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Unlicensed Spectrum Sharing Game Between LEO Satellites and Terrestrial Cognitive Radio Networks

Chinese Journal of Aeronautics 2012年第4期25卷 605-614页

作者： XIE Zhuochen MA LU liang xuwen Shanghai Engineering Center for Micro-satellites Shanghai 200050China Shanghai Institute of Microsystem and Information Technology Chinese Academy of SciencesShanghai 200050China Graduate University of Chinese Academy of Sciences Beijing 100049China

By cognitive radio,the low Earth orbit（LEO） satellites may prefer to operate in the unlicensed spectrum which is open to all the users,and compete for the limited resources with terrestrial cognitive radio networks（CRNs）.The competition can be regarded as a game and analyzed with game *** particular unlicensed spectrum sharing problem is modeled here,and the special properties of ＂spatially-distinguished-interference＂ and the short period of the interactions between satellites and terrestrial CRNs are ***,the problem is formulated as a ＂partially-blind＂ finitely repeated prisoner＇s dilemma by game ***,we begin with two promising spectrum sharing schemes,which can be used to enforce the frequency reuse among the remotely located terrestrial CRN players as well as to overcome the observation *** analysis and comparison,it is proposed that the novel refreshing-contrite-tit-for-tat（R-CTFT） is the optimal spectrum sharing *** results verify that it can be used to utilize the spectrum most efficiently.

关键词： satellite communication systems cognitive radio unlicensed spectrum sharing spatially-distinguished-interference finitely repeated prisoner＇s dilemma partially-blind refreshing-contrite-tit-for-tat

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A distributed routing algorithm based-on simplified topology in LEO satellite networks

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High Technology Letters 2010年第2期16卷 117-123页

作者：曾媛 liang xuwen Li Yong Shanghai Engineering Center for Micro-Satellites Shanghai 200050 P.R. China Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 P.R. China

In this paper, a distributed muting strategy based on simplified topology （DRBST） was proposed for LEO satellite networks. The topology of LEO satellite networks was simplified aiming at minimizing intersatellite links handover number. To optimize the route based on the simplified topology, we considered not only the transmission delay but also the queuing delay and the processing delay, which were analyzed using Markov chain and determined using a novel methodology. The DRBST algorithm was simulated in a LEO satellite networks model built using OPNET. The simulation results demonstrate that the low complexity DRBST algorithm can guarantee end-to-end delay bound. Moreover, the muting protocol cost is much less than traditional algorithms.

关键词： LEO satellite networks distributed muting strategy based on simplified topology （DRBST） inter-satellite links handover OPNET simulation delay complexity

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Orbital reference frame estimation with power spectral density constraints for drag-free satellites

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Chinese Journal of Aeronautics 2016年第6期29卷 1721-1729页

作者： Zhang Yonghe Wang Yamin Mao Qingyun liang xuwen Shanghai Institute of Microsystem and Information Technology Chinese Academy of SciencesShanghai 200050China Shanghai Engineering Centre for Microsatellites Shanghai 201210China Joint Key Laboratory of Microsatellite Chinese Academy of SciencesShanghai 201210China

The drag-free satellites are widely used in the field of fundamental science as they enable the high-precision measurement in pure gravity fields. This paper investigates the estimation of local orbital reference frame(LORF) for drag-free satellites. An approach, taking account of the combination of the minimum estimation error and power spectral density(PSD) constraint in frequency domain, is proposed. Firstly, the relationship between eigenvalues of estimator and transfer function is built to analyze the suppression and amplification effect on input signals and obtain the eigenvalue range. Secondly, an optimization model for state estimator design with minimum estimation error in time domain and PSD constraint in frequency domain is established. It is solved by the sequential quadratic programming(SQP) algorithm. Finally, the orbital reference frame estimation of low-earth-orbit satellite is taken as an example, and the estimator of minimum variance with PSD constraint is designed and analyzed using the method proposed in this paper.

关键词： Drag-free satellite Orbital reference frame Power spectral density State estimation Transfer function

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Dynamic Channel Reservation Strategy Based on DQN Algorithm for Multi-Service LEO Satellite Communication System

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IEEE WIRELESS COMMUNICATIONS LETTERS 2021年第4期10卷 770-774页

作者： Li, Zongwang Xie, Zhuochen liang, xuwen Chinese Acad Sci Shanghai Engn Ctr Microsatellites Shanghai 201210 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

In this letter, a dynamic channel reservation (DCR) strategy based on deep Q network (DQN) is proposed for multi-service low earth orbit (LEO) satellite communication system. We develop a novel modeling method to represent DCR problem of multiple services as a reinforcement learning (RL) task. Based on this model, we calculate the influence of current channel allocation results on future environment and take it as one of the factors for channel allocation decision. Moreover, a corresponding neural network is designed as a decision evaluator to provide an end to end mapping of decision to its value, which effectively avoids the influence of artificial preconditions. Simulation results show that the proposed strategy can improve the overall quality of service (QOS) of the system.

关键词： Satellites Bandwidth Handover Low earth orbit satellites Channel allocation Resource management Heuristic algorithms Multi-service LEO satellite dynamic channel reservation strategy deep Q network

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Blind Identification Based on Expectation-Maximization Algorithm Coupled With Blocked Rhee-Glynn Smoothing Estimator

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IEEE COMMUNICATIONS LETTERS 2018年第9期22卷 1838-1841页

作者： Chen, Wenhao Ma, Lu liang, xuwen Chinese Acad Sci Shanghai Inst Microsyst & Informat Technol Shanghai 200050 Peoples R China Chinese Acad Sci Shanghai Engn Ctr Microsatellites Shanghai 201210 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Shanghai SpaceOK Aerosp Technol Co Ltd Shanghai 201802 Peoples R China

In this letter, we consider blind estimation of channel parameters over a frequency-selective channel. We use a blocked Rhee-Glynn smoothing estimator to derive E-step in the expectation-maximization (EM) algorithm. The proposed algorithm copes with the curse of dimensionality of a forward- backward algorithm;meanwhile, it is easy to parallelize, which is amenable to a modern computing hardware and speeds up the estimation of channel parameters. The experiment results show that the proposed algorithm is close to the Baum-Welch algorithm in terms of convergence of channel coefficients and outperforms the EM algorithm coupled with a joined two-filter smoothing algorithm in terms of convergence of channel coefficients and running time.

关键词： Maximum likelihood estimation multipath channels hidden Markov models Rhee-Clynn estimator expectation-maximization algorithm

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Symmetry Chirp Spread Spectrum Modulation Used in LEO Satellite Internet of Things

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IEEE COMMUNICATIONS LETTERS 2018年第11期22卷 2230-2233页

作者： Qian, Yubi Ma, Lu liang, xuwen Chinese Acad Sci Shanghai Inst Microsyst & Informat Technol Shanghai 100049 Peoples R China Chinese Acad Sci Shanghai Engn Ctr Microsatellites Shanghai 100049 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Shanghai SpaceOK Aerosp Technol Co Ltd Shanghai 201802 Peoples R China

With the development of Internet of Things (IoT), the world gradually moves toward the interconnection of all things. In terrestrial networks, narrowband-IoT and Long Rage (LoRa) are used widely in the IoT industry. For low-earthorbit (LEO) satellites, they have a lot of conspicuous advantages, such as broader coverage and lower construction cost. In this letter, we place emphasis on the application of LoRa-related technologies to LEO satellite communication systems, and the modulation is the prior research. Chirp spread spectrum (CSS) modulation is the most important technology in LoRa. Therefore, the research of CSS modulation used in the satellite IoT is imperative.

关键词： loT LEO Satellite NB-IoT LoRa CSS SCSS

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The Acquisition Method of Symmetry Chirp Signal Used in LEO Satellite Internet of Things

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IEEE COMMUNICATIONS LETTERS 2019年第9期23卷 1572-1575页

作者： Qian, Yubi Ma, Lu liang, xuwen Chinese Acad Sci Shanghai Inst Microsyst & Informat Technol Shanghai 200050 Peoples R China Chinese Acad Sci Shanghai Engn Ctr Microsatellites Shanghai 201210 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Shanghai SpaceOK Aerosp Technol Co Ltd Shanghai 201802 Peoples R China

Chirp signal has been used in some fields, like radar and sonar. In recent years, the symmetry chirp signal (SCS) is a kind of revised Long Range (LoRa) chirp signal and proposed to be used in low-earth-orbit (LEO) satellite Internet of Things (IoT) for low-data-rate transmission. However, in terms of the complexity and performance, the traditional acquisition methods to capture SCS (time delay and frequency offset acquisition) will have some limitations in LEO satellite IoT. Thus, this letter presents a new acquisition method to balance the complexity and performance for SCS.

关键词： Symmetry chirp signal LEO satellite IoT acquisition

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Heterogeneous temporal graph powered DRL algorithm for channel allocation in Maritime IoT Systems

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COMPUTER COMMUNICATIONS 2024年 213卷 260-270页

作者： Li, Zongwang Xie, Zhuochen He, Xiaohe liang, xuwen Chinese Acad Sci Innovat Acad Microsatellites 1 Xueyang Rd Shanghai 201304 Peoples R China Univ Chinese Acad Sci 1 Yanqihu East Rd Beijing 101408 Peoples R China

In actual maritime Internet of Things systems, the communication environment is characterized by its time-varying nature and the presence of highly heterogeneous network structures. Those attributes present considerable challenges in devising resource allocation strategies. Given the limited availability of frequency resources, designing a reasonable and flexible channel allocation strategy (CAS) is the primary task for meeting diverse and dynamic communication demands. In this paper, a heterogeneous temporal graph powered deep reinforcement learning algorithm is proposed to optimize the CAS to maximize the channel efficiency in a real-world maritime Internet of Things system. Specifically, we build relation-based heterogeneous edges to connect different types of terminal nodes and adopt a time encoding technology to capture the dynamic evolution of communication scenarios over time. The memory and public mailbox modules are constructed as the implementation entities of the information aggregation method based on the attention mechanism. In addition, we develop a corresponding heterogeneous temporal neural network to estimate the real-time resource requirements of target terminals, and subsequently learn the optimal CAS based on the deep reinforcement learning algorithm from the perspective of maximizing the cumulative channel efficiency. Simulation results prove that the proposed algorithm significantly outperforms the other state-of-the-art algorithms in terms of the channel efficiency and generalization ability.

关键词： Maritime IoT Heterogeneous temporal graph Deep reinforcement learning

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Intelligent Spectrum Sharing Strategy for Integrated Satellite-Maritime Heterogeneous Mobile Networks

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2024年第5期73卷 6780-6794页

作者： Wu, Ruiwen Li, Zongwang Xie, Zhuochen liang, xuwen Univ Chinese Acad Sci Beijing 100049 Peoples R China Shanghai Innovat Acad Microsatellites Shanghai 201304 Peoples R China Shanghai Engn Ctr Microsatellites Shanghai 201210 Peoples R China

Spectrum sharing is a pivotal technology for integrated satellite-maritime network to improve spectrum efficiency. However, the majority of existing spectrum sharing approaches relied on time-frequency multiplexing to circumvent or suppress interference, and often overlooked the problem of incomplete observability and interference present in heterogeneous systems. This limitation hindered overall system throughput improvements. In this article, an intelligent spectrum sharing strategy for integrated satellite-maritime heterogeneous mobile networks is firstly proposed. This strategy aims to operate co-frequency communication transmissions within the interference constraints, as derived from protocols and standards of International Telecommunication Union (ITU), to maximize the overall system throughput and spectral efficiency. Furthermore, considering the limitation that the satellite cannot fully observe channel statuses, we model the spectrum sharing process as a Partially Observable Markov Decision Process (POMDP). We employ an algorithm architecture that combines Dueling Deep Q-learning Network (DQN) and Double DQN to address this challenge, which enables satellites to efficiently evaluate the value of all channel allocation actions, thereby enhancing decision-making accuracy and algorithm convergence speed. Simulation results validate the superiority of our proposed strategy over compared methods in terms of throughput and stability.

关键词： Satellites Throughput Marine vehicles Interference Satellite broadcasting Optimization ITU Satellite-maritime heterogeneous mobile networks spectrum sharing interference constraints partially observable Markov decision process (POMDP) double dueling deep Q-learning network (DQN)

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On-Orbit Estimation and Calibration of GPS Antenna Geometry Offsets for Attitude Determination of LEO Satellites

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2018年第3期E101A卷 644-648页

作者： Hou, Huiling Hu, Weisheng Wu, Kang liang, xuwen Chinese Acad Sci Shanghai Inst Microsyst & Informat Technol Shanghai Peoples R China Chinese Acad Sci Shanghai Engn Ctr Microsatellites Shanghai Peoples R China Univ Chinese Acad Sci Beijing Peoples R China

In this letter, a novel on-orbit estimation and calibration method of GPS antenna geometry offsets for attitude determination of LEO satellites is proposed. Both baseline vectors in the NED coordinate system are achieved epoch-by-epoch firstly. Then multiple epochs' baseline vectors are united to compute all the offsets via an UKF for a certain long time. After on-orbit estimation and calibration, instantaneous and accurate attitude can be achieved. Numerical results show that the proposed method can obtain the offsets of each baseline in all directions with high accuracy estimation and small STDs, and effective attitudes can be achieved after antenna geometry calibration using the estimated offsets. The high accuracy give the proposed scheme a strong practical-oriented ability.

关键词： offset estimation calibration attitude determination LEO satellites

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