Journal articles: 'Multi-beam satellite systems'

1

Wang, Renge, Minghao Chen, Luyan Xu, Zhong Wen, Yiyang Wei, and Shice Li. "Multi-Dimensional Resource Allocation for Covert Communications in Multi-Beam Low-Earth-Orbit Satellite Systems." Electronics 13, no. 17 (2024): 3561. http://dx.doi.org/10.3390/electronics13173561.

Full text

Abstract:

Satellite communication systems, especially multi-beam low-Earth-orbit (LEO) satellites, could cater to the needs of different industrial applications through flexible resource allocation. Unfortunately, due to the wide coverage of LEO satellites, the data exchange within the LEO satellite networks suffers from the risk of eavesdropping and malicious jamming, which could severely degrade the performance of the industrial production process. To address such challenges, this paper introduces a multi-dimensional resource allocation strategy to facilitate covert communication within the multi-beam LEO satellite network. Our approach ensures the rate requirements of different user equipments while preventing the detection of communication signals by an eavesdropping geostationary orbit (GEO) satellite. Specifically, we formulate an optimization problem that jointly optimizes satellite beam-hopping scheduling, frequency band allocation, and the transmit power of different user equipments, under the covertness constraint. By introducing auxiliary binary variables, we transform this optimization problem into a Mixed-Integer Linear Programming (MILP) problem, which allows us to utilize machine learning-based techniques for efficient solution finding. The simulation results demonstrate the effectiveness of our proposed scheme.

APA, Harvard, Vancouver, ISO, and other styles

2

Zhang, Haojie, Di Ren, and Fanghua Jiang. "A Beam Search-Based Channel Allocation Method for Interference Mitigation of NGSO Satellites with Multi-Beam Antennas." Aerospace 9, no. 4 (2022): 177. http://dx.doi.org/10.3390/aerospace9040177.

Full text

Abstract:

In the past few years, non-geostationary orbit (NGSO) satellite communication constellations have regained popularity due to their conspicuous advantages. Nevertheless, with more NGSO satellites getting involved in communications, the spectrum resources should become much more scarce. Multi-beam high throughput satellite and spectrum sharing are two major techniques in communication design. The two techniques can significantly mitigate interference and highly augment the capacity of the communication system. Thus, they are commonly used in satellite communication systems nowadays. With a massive number of NGSO satellites comprising the communication system and moving in their orbits, interference scenarios are pretty complex. In this article, the relationship between the level of interference and the beam distance is deduced. Moreover, for beams with different tilting angles, the different off-axis angles may correspond to the same beam distance, which is directly related to the interference level. Through the interference analysis, we propose a channel allocation method that uses a beam search algorithm to optimize the channel allocation problem and achieves outstanding time efficiency. The performance of the proposed method is validated by a coexisting scenario of the geostationary orbit and NGSO satellite communication systems. The results show that the level of interference can be largely mitigated, and the capacity of communication systems is significantly augmented.

APA, Harvard, Vancouver, ISO, and other styles

3

Zheng, Wei, Bin Li, Shu Bo Ren, Jiang Chen, and Jian Jun Wu. "Interference Modeling and Analysis for Inclined Projective Multiple Beams of GEO Satellite Communication Systems." Advanced Materials Research 756-759 (September 2013): 1204–9. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.1204.

Full text

Abstract:

In multi-beam satellite systems, Inter-Beam Interference (IBI) has a great effect on system performance. Within range of satellite coverage area, inclined projective multiple beams give rise to elliptic beam projections, resulting in that the distribution of beam projections is different from traditional cellular distribution. In this paper, an Inclined Projection (IP) model is proposed for IBI in OFDMA based GEO satellite communication systems, and corresponding analysis is also included. A comparison of carrier to interference power ratio (C/I) of users at the center of each cell with and without the consideration of IP is made, based on the simulation using different Frequency Reuse (FR) factor. The corresponding conclusions are presented. This research can provide reference for later satellite beam planning.

APA, Harvard, Vancouver, ISO, and other styles

4

Deng, Zhongliang, Xiaoyi Yu, Wenliang Lin, et al. "A Multi-Beam Satellite Cooperative Transmission Scheme Based on Resources Optimization and Packets Segmentation." Electronics 10, no. 22 (2021): 2841. http://dx.doi.org/10.3390/electronics10222841.

Full text

Abstract:

Multi-beam satellite communication systems are promising architectures in the future. A packet is transmitted by multi-satellite and multi-beam cooperatively, which can provide efficient spectrum utilization, improve system throughput, and guarantee Quality of Services (QoS). In multi-beam satellite communication systems, multi-layer and multi-dimensional radio resources change dynamically, which leads to the discontinuity of optimal resources and the lack of mapping balance between packets and radio resources. To deal with these problems, we propose a cross-layer and cross-dimension radio resources optimization model based on the weighted discrete firefly algorithm and an adaptive packet segmentation scheme based on the irregular gradient algorithm. The cross-layer and cross-dimension radio resources optimization model based on the weighted discrete firefly algorithm simulates cross-layer and cross-dimension optimization for the high-dynamic and multi-dimensional radio resources by considering the channel state information (CSI) and QoS in the multi-beam satellite communication system. The optimal resources are taken as the weight of irregular gradient algorithm to segment packets and map packets to radio resources, which can realize the mapping balance between packets and radio resources and ensure the efficiency and reliability of communication. The simulations show that the new transmission scheme improves the normalized system throughput and user satisfaction index by 18.7% and 6.2%, respectively.

APA, Harvard, Vancouver, ISO, and other styles

5

Теодорович, Н. Н., И. И. Ковалев, and А. Б. Семенов. "Optimization of the parameters of advanced multi-beam satellite systems." Informacionno-technologicheskij vestnik, no. 3(25) (September 17, 2020): 75–87. http://dx.doi.org/10.21499/2409-1650-2020-25-3-75-87.

Full text

Abstract:

Исследовано техническое обеспечение спутниковых многолучевых систем прямого направления и поставлена задача оптимизации параметров этих систем. На основе анализа параметров космического сегмента для абонентских лучей и структуры передающей части бортового ретранслятора предложены варианты частотно-поляризационного плана для улучшения энергетического потенциала спутниковой системы. Показаны способы увеличения зоны обслуживания луча исследуемых систем более чем в 2 раза. The technical support of satellite multi-beam systems of the forward direction is investigated and the problem of optimization of the parameters of these systems is set. Based on the analysis of the parameters of the space segment for subscriber beams and the structure of the transmitting part of the on-board repeater, variants of the frequency-polarization plan are proposed to improve the energy potential of the satellite system. Methods of increasing the service area of the beam of the systems under study by more than 2 times are shown.

APA, Harvard, Vancouver, ISO, and other styles

6

Zhou, Zhengyi, Wei Feng, Yunfei Chen, and Ning Ge. "Adaptive scheduling for millimeter wave multi-beam satellite communication systems." Journal of Communications and Information Networks 1, no. 3 (2016): 42–50. http://dx.doi.org/10.1007/bf03391569.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Wang, Heng, Aijun Liu, Xiaofei Pan, and Jianfei Yang. "Optimization of Power Allocation for Multiusers in Multi-Spot-Beam Satellite Communication Systems." Mathematical Problems in Engineering 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/780823.

Full text

Abstract:

In recent years, multi-spot-beam satellite communication systems have played a key role in global seamless communication. However, satellite power resources are scarce and expensive, due to the limitations of satellite platform. Therefore, this paper proposes optimizing the power allocation of each user in order to improve the power utilization efficiency. Initially the capacity allocated to each user is calculated according to the satellite link budget equations, which can be achieved in the practical satellite communication systems. The problem of power allocation is then formulated as a convex optimization, taking account of a trade-off between the maximization of the total system capacity and the fairness of power allocation amongst the users. Finally, an iterative algorithm based on the duality theory is proposed to obtain the optimal solution to the optimization. Compared with the traditional uniform resource allocation or proportional resource allocation algorithms, the proposed optimal power allocation algorithm improves the fairness of power allocation amongst the users. Moreover, the computational complexity of the proposed algorithm is linear with both the numbers of the spot beams and users. As a result, the proposed power allocation algorithm is easy to be implemented in practice.

APA, Harvard, Vancouver, ISO, and other styles

8

Xu, Huaixiu, Lilan Liu, and Zhizhong Zhang. "Service-Driven Dynamic Beam Hopping with Resource Allocation for LEO Satellites." Electronics 14, no. 12 (2025): 2367. https://doi.org/10.3390/electronics14122367.

Full text

Abstract:

Given the problems of uneven distribution, strong time variability of ground service demands, and low utilization rate of on-board resources in Low-Earth-Orbit (LEO) satellite communication systems, how to efficiently utilize limited beam resources to flexibly and dynamically serve ground users has become a research hotspot. This paper studies the dynamic resource allocation and interference suppression strategies for beam hopping satellite communication systems. Specifically, in the full-frequency-reuse scenario, we adopt spatial isolation techniques to avoid co-channel interference between beams and construct a multi-objective optimization problem by introducing weight coefficients, aiming to maximize user satisfaction and minimize transmission delay simultaneously. We model this optimization problem as a Markov decision process and apply a value decomposition network (VDN) algorithm based on cooperative multi-agent reinforcement learning (MARL-VDN) to reduce computational complexity. In this algorithm framework, each beam acts as an agent, making independent decisions on hopping patterns and power allocation strategies, while achieving multi-agent cooperative optimization through sharing global states and joint reward mechanisms. Simulation results show that the applied algorithm can effectively enhance user satisfaction, reduce delay, and maintain high resource utilization in dynamic service demand scenarios. Additionally, the offline-trained MARL-VDN model can be deployed on LEO satellites in a distributed mode to achieve real-time on-board resource allocation on demand.

APA, Harvard, Vancouver, ISO, and other styles

9

A., Wang, Lei L., Lagunas E., Isabel Pérez-Neira Ana, Chatzinotas S., and Ottersen B. "Joint Optimization of Beam-Hopping Design and NOMA-Assisted Transmission for Flexible Satellite Systems." IEEE Trans. Wireless Commun. 21, no. 12 (2022): 1. https://doi.org/10.1109/TWC.2022.3170435.

Full text

Abstract:

Next-generation satellite systems require more flexibility in resource management such that available radio resources can be dynamically allocated to meet time-varying and non-uniform traffic demands. Considering potential benefits of beam hopping (BH) and non-orthogonal multiple access (NOMA), we exploit the time-domain flexibility in multi-beam satellite systems by optimizing BH design, and enhance the power-domain flexibility via NOMA. In this paper, we investigate the synergy and mutual influence of beam hopping and NOMA. We jointly optimize power allocation, beam scheduling, and terminal-timeslot assignment to minimize the gap between requested traffic demand and offered capacity. In the solution development, we formally prove the NP-hardness of the optimization problem. Next, we develop a bounding scheme to tightly gauge the global optimum and propose a suboptimal algorithm to enable efficient resource assignment. Numerical results demonstrate the benefits of combining NOMA and BH, and validate the superiority of the proposed BH-NOMA schemes over benchmarks. Author

APA, Harvard, Vancouver, ISO, and other styles

10

Wang, Wenjin, Ao Liu, Qian Zhang, Li You, Xiqi Gao, and Gan Zheng. "Robust Multigroup Multicast Transmission for Frame-Based Multi-Beam Satellite Systems." IEEE Access 6 (2018): 46074–83. http://dx.doi.org/10.1109/access.2018.2865998.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

TSUKUDA, Eiichi, Yoichi KAWAKAMI, Shojiro MIYAKE, and Shigeki OGAWA. "On-board antenna pointing mechanism for multi-beam satellite communications systems." JSME international journal 30, no. 270 (1987): 2011–17. http://dx.doi.org/10.1299/jsme1987.30.2011.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Wang, Yingjie, Ming Zeng, and Zesong Fei. "Efficient Resource Allocation for Beam-Hopping-Based Multi-Satellite Communication Systems." Electronics 12, no. 11 (2023): 2441. http://dx.doi.org/10.3390/electronics12112441.

Full text

Abstract:

With the rapid growth of data traffic, low earth orbit (LEO) satellite communication networks have gradually ushered in a new trend of development due to its advantages of low latency, wide coverage, and high capacity. However, as a result of the limited on-board resources and rapidly changing traffic demand, it is increasingly urgent to design an efficient resource-allocation scheme to satisfy the traffic demand. In this paper, we propose two resource allocation algorithms in the multi-satellite system based on beam-hopping technology. In the offline case, it is assumed that the channel gains in all time-slots are known in advance, and we propose a heuristic algorithm to allocate time and frequency resources, and a successive convex approximation (SCA) algorithm to allocate power resources. In the online case, it is assumed that only the instant channel gains information is known; therefore, we apply the dynamic programming (DP) algorithm to maximize the system throughput. The simulation results prove that the proposed resource-allocation algorithms based on beam-hopping technology have better performance than the traditional average allocation method, and the online algorithm has acceptable performance loss compared with the offline algorithm.

APA, Harvard, Vancouver, ISO, and other styles

13

Wang, Heng, Aijun Liu, and Xiaofei Pan. "Optimization of Joint Power and Bandwidth Allocation in Multi-Spot-Beam Satellite Communication Systems." Mathematical Problems in Engineering 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/683604.

Full text

Abstract:

Multi-spot-beam technique has been widely applied in modern satellite communication systems. However, the satellite power and bandwidth resources in a multi-spot-beam satellite communication system are scarce and expensive; it is urgent to utilize the resources efficiently. To this end, dynamically allocating the power and bandwidth is an available way. This paper initially formulates the problem of resource joint allocation as a convex optimization problem, taking into account a compromise between the maximum total system capacity and the fairness among the spot beams. A joint bandwidth and power allocation iterative algorithm based on duality theory is then proposed to obtain the optimal solution of this optimization problem. Compared with the existing separate bandwidth or power optimal allocation algorithms, it is shown that the joint allocation algorithm improves both the total system capacity and the fairness among spot beams. Moreover, it is easy to be implemented in practice, as the computational complexity of the proposed algorithm is linear with the number of spot beams.

APA, Harvard, Vancouver, ISO, and other styles

14

Kai, Tao, Sun Xiaoyun, Wang Yang, and Jingchun Li. "System Modeling and Precoding Design for Multi-beam Dual-polarized Satellite MIMO System." Recent Patents on Engineering 13, no. 4 (2019): 374–81. http://dx.doi.org/10.2174/1872212112666181015150356.

Full text

Abstract:

Background: As the multimedia service develops and the transmission rate in terrestrial communication systems increases rapidly, satellite communication needs to improve the transmission rate and throughput. Multiple Input Multiple Output (MIMO) techniques can increase the system capacity significantly by introducing the space dimension, as the system bandwidth remains the same. Therefore, utilization of MIMO for satellite communications to increase the capacity is an important research topic. So MIMO techniques for multibeam satellite communications are researched in the dissertation. Objective: The goal of this work is improving the capacity of the satellite system. Multi-beam and dual-polarized technologies are applied to a satellite system to improve the capacity further. Methods: In this paper, we first introduce a multi-beam dual-polarized satellite multi-put and multiout (MBDP-S-MIMO) system which combines the full frequency multiplexing and dual-polarization technologies. Then the system model and channel model are first constructed. At last, to improve the capacity further, BD and BD-ZF precoding algorithms are applied to MBDP-S-MIMO and their performance is verified by simulation. Results: Simulation results show the performance of the BD precoding algorithm gets better with the growth of the XPD at the receiver and is almost not affected by the growth of the channel polarization correlation coefficient. In addition, with the growth of the users’ speed, the performance becomes worse. Conclusion: The multi-beam dual-polarized satellite MIMO system has high capacity, and it has certain application prospects for satellite communication.

APA, Harvard, Vancouver, ISO, and other styles

15

Angelis, Constantinos T. "Simulation analysis and performance of a feasible GNSS system with multi-beam antennas deployment operating in Galileo frequency bands." International Journal of Microwave and Wireless Technologies 4, no. 5 (2012): 537–43. http://dx.doi.org/10.1017/s1759078712000529.

Full text

Abstract:

New Global Navigation Satellite System (GNSS) systems under development, such as Galileo, are very promising for future global positioning-based applications. A vast research is undergoing a final stage of implementation in order to fulfill the primary purpose of European Space Agency for developing and then sustaining of 30 (27 + 3 spares) Galileo satellites in orbit. This article presents simulation results for a realistic deployment of multibeam antennas, with a new modified theoretical pattern, in GNSS Satellite Systems. The proposed multibeam antennas use 61-spot beams for maximum efficiency in terms of satellite coverage and accessing high quality of service. In order to prove the reliability and feasibility of this work, various simulations were conducted using the upcoming Galileo system as a platform taking into consideration real-world conditions. Gain analysis versus elevation, Bit Error Rate (BER) and access time simulation results show that the viability of the proposed multibeam antenna deployment is established.

APA, Harvard, Vancouver, ISO, and other styles

16

He, Chao, Zhi-dong Xie, Dong-ming Bian, and Xi-jian Zhong. "Study of interference localization using single satellite based on signal strength distribution in multi-beam antenna for satellite communications system." International Journal of Distributed Sensor Networks 14, no. 5 (2018): 155014771877401. http://dx.doi.org/10.1177/1550147718774015.

Full text

Abstract:

Large onboard antennas with multi-beams are used almost in all the Geostationary Earth Orbit satellite communications systems, which are always disturbed by jams and inferences. However, there are lots of factors restricting interference localization in satellite communications system because the system is not designed for location-oriented. This article makes use of the characteristic that each spot beam of multi-beams antenna has different gain at the position of interference, establishes the localization equations set by using the ground projection model of multi-beams antenna pattern, and gives two methods of solving equations. Thus, it proposes interference localization algorithm using single satellite, based on antenna gain and the distribution of signal strength in multi-beam space. Because of not depending on extra onboard equipments and other facilities, it has no effect on the construction and operation of satellite communications system. From the results of analyses and simulations, the localization precision can satisfy the general practical requirement. The algorithm could be used in checking the interference of the system, decision supporting of anti-jamming, and improving operation and management of the system.

APA, Harvard, Vancouver, ISO, and other styles

17

Hazer Inaltekin, Mark Bowyer, Iain B. Collings, Gunes Karabulut Kurt, Walid Saad, and Phil Whiting. "Future satellite communications: Satellite constellations and connectivity from space." ITU Journal on Future and Evolving Technologies 5, no. 2 (2024): 288–94. http://dx.doi.org/10.52953/pcds7523.

Full text

Abstract:

Satellite communications is currently undergoing a massive growth, with a rapid expansion in Low Earth Orbit (LEO) networks, and a range of new satellite technologies. Until very recently, satellite communication systems and terrestrial 5/6G wireless networks have been complementary distinct entities. There is now the opportunity to bring these networks together and deliver an integrated global coverage multi-service network. Achieving this will require solving some key research challenges, and leveraging new technologies including high frequency phased-array antennas, onboard processing, dynamic beam hopping, physical layer signal processing algorithms, transmission waveforms, and adaptive inter-satellite links and routing. By integrating seamlessly with terrestrial 5/6G networks and low altitude flying access points, future satellite networks promise to deliver universal connectivity on a global scale, overcoming geographical limitations. In this special issue, we focus on the future of satellite communications, exploring topics ranging from beam hopping and design to space routing and THz satellite communications. Our aim is to shed light on the potential of these emerging technologies and their role in reshaping the landscape of global connectivity.

APA, Harvard, Vancouver, ISO, and other styles

18

You, Li, Ao Liu, Wenjin Wang, and Xiqi Gao. "Outage Constrained Robust Multigroup Multicast Beamforming for Multi-Beam Satellite Communication Systems." IEEE Wireless Communications Letters 8, no. 2 (2019): 352–55. http://dx.doi.org/10.1109/lwc.2018.2872710.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Hejres, Jasem. "Web traffic capacity of multi-beam GEO and MEO mobile satellite systems." Electronics Letters 41, no. 3 (2005): 138. http://dx.doi.org/10.1049/el:20057297.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Ge, Xin, Gongliang Liu, Victor C. M. Leung, and Naitong Zhang. "A novel MAC protocol for IDMA-based multi-beam satellite communication systems." International Journal of Communication Systems 27, no. 12 (2013): 4038–58. http://dx.doi.org/10.1002/dac.2597.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Li, Cheng Mei, Jian Jun Wu, Xiao Ning Zhang, Xi Luan, and Hai Ge Xing. "Propagation Delay Difference Estimation for Initial Random Access in LTE Compatible Mobile Satellite Communications System." Advanced Materials Research 846-847 (November 2013): 647–50. http://dx.doi.org/10.4028/www.scientific.net/amr.846-847.647.

Full text

Abstract:

In this paper, a two-step propagation delay difference estimation method is proposed for LTE compatible multi-beam satellite systems to ensure the initial random access (RA). For GEO satellite system, there exists a large propagation delay difference, we cannot directly apply the LTE delay estimation method. To deal with this issue, we first divide a satellite beam into some layered small sub-areas according to the different delay difference values. Then, two types of Physical Random Access Channel (PRACH) preamble burst format are given. The detailed PRACH parameters are provided. Finally, simulations are performed and the results verify the availability of our proposed design.

APA, Harvard, Vancouver, ISO, and other styles

22

Chitambara Rao, Karedla, Dasari Nataraj, K. S. Chakradhar, et al. "An Integrated Dual Antenna for Multi-Band Satellite Communication Applications." Engineering, Technology & Applied Science Research 15, no. 3 (2025): 23707–13. https://doi.org/10.48084/etasr.10372.

Full text

Abstract:

Satellite communication applications for a variety of platforms are expanding quickly as the current technology and the demand for multi-band antennas are driving up. Multi-band antennas are likely to be required for the majority of communication systems including commercial, amateur, and military ones. For military communications, various antennas are employed on a mast to cover different bands, particularly the multifunction mast-mounted antennas that are based on submarines. However, there will be limited space on the mast in case different antennas are used for different frequencies, a limitation which will restrict the ability of the submarine-based multifunction mast-mounted antenna to cover the different bands. Thus, instead of employing different antennas for different bands, a multi-band antenna can be used to compensate for the space limitation. Modern submarines should also be able to communicate with satellites. Designing an antenna for satellite communication is difficult because successful operation necessitates specific characteristics, such as low axial ratio, low Voltage Standing Wave Ratio (VSWR), high gain, high band width, and high 3 dB beam width. This work proposes an inventive design approach for an integrated dual antenna on a single ground for two bands, the L-Band and S-Band. The latter cover the five satellite communication applications, including sending (2500-2520 MHz) and receiving (2670-2690 MHz) bands of S-Band satellite communication, the Global Positioning System (GPS)-1575.42 MHz, the Global Navigational Satellite System (GNSS)-1610 MHz, and the Indian Regional Navigational Satellite System (IRNSS)-1176.5 MHz. To examine important characteristics, including VSWR, gain, axial ratio, and 3 dB beam width, a simulation of an integrated dual antenna is constructed. The parameters are examined after the simulation in order to assess the proposed antenna's performance. The analysis results indicate that the proposed antenna is suitable for a variety of satellite communication applications, and highly suitable for both the L-Band and S-Band.

APA, Harvard, Vancouver, ISO, and other styles

23

Chu, Dapeng, Yong Mao, Haoxiang Li, Hong Bie, and Yongjin Zhou. "Dual-Polarized Multi-Beam Fixed-Frequency Beam Scanning Leaky-Wave Antenna." Sensors 23, no. 11 (2023): 5070. http://dx.doi.org/10.3390/s23115070.

Full text

Abstract:

A fixed-frequency beam-scanning leaky-wave antenna (LWA) array with three switchable dual-polarized beams is proposed and experimentally demonstrated. The proposed LWA array consists of three groups of spoof surface plasmon polaritons (SPPs) LWAs with different modulation period lengths and a control circuit. Each group of SPPs LWAs can independently control the beam steering at a fixed frequency by loading varactor diodes. The proposed antenna can be configured in both multi-beam mode and single-beam mode, where the multi-beam mode with optional two or three dual-polarized beams. The beam width can be flexibly adjusted from narrow to wide by switching between multi-beam and single-beam states. The prototype of the proposed LWA array is fabricated and measured, and both simulation and experimental results show that the antenna can accomplish a fixed frequency beam scanning at an operating frequency of 3.3 to 3.8 GHz with a maximum scanning range of about 35° in multi-beam mode and about 55° in single-beam mode. It could be a promising candidate for application in the space–air–ground integrated network scenario in satellite communication and future 6G communication systems.

APA, Harvard, Vancouver, ISO, and other styles

24

Lee, Kyu-Hwan, and Jae-Hyun Kim. "Multi-way relay system with network coding in multi-spot beam satellite networks." Wireless Networks 23, no. 1 (2015): 205–17. http://dx.doi.org/10.1007/s11276-015-1147-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Yan, Yan, Weiwei Yang, Bangning Zhang, Daoxing Guo, and Guoru Ding. "Outage Constrained Robust Beamforming for Sum Rate Maximization in Multi-Beam Satellite Systems." IEEE Communications Letters 24, no. 1 (2020): 164–68. http://dx.doi.org/10.1109/lcomm.2019.2952770.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Kapsis, Theodore T., Nikolaos K. Lyras, and Athanasios D. Panagopoulos. "Optimal Power Allocation in Optical GEO Satellite Downlinks Using Model-Free Deep Learning Algorithms." Electronics 13, no. 3 (2024): 647. http://dx.doi.org/10.3390/electronics13030647.

Full text

Abstract:

Geostationary (GEO) satellites are employed in optical frequencies for a variety of satellite services providing wide coverage and connectivity. Multi-beam GEO high-throughput satellites offer Gbps broadband rates and, jointly with low-Earth-orbit mega-constellations, are anticipated to enable a large-scale free-space optical (FSO) network. In this paper, a power allocation methodology based on deep reinforcement learning (DRL) is proposed for optical satellite systems disregarding any channel statistics knowledge requirements. An all-FSO, multi-aperture GEO-to-ground system is considered and an ergodic capacity optimization problem for the downlink is formulated with transmitted power constraints. A power allocation algorithm was developed, aided by a deep neural network (DNN) which is fed channel state information (CSI) observations and trained in a parameterized on-policy manner through a stochastic policy gradient approach. The proposed method does not require the channels’ transition models or fading distributions. To validate and test the proposed allocation scheme, experimental measurements from the European Space Agency’s ARTEMIS optical satellite campaign were utilized. It is demonstrated that the predicted average capacity greatly exceeds other baseline heuristic algorithms while strongly converging to the supervised, unparameterized approach. The predicted average channel powers differ only by 0.1 W from the reference ones, while the baselines differ significantly more, about 0.1–0.5 W.

APA, Harvard, Vancouver, ISO, and other styles

27

Dong, Zanyang, Longteng Yi, Pengfei Qin, Yejun Zhou, Cheng Zhang, and Kang Liu. "Quantification and Analysis of Carrier-to-Interference Ratio in High-Throughput Satellite Systems." Electronics 12, no. 16 (2023): 3443. http://dx.doi.org/10.3390/electronics12163443.

Full text

Abstract:

Recently, the demand for high data traffic transmission is experiencing unstoppable growth, and multi-beam high-throughput satellite (HTS) systems have proven to be effective solutions. However, how to manage and eliminate the co-channel interference caused by frequency reuse in multi-beam HTS systems is still a challenging issue. Motivated by this background, this paper begins with discussing the interference mechanism in the uplink and downlink of HTS systems and then uses the quantification method of carrier-to-interference ratio (CIR), whereby the influencing factors of the CIR are accordingly analyzed. In addition, the common CIR selection strategies are summarized and compared with each other in terms of their advantages and disadvantages. Based on the proposed CIR quantification and statistical selection methods, two frequency plan cases are simulated for the scenario of 19 beams with 4-color reuse. The results show that the proposed quantification and selection methods are rather practical and offer a feasible approach for frequency plan adjustment based on CIR optimization. Finally, a simulation analysis of the CIR under different power spectral density (PSD) values is conducted, and the results show that the PSD has a substantial impact on the CIR.

APA, Harvard, Vancouver, ISO, and other styles

28

Zhang, Rui, Yuhan Ruan, Yongzhao Li, and Can Liu. "Interference-Aware Radio Resource Management for Cognitive High-Throughput Satellite Systems." Sensors 20, no. 1 (2019): 197. http://dx.doi.org/10.3390/s20010197.

Full text

Abstract:

By providing interactive broadband services to geographical areas underserved by terrestrial infrastructure, multi-beam satellite systems play a central role in future wireless communications. Targeting the terabit throughput requirements in satellite communications, we introduce a cognitive radio-based high-throughput satellite (HTS) system architecture where full frequency reuse is employed among beams. Moreover, by analyzing the characteristics of the considered architecture, we discuss the design challenges of radio resource management in cognitive HTS systems exposed to both intra-system and inter-system co-channel interference. Furthermore, to combat interference with low overhead, we propose a generic interference-aware resource management framework based on joint spatial division and multiplexing (JSDM). Under this framework, user grouping along with two-stage precoding is studied to achieve substantial improvement in the overall system throughput. Finally, some future research directions and challenges are also given.

APA, Harvard, Vancouver, ISO, and other styles

29

Hongyi Fu, Guoan Bi, and K. Arichandran. "Performance of multi-beam CDMA-based LEO satellite systems in a Rice-lognormal channel." IEEE Communications Letters 3, no. 4 (1999): 88–90. http://dx.doi.org/10.1109/4234.757197.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Sakai, T., K. Kobayashi, S. Kubota, M. Morikura, and S. Kato. "Soft-decision Viterbi decoding with diversity combining for multi-beam mobile satellite communication systems." IEEE Journal on Selected Areas in Communications 13, no. 2 (1995): 285–90. http://dx.doi.org/10.1109/49.345872.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Wang, Haiming, Zhuming Deng, Xiqi Gao, and Xiaohu You. "Optimization and efficient detection of primary synchronization signal for multi-beam satellite-LTE systems." International Journal of Satellite Communications and Networking 34, no. 2 (2015): 115–29. http://dx.doi.org/10.1002/sat.1102.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Lin, Yujie, Chunyuan Hu, Zhengyuan Shi, Bizheng Liang, and Jianguo Li. "Low-Complexity Online Calibration for Large-Scale Multi-Beam Antennas." Electronics 12, no. 7 (2023): 1690. http://dx.doi.org/10.3390/electronics12071690.

Full text

Abstract:

High-throughput satellite communication based on large-scale multi-beam antennas is a promising technology for sixth-generation (6G) mobile networks. Conventional online calibration methods for large-scale antennas after satellite launch are restricted by communication signals. This paper proposes an online calibration method of amplitude and phase errors without disturbing the normal communication traffic. Two important aspects of calibration are discussed, i.e., closed-form expressions of calibration accuracy and hardware complexity. Simulation results show that theoretical approximation results are close to simulation results when the number of antennas is less than half of the code length. The relative amplitude and phase performance deteriorate by 6.12 dB and 40.96 deg, respectively, when the power is lower than the reference 20 dB. Finally, a calibration experimental system with eight beams is built for verification.

APA, Harvard, Vancouver, ISO, and other styles

33

HUSSEIN, GAMAL A., MOSTAFA A. NOFAL, MOAWAD I. DESSOUKY, et al. "SUPPORTING DISTRESS SIGNALS OVER LOW EARTH ORBIT MOBILE SATELLITE SYSTEMS FOR EMERGENCY INFORMATION ACQUISITION." International Journal of Information Acquisition 09, no. 03n04 (2013): 1350018. http://dx.doi.org/10.1142/s0219878913500186.

Full text

Abstract:

Low earth orbit (LEO) satellite systems allow a broad range of services to be provided using small, lightweight, cellular-like portable telephones. Exploiting LEO satellites to support distress signals for aircrafts, ships and international travelers is explored in the current paper. A multi-service priority-oriented algorithm is proposed for handling voice, data and emergency signals over LEO satellites. The emergency signal is privileged with service priority so that rescue operation can be carried out as soon as possible. The priority mechanism includes channel reservation as well as joining a queue if no free channel is available as long as the request is roaming in the handover area. In addition, a simplified but efficient approach is suggested for locating the object of an imminent danger situation. As LEO satellites are non-geostationary, the visible period of each spot-beam is small. Consequently, a teletraffic model, that accommodates the mobility of spot-beams as well as the resulting handover rate, is developed in order to gauge the performance of the proposed algorithm. Numerical results for access denying and service-dropping rates are presented for nominal system parameters.

APA, Harvard, Vancouver, ISO, and other styles

34

Onrubia, Raul, Daniel Pascual, Jorge Querol, Hyuk Park, and Adriano Camps. "The Global Navigation Satellite Systems Reflectometry (GNSS-R) Microwave Interferometric Reflectometer: Hardware, Calibration, and Validation Experiments." Sensors 19, no. 5 (2019): 1019. http://dx.doi.org/10.3390/s19051019.

Full text

Abstract:

This manuscript describes the Microwave Interferometric Reflectometer (MIR) instrument, a multi-beam dual-band GNSS-Reflectometer with beam-steering capabilities built to assess the performance of a PAssive Reflectrometry and Interferometry System—In Orbit Demonstrator (PARIS-IoD) like instrument and to compare the performance of different GNSS-R techniques and signals. The instrument is capable of tracking up to 4 different GNSS satellites, two at L1/E1 band, and two at L5/E5 band. The calibration procedure of the up- and down-looking arrays is presented, the calibration performance is evaluated, and the results of the validation experiments carried out before the field experiments are shown in this paper.

APA, Harvard, Vancouver, ISO, and other styles

35

Jakoby, Rolf, Alexander Gaebler, and Christian Weickhmann. "Microwave Liquid Crystal Enabling Technology for Electronically Steerable Antennas in SATCOM and 5G Millimeter-Wave Systems." Crystals 10, no. 6 (2020): 514. http://dx.doi.org/10.3390/cryst10060514.

Full text

Abstract:

Future satellite platforms and 5G millimeter wave systems require Electronically Steerable Antennas (ESAs), which can be enabled by Microwave Liquid Crystal (MLC) technology. This paper reviews some fundamentals and the progress of microwave LCs concerning its performance metric, and it also reviews the MLC technology to deploy phase shifters in different topologies, starting from well-known toward innovative concepts with the newest results. Two of these phase shifter topologies are dedicated for implementation in array antennas: (1) wideband, high-performance metallic waveguide phase shifters to plug into a waveguide horn array for a relay satellite in geostationary orbit to track low Earth orbit satellites with maximum phase change rates of 5.1°/s to 45.4°/s, depending on the applied voltages, and (2) low-profile planar delay-line phase shifter stacks with very thin integrated MLC varactors for fast tuning, which are assembled into a multi-stack, flat-panel, beam-steering phased array, being able to scan the beam from −60° to +60° in about 10 ms. The loaded-line phase shifters have an insertion loss of about 3 dB at 30 GHz for a 400° differential phase shift and a figure-of-merit (FoM) > 120°/dB over a bandwidth of about 2.5 GHz. The critical switch-off response time to change the orientation of the microwave LCs from parallel to perpendicular with respect to the RF field (worst case), which corresponds to the time for 90 to 10% decay in the differential phase shift, is in the range of 30 ms for a LC layer height of about 4 µm. These MLC phase shifter stacks are fabricated in a standard Liquid Crystal Display (LCD) process for manufacturing low-cost large-scale ESAs, featuring single- and multiple-beam steering with very low power consumption, high linearity, and high power-handling capability. With a modular concept and hybrid analog/digital architecture, these smart antennas are flexible in size to meet the specific requirements for operating in satellite ground and user terminals, but also in 5G mm-wave systems.

APA, Harvard, Vancouver, ISO, and other styles

36

Zhang, Chen, Jiangtao Yang, Yong Zhang, Ziwei Liu, and Gengxin Zhang. "Dynamic Beam Hopping Time Slots Allocation Based on Genetic Algorithm of Satellite Communication under Time-Varying Rain Attenuation." Electronics 10, no. 23 (2021): 2909. http://dx.doi.org/10.3390/electronics10232909.

Full text

Abstract:

Beam hopping technology is considered to provide a high level of flexible resource allocation to manage uneven traffic requests in multi-beam high throughput satellite systems. Conventional beam hopping resource allocation methods assume constant rainfall attenuation. Different from conventional methods, by employing genetic algorithm this paper studies dynamic beam hopping time slots allocation under the effect of time-varying rain attenuation. Firstly, a beam hopping system model as well as rain attenuation time series based on Dirac lognormal distribution are provided. On this basis, the dynamic allocation method by employing genetic algorithm is proposed to obtain both quantity and arrangement of time slots allocated for each beam. Simulation results show that, compared with conventional methods, the proposed algorithm can dynamically adjust time slots allocation to meet the non-uniform traffic requirements of each beam under the effect of time-varying rain attenuation and effectively improve system performance.

APA, Harvard, Vancouver, ISO, and other styles

37

Takahashi, Masaki, Yuichi Kawamoto, Nei Kato, Amane Miura, and Morio Toyoshima. "Adaptive Power Resource Allocation With Multi-Beam Directivity Control in High-Throughput Satellite Communication Systems." IEEE Wireless Communications Letters 8, no. 4 (2019): 1248–51. http://dx.doi.org/10.1109/lwc.2019.2912753.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Fu, Hongyi, Guoan Bi, and K. Arichandran. "Effect of multiple access interference on performance of multi-beam CDMA-based LEO satellite systems." Electronics Letters 34, no. 2 (1998): 149. http://dx.doi.org/10.1049/el:19980178.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

He, YuanZhi, YiZhen Jia, and XuDong Zhong. "A traffic-awareness dynamic resource allocation scheme based on multi-objective optimization in multi-beam mobile satellite communication systems." International Journal of Distributed Sensor Networks 13, no. 8 (2017): 155014771772355. http://dx.doi.org/10.1177/1550147717723554.

Full text

Abstract:

Mobile satellite communication systems play an important role in space information networks. They mostly operate at the L or S band and have multiple beams efficiently reusing the limited spectrum. Advanced technologies, such as beamforming, are used to generate numerous beams through multiple feeders, and each beam’s power allocation is correlated and constrained. Frequency reuse among multiple beams results in co-channel interference issue, which makes bandwidth allocation among multiple beams coupled. It is a challenging topic to optimize the resource allocation in the real-time service traffic. In this article, a new multi-objective programming scheme is used to solve the dynamic resource allocation problem, guaranteeing high quality-of-service for multiple services of different priorities. Since the dynamic resource allocation problem is formulated as NP-hard, a new traffic-aware dynamic resource allocation (TADRA) algorithm is proposed. This algorithm is proved to be optimal in terms of the Pareto-front under constraints of co-channel interference and onboard transmit power. Simulation results show that the trade-off is well balanced between the call completion ratio in high priority and the throughput for video and data services in medium and low priorities. Additionally, it is shown that the new multi-objective programming scheme, based on the traffic-awareness dynamic resource allocation algorithm, can rapidly achieve the Pareto-front solutions and reduce the computing complexity to a large extent.

APA, Harvard, Vancouver, ISO, and other styles

40

Boulos, Federico, Georg Frederik Riemschneider, and Stefano Caizzone. "3D Phased Array Enabling Extended Field of View in Mobile Satcom Applications." Electronics 13, no. 2 (2024): 310. http://dx.doi.org/10.3390/electronics13020310.

Full text

Abstract:

Satellite communication (satcom) is experiencing increased interest to cover the connectivity gaps of terrestrial networks. To ensure high performance and throughput for the user—and even more so in Communications-On-The-Move(COTM) systems, e.g., in aeronautics—steerable antennas such as phased arrays are required to adjust the beam so as to follow the satellite’s trajectory. The mutual movement of terminals and satellite in COTM systems calls for a broad Field of View (FoV) and, hence, poses a challenge to common planar systems. For improving the FoV, common solutions require ad hoc designs, such as multi-mode antennas, wide half-power-beamwidth antennas or metasurfaces. By contrast, 3D arrays are able to cover a wider angular region by the 3D allocation of the antennas. In this paper, the benefits and drawbacks of moving from 2D (planar) arrays to 3D phased arrays are investigated. Multiple geometrical configurations are analyzed, keeping in mind the size requirements of aeronautic terminals. The best configuration is, hence, an array capable of enhancing the FoV of the terminal. The proposed antenna architecture offers a good trade-off between design complexity and performance, and it could be further developed to become an aeronautic-grade terminal aperture.

APA, Harvard, Vancouver, ISO, and other styles

41

Bejarano, Juan-Manuel Rodriguez, Carlos Miguel Nieto, and Francisco Javier Ruiz Pinar. "MF-TDMA Scheduling Algorithm for Multi-Spot Beam Satellite Systems Based on Co-Channel Interference Evaluation." IEEE Access 7 (2019): 4391–99. http://dx.doi.org/10.1109/access.2018.2887167.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Gonzalez, Manuel J., Ana Ruiz, Alberto Pellon, et al. "Enabling In-Flight Connectivity with the new Generation of Electronically Steered Antennas." IOP Conference Series: Materials Science and Engineering 1226, no. 1 (2022): 012109. http://dx.doi.org/10.1088/1757-899x/1226/1/012109.

Full text

Abstract:

Abstract In-flight communication (IFC) services offered to passengers and crew are of great importance to the air transport sector. The improvement of the satellite capacity with High Throughput Satellites (HTS) in GEO and the advent of MEO and LEO constellations will support the forecast growth of the IFC market. Antenna equipment for satellite communications will need to address multiple scenarios from G2G (Gate-to-Gate) to multi-operation under GEO-MEO-LEO systems. Under these conditions, antennas with the ability to track multiple satellites and having superior performance and reliability will play a key role. Electronically steered antennas (ESA) have emerged as a viable solution in response to these demands. The EU-funded LESAF project proposes an ESA solution of reduced size and greater efficiency for the next generation of in-flight connectivity services. This will be managed through the requirements definition, system analysis, technology assessment, prototyping and validation of ESAs. The project has successfully passed the first milestone corresponding to requirements consolidation, baseline architecture definition and candidate technology trade-offs. Multi-beam Electronically Steered Antennas, separated apertures for both transmission and reception, a flexible modular approach coupled with planar multilayer integration and an advanced beamformer design are the basis for the proposed concept. The following project phase will be focused on the design and validation of an antenna demonstrator aimed at proving the superior added value of ESAs technological solution for the aviation industry needs.

APA, Harvard, Vancouver, ISO, and other styles

43

Panthi, Sunil, and Ahmed M. Eltawil. "Dynamic Resource Management in High Throughput Satellite with Multi Port Amplifier (MPA)." International Journal of Interdisciplinary Telecommunications and Networking 8, no. 3 (2016): 66–81. http://dx.doi.org/10.4018/ijitn.2016070105.

Full text

Abstract:

The demand for data capacity has been growing, especially in the aviation and maritime industries and is expected to continue to grow in the foreseeable future. The satellite industry is moving to High Throughput Satellite (HTS) that are characterized by large numbers of small spot beams, frequency reuse, higher Equivalent Isotropically Radiated Power (EIRP) and higher Gain to Noise Temperature (G/T) to meet growing capacity demand. Multi-Port Amplifiers (MPA) increase the flexibility of HTS systems by allowing capacity to be allocated dynamically based on changing demand. This will allow capacity requirements to be planned based on the sum of the requirements across all beams rather than the peaks in each HTS beam. The authors propose a ground based solution that will maximize resource utilization of an HTS with an MPA and deliver the capacity dynamically based on demand. Maritime, commercial aviation, satellite based cellular backhaul, and disaster recovery services are the main applications that can benefit from the solution they propose. The authors' results show significant reduction in the overall capacity requirements because of the more efficient utilization of the satellite resources.

APA, Harvard, Vancouver, ISO, and other styles

44

Hu, Xin, Yuchen Zhang, Xianglai Liao, Zhijun Liu, Weidong Wang, and Fadhel M. Ghannouchi. "Dynamic Beam Hopping Method Based on Multi-Objective Deep Reinforcement Learning for Next Generation Satellite Broadband Systems." IEEE Transactions on Broadcasting 66, no. 3 (2020): 630–46. http://dx.doi.org/10.1109/tbc.2019.2960940.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Matsui, H., M. Nakamura, T. Mukai, K. Tsuruda, and H. Hayakawa. "Observations of convection in the dayside magnetosphere by the beam instrument on Geotail." Annales Geophysicae 19, no. 3 (2001): 303–10. http://dx.doi.org/10.5194/angeo-19-303-2001.

Full text

Abstract:

Abstract. We report observations of magnetospheric convection by the beam instrument, EFD-B, on Geotail. The region analyzed in this study is mainly the afternoon sector of the magnetosphere between L = 9.7 - 11.5. When the instrument is operated, electron beams are emitted from guns and some of them return to detectors attached to the main body of the satellite. However, we find that the return beams are often spread over a wide range of satellite spin phase angles, so that the calculated convection is unreliable. In order to remove noisy data, we set up suitable selection criteria. We infer that the convection strength is of the order of 20 km/s. The convection has generally westward and outward components. This indicates that the plasma located at the satellite positions is being convected toward the magnetopause. Moreover, the obtained convection is highly variable because standard deviations are comparable to the strength. We then compare the convection estimated by the beam instrument with that by the particle instrument, LEP. We find that the convections derived from the two instruments are positively correlated, with correlation coefficients above 0.7. The analysis reported here is expected to be useful in the interpretation of the multi-spacecraft data from the Cluster II mission.Key words. Magnetospheric physics (current systems; electric fields; instruments and techniques)

APA, Harvard, Vancouver, ISO, and other styles

46

krishna, Mr P. V. Murali, and Lade Surendra Babu. "HYBRID BEAMFORMING FOR MULTIBEAM PHASED ARRAY RECEVIERS." INTERANTIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENGINEERING AND MANAGEMENT 07, no. 12 (2023): 1–3. http://dx.doi.org/10.55041/ijsrem27817.

Full text

Abstract:

In the search for enhanced wireless communication systems, multibeam phased array receivers have gained prominence. They promise to significantly boost data rates, reduce latency, and improve reliability. However, implementing multibeam receivers with traditional beamforming techniques can be challenging due to the high computational demands and the need for multiple radio frequency (RF) chains. Hybrid beamforming combines the advantages of digital and analog beamforming to strike a balance between performance and complexity. Our research delves into the following aspects of Hybrid beamforming for multibeam phased array receivers: Reduced Hardware Complexity: By blending digital and analog beamforming, we reduce the number of required RF chains, making multibeam receivers more cost-effective. Enhanced Beam Steering: Hybrid beamforming maintains precise control over multiple beams, ensuring efficient signal reception and transmission. Real-World Applications: We discuss practical applications in 5G and beyond, satellite communications, and radar systems. The paper delves into the fundamental concepts of analog and digital beamforming, illustrating their respective strengths and limitations. It then presents the architecture of hybrid beamforming systems, emphasizing the synergistic integration of analog and digital components. Special attention is given to the design considerations of beamforming networks, antenna arrays, and the beam steering mechanism. KEYWORDS Hybrid Beamforming , Phased Array , Multi-Beam , Analog Beamforming , Digital Beamforming , Beamforming Networks , Antenna Array , Beam Steering , Spatial Multiplexing , Precoding , Channel Estimation , Interference Mitigation , Power Consumption , Millimeter Wave (mmWave) , 5G and Beyond .

APA, Harvard, Vancouver, ISO, and other styles

47

Reiche, Enrico, and Michael Schneider. "Challenges in the EM-based design of modern telecommunication satellite antennas." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 37, no. 4 (2018): 1461–80. http://dx.doi.org/10.1108/compel-09-2017-0378.

Full text

Abstract:

Purpose This paper aims to introduce design challenges of modern telecommunication satellite antennas. The antenna farms accommodated on a satellite are systems of high complexity. From the radio frequency (RF) point of view, the most important design issues, e.g. high power applications in space (vacuum) or typical antenna scenarios (single/multi beam antennas), and their solution are considered. Design/methodology/approach The paper presents the application of electro-magnetic (EM) field simulation in the design and optimisation process. The design of a telecommunications satellite antenna splits into several areas, for which different types of EM field solvers are used. Findings The use of EM field solvers enables an accurate and efficient design approach of modern geostationary telecommunications satellite antennas. Due to the use of EM field solvers, an excellent agreement between predictions and measurement results on feed as well as antenna system level is achieved. Originality/value This paper gives an overview of state-of-the-art telecommunications satellite antenna architectures and their efficient RF design due to the use of EM field solvers. Typical high power effects and other design issues are explained. RF engineers are encouraged to work on this exciting topic to further improve the design process and to develop new satellite antenna and feed products.

APA, Harvard, Vancouver, ISO, and other styles

48

Sun, Yixuan, Yueqiang Sun, Junming Xia, et al. "First In-Orbit Validation of Interferometric GNSS-R Altimetry: Mission Overview and Initial Results." Remote Sensing 17, no. 11 (2025): 1820. https://doi.org/10.3390/rs17111820.

Full text

Abstract:

Sea surface height (SSH) serves as a fundamental geophysical parameter in oceanographic research. In 2023, China successfully launched the world’s first spaceborne interferometric GNSS-R (iGNSS-R) altimeter, which features dual-frequency multi-beam scanning, interferometric processing, and compatibility with three major satellite navigation systems: the BeiDou Navigation Satellite System (BDS), the Global Positioning System (GPS), and the Galileo Satellite Navigation System (GAL). This launch marked the first in-orbit validation of the iGNSS-R altimetry technology. This study provides a detailed overview of the iGNSS-R payload design and analyzes its dual-frequency delay mapping (DM) measurements. We developed a refined DM waveform-matching algorithm that precisely extracts the propagation delays between reflected and direct GNSS signals, enabling the retrieval of global sea surface height (SSH) through the interferometric altimetry model. For validation, we employed an inter-satellite crossover approach using Jason-3 and Sentinel-6 radar altimetry as references, achieving an unprecedented SSH accuracy of 17.2 cm at a 40 km resolution. This represents a breakthrough improvement over previous GNSS-R altimetry efforts. The successful demonstration of iGNSS-R technology opens up new possibilities for cost-effective, wide-swath sea level monitoring. It showcases the potential of GNSS-R technology to complement existing ocean observation systems and enhance our understanding of global sea surface dynamics.

APA, Harvard, Vancouver, ISO, and other styles

49

Hurtado-Pérez, Arturo Benjamín, Abraham de Jesús Pablo-Sotelo, Fabián Ramírez-López, Jorge Javier Hernández-Gómez, and Miguel Felix Mata-Rivera. "On Topology Optimisation Methods and Additive Manufacture for Satellite Structures: A Review." Aerospace 10, no. 12 (2023): 1025. http://dx.doi.org/10.3390/aerospace10121025.

Full text

Abstract:

Launching satellites into the Earth’s orbit is a critical area of research, and very demanding satellite services increase exponentially as modern society takes shape. At the same time, the costs of developing and launching satellite missions with shorter development times increase the requirements of novel approaches in the several engineering areas required to build, test, launch, and operate satellites in the Earth’s orbit, as well as in orbits around other celestial bodies. One area with the potential to save launching costs is that of the structural integrity of satellites, particularly in the launching phase where the largest vibrations due to the rocket motion and subsequent stresses could impact the survival ability of the satellite. To address this problem, two important areas of engineering join together to provide novel, complete, and competitive solutions: topology optimisation methods and additive manufacturing. On one side, topology optimisation methods are mathematical methods that allow iteratively optimising structures (usually by decreasing mass) while improving some structural properties depending on the application (load capacity, for instance), through the maximisation or minimisation of a uni- or multi-objective function and multiple types of algorithms. This area has been widely active in general for the last 30 years and has two main core types of algorithms: continuum methods that modify continuous parameters such as density, and discrete methods that work by adding and deleting material elements in a meshing context. On the other side, additive manufacturing techniques are more recent manufacturing processes aimed at revolutionising manufacturing and supply chains. The main exponents of additive manufacturing are Selective Laser Melting (SLM) (3D printing) as well as Electron Beam Melting (EBM). Recent trends show that topology-optimised structures built with novel materials through additive manufacturing processes may provide cheaper state-of-the-art structures that are fully optimised to better perform in the outer-space environment, particularly as part of the structure subsystem of novel satellite systems. This work aims to present an extended review of the main methods of structural topology optimisation as well as additive manufacture in the aerospace field, with a particular focus on satellite structures, which may set the arena for the development of future satellite structures in the next five to ten years.

APA, Harvard, Vancouver, ISO, and other styles

50

Liu, Jann-Yenq, Chi-Yen Lin, Yu-Lin Tsai, et al. "Ionospheric GNSS Total Electron Content for Tsunami Warning." Journal of Earthquake and Tsunami 13, no. 05n06 (2019): 1941007. http://dx.doi.org/10.1142/s1793431119410070.

Full text

Abstract:

Tsunami waves can induce tsunami traveling ionospheric disturbances (TTIDs) of the total electron content (TEC). In this study, we examine the TEC derived by ground-based receivers of the global positioning system (GPS) and identify TTIDs induced by 2004 Indian Ocean tsunami. Simulations of the COMCOT (Cornell multi-grid coupled tsunami) model and analyses of the circle method, the ray-tracing technique, and the beam-forming technique are used to show that TTIDs can be quickly detected and confirmed after the tsunami occurrence. Finally, the ionospheric TEC derived by existing ground-based GNSS (Global Navigation Satellite Systems) receiving stations is demonstrated to be useful to support the tsunami early warning system.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Multi-beam satellite systems'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles