenseUAV, that is the first publicly available dataset tailored for the UAV self-positioning task. DenseUAV adopts dense sampling on UAV images obtained in low-altitude urban areas. In total, over 27K UAV- and satellite-view images of 14 university campuses are collected and annotated. In terms of methodology, we first verify the superiority of Transformers over CNNs for the proposed task. Then we incorporate metric learning into representation learning to enhance the model's discriminative capacity and to reduce the modality discrepancy. Besides, to facilitate joint learning from both the satellite and UAV views, we introduce a mutually supervised learning approach. Last, we enhance the Recall@K metric and introduce a new measurement, SDM@K, to evaluate both the retrieval and localization performance for the proposed task. As a result, the proposed baseline method achieves a remarkable Recall@1 score of 83.01% and an SDM@1 score of 86.50% on DenseUAV. The dataset and code have been made publicly available on https://github.com/Dmmm1997/DenseUAV.

Prediction of physical realizations of the coordinated universal time with gated recurrent unit.

Coordinated Universal Time (UTC), produced by the Bureau International des Poids et Mesures (BIPM), is the official worldwide time reference. Given that there is no physical signal associated with UTC, physical realizations of the UTC, called UTC(k), are very important for demanding applications such as global navigation satellite systems, communication networks, and national defense and security, among others. Therefore, the prediction of the time differences UTC-UTC(k) is important to maintain the accuracy and stability of the UTC(k) timescales. In this paper, we report for the first time the use of a deep learning (DL) technique called Gated Recurrent Unit (GRU) to predict a sequence of H futures values of the time differences UTC-UTC(k) for ten different UTC(k) timescales. UTC-UTC(k) time differences published on the monthly Circular T document of the BIPM are used as training samples. We utilize a multiple-input, multiple-output prediction strategy. After a training process where about 300 past values of the difference UTC-UTC(k) are used, H (H = 6) values of the Circular T can be predicted using p (typically p = 6) past values. The model has been tested with data from ten different UTC(k) timescales. When comparing GRU results with other standard DL algorithms, we found that the GRU approximation has a good performance in predicting UTC(k) timescales. According to our results, the GRU error in predicting UTC-UTC(k) values is typically 1ns. The frequency instability of the UTC(k) timescale is the main limitation in reducing the GRU error in the time difference prediction.

Wideband Dual-Polarized Planar Phased Array Using Filtenna Elements for Vehicular Satellite Communications

Wideband Dual-Polarized Planar Phased Array Using Filtenna Elements for Vehicular Satellite Communications

Dynamic LSTM-Based Channel Quality Indicators Prediction for LEO Satellite Communication

Dynamic LSTM-Based Channel Quality Indicators Prediction for LEO Satellite Communication

Design of Autoconfigurable Random Access NOMA for URLLC Industrial IoT Networking

Low power devices are massively deployed to facilitate real time sensing and data transmission requested in low power wide-area network (LPWAN). However, the dominating signaling, i.e. continuous phase modulation (CPM), barely gains attention in the context of supporting massive connectivity, not to mention ultra-reliable low-latency communications (URLLC), a primary concern in industrial network automation. To this end, auto-configurable nonorthogonal multiple access (AC-NOMA) based on CPM signaling is proposed. The term auto-configuration is used since each device selects a setup from a pool of configurations whenever connecting to the access point in a random and distributive way. It is proven, using ideal power allocation and phase shaping technique, AC-NOMA offers drastically improved user load and near capacity performance even in finite blocklength regime. Moreover, to enable massive yet sporadic access, slotted ALOHA is combined with AC-NOMA. It is proven that the resultant scheme outperforms power-domain NOMA in terms of throughput even with reduced transmit power and simple forward error correction schemes such as repetition and convolutional coding. The throughput is further improved using semi AC-NOMA with slightly increased latency. It is demonstrated that both designs can support very high user load while enabling URLLC in finite blocklength regime, where the packet size is merely 256 bits while the error rate is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$10^{-5}$</tex-math></inline-formula> , which are also desirable in a number of applications including satellite communications, visible light communications, etc.

Exploiting On-Orbit Characteristics for Joint Parameter and Channel Tracking in LEO Satellite Communications

Exploiting On-Orbit Characteristics for Joint Parameter and Channel Tracking in LEO Satellite Communications

Design of Energy Efficient Multi-HAPS Assisted Hybrid RF/FSO Satellite Communication Systems With Optimal Placement

Design of Energy Efficient Multi-HAPS Assisted Hybrid RF/FSO Satellite Communication Systems With Optimal Placement

Channel correlation based user grouping algorithm for nonlinear precoding satellite communication system

Channel correlation based user grouping algorithm for nonlinear precoding satellite communication system

Reduced-Complexity Decoding of 3D Product Codes for Satellite Communications

This paper aims to provide a reduced-complexity decoding for satellite communication systems to enhance system performance and transmission efficiency. By addressing the complexity, error rate, and latency issues for satellite communications, a novel 3-dimensional product decoding scheme is proposed. The density evolution algorithm is also introduced to analyze and optimize for the binary message passing decoding, which further reduces the computational complexity and latency. The simulation results show that the proposed method can obtain about 0.3- and 0.15-dB performance gains compared to the similar decodings of the conventional 2-dimensional BCH product codes and staircase codes, respectively. Our proposed coding scheme offers a broad prospect to the critical issues of transmission latency and data throughput in satellite networks.

New SRR/CSRR antenna dual Band-notch for WLAN and X Band Satellite communication

New SRR/CSRR antenna dual Band-notch for WLAN and X Band Satellite communication

Machine learning-inspired intelligent optimization for smart radio resource management in satellite communication networks to improve quality of service

Satellite communication networks are seeing a significant surge in traffic requirements. Nevertheless, the rise in traffic requirements is inconsistent across the service region because of the unequal distribution of consumers and fluctuations in traffic requirements during the day. Variable payload designs solve this issue by enabling the uneven allocation of payload resources to match the traffic requirement of each beam. Optimization-based Radio Resource Management (ORRM) has its high substantial efficiency demonstrated computational difficulty hinders its real-world deployment. This work explores the structure, execution, and uses of Machine Learning (ML) for resource allocation in satellite systems. The primary emphasis is on two systems: one that offers power, capacity, and beamwidth adaptability and provides temporal flexibility via beam hopping. The research examines and contrasts several ML methods suggested for these structures. The research determines whether training must be done online or offline depending on the features and needs of each ML method. The study analyzes the most suitable system structure and the pros and cons of each strategy.

Distributed Rate-Splitting Multiple Access for Multilayer Satellite Communications

Distributed Rate-Splitting Multiple Access for Multilayer Satellite Communications

Analysis of Integrated Differential Absorption Radar and Subterahertz Satellite Communications Beyond 6G

Analysis of Integrated Differential Absorption Radar and Subterahertz Satellite Communications Beyond 6G