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arXiv 2024年

作者： Wu, Yanjun Xie, Zhong Xie, Zhuochen Ouyang, Chongjun liang, xuwen The Innovation Academy for Microsatellites Chinese Academy of Science Shanghai201304 China The Key Lab for Satellite Digitalization Technology Chinese Academy of Science Shanghai201210 China University of Chinese Academy of Sciences Beijing100049 China The Shanghai Engineering Center for Microsatellites Shanghai201210 China ShanghaiTech University Shanghai201210 China The National Space Science Center Chinese Academy of Sciences Beijing100190 China The School of Electrical and Electronic Engineering College of Engineering and Architecture University College Dublin DublinD04 V1W8 Ireland

The average multicast rate (AMR) is analyzed in a multicast channel utilizing analog beamforming with finite-alphabet inputs, considering statistical channel state information (CSI). New expressions for the AMR are derived for non-cooperative and cooperative multicasting scenarios. Asymptotic analyses are conducted in the high signal-to-noise ratio regime to derive the array gain and diversity order. It is proved that the analog beamformer influences the AMR through its array gain, leading to the proposal of efficient beamforming algorithms aimed at maximizing the array gain to enhance the AMR. © 2024, CC BY.

关键词： Multicasting

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DRL-Based Dynamic Destroy Approaches for Agile-Satellite Mission Planning

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REMOTE SENSING 2023年第18期15卷 4503页

作者： Huang, Wei Li, Zongwang He, Xiaohe Xiang, Junyan Du, Xu liang, xuwen ShanghaiTech Univ Sch Informat Sci & Technol Shanghai 201210 Peoples R China Chinese Acad Sci Innovat Acad Microsatellites Shanghai 201306 Peoples R China Univ Chinese Acad Sci Beijing 100039 Peoples R China Henan Acad Sci Inst Math HANS Zhengzhou 450046 Peoples R China

Agile-satellite mission planning is a crucial issue in the construction of satellite constellations. The large scale of remote sensing missions and the high complexity of constraints in agile-satellite mission planning pose challenges in the search for an optimal solution. To tackle the issue, a dynamic destroy deep-reinforcement learning (D3RL) model is designed to facilitate subsequent optimization operations via adaptive destruction to the existing solutions. Specifically, we first perform a clustering and embedding operation to reconstruct tasks into a clustering graph, thereby improving data utilization. Secondly, the D3RL model is established based on graph attention networks (GATs) to enhance the search efficiency for optimal solutions. Moreover, we present two applications of the D3RL model for intensive scenes: the deep-reinforcement learning (DRL) method and the D3RL-based large-neighborhood search method (DRL-LNS). Experimental simulation results illustrate that the D3RL-based approaches outperform the competition in terms of solutions' quality and computational efficiency, particularly in more challenging large-scale scenarios. DRL-LNS outperforms ALNS with an average scheduling rate improvement of approximately 11% in Area instances. In contrast, the DRL approach performs better in World scenarios, with an average scheduling rate that is around 8% higher than that of ALNS.

关键词： agile-satellite mission planning graph attention network deep-reinforcement learning large-neighborhood search dynamic destroy

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基于DQN的VDES异构星座兼容策略

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中国科学院大学学报（中英文） 2024年第4期41卷 550-557页

作者：王雪帆李宗旺梁旭文中国科学院微小卫星创新研究院上海201203 上海科技大学信息科学与技术学院上海201210 中国科学院大学北京100049

异构VDES(VHF data exchange system)星座采用相同的通信频率和时分多址通信机制,使得异构星座重复覆盖区域内存在大量由时隙冲突造成的同频干扰,严重影响通信质量。针对此问题,提出一种基于深度Q网络(DQN)的星座间兼容策略。基于VDES... 详细信息

异构VDES(VHF data exchange system)星座采用相同的通信频率和时分多址通信机制,使得异构星座重复覆盖区域内存在大量由时隙冲突造成的同频干扰,严重影响通信质量。针对此问题,提出一种基于深度Q网络(DQN)的星座间兼容策略。基于VDES通信流程,设置船站作为资源信息中转节点,赋予卫星对通信环境的感知能力。在此基础上,将异构星座场景下的资源分配问题建模为强化学习问题,提出一种基于DQN的时隙资源分配算法。通过重构历史资源信息和当前资源信息,规划最优时隙资源分配方案,并根据结果对算法迭代优化。仿真结果表明,所提出的策略可以有效提高通信性能。

关键词： VDES DQN 卫星通信干扰规避资源分配

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Satellite microvibration measurement based on distributed compressed sensing

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MEASUREMENT 2022年 203卷

作者： Li, Li Zhou, Miaomiao Zhu, Ye Dai, Ya liang, xuwen Chinese Acad Sci Innovat Acad Microsatellites Shanghai 201204 Peoples R China Shanghai Engn Ctr Microsatellites Shanghai 201204 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

To reduce the burden of multiple sensors on satellites with limited resources, distributed compressed sensing (DCS) is applied to microvibration measurement. An improved joint recovery algorithm using the recovered spectrum coefficients as the halting condition is proposed. This improvement can address the drawback that the previous algorithms need to anticipate signal sparsity or use residuals that do not reflect recovery accuracy in the frequency domain as the halting condition. In addition, acceleration is adopted in the improved algorithm. The DCS-based microvibration measurement was conducted on a satellite mechanical test model. The results reveal that the DCS measurement has a difference in the order of 1e-10 g2/Hz between the power spectrum density (PSD) of the raw data and the recovery data. With one-fifth sampling points of the raw signal, it can achieve a signal difference of less than 4% in PSD, which demonstrates the viability of satellite microvibration measure-ment based on DCS.

关键词： Microvibration measurement Distributed compressed sensing Joint recovery algorithm Power spectrum density

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Initial Assessment of LEO-Augmented GPS RTK in Signal-Degraded Environment

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2020年第7期E103A卷 942-946页

作者： Hu, Weisheng Hou, Huiling Xie, Zhuochen liang, xuwen He, Xiaohe Chinese Acad Sci Shanghai Inst Microsyst & Informat Technol Shanghai Peoples R China Univ Chinese Acad Sci Beijing Peoples R China Chinese Acad Sci Shanghai Engn Ctr Microsatellites Shanghai Peoples R China ShanghaiTech Univ Sch Informat Sci & Technol Shanghai Peoples R China

We simulate some scenarios that 2/3 LEO satellites enhance 3/4/5 GPS satellites, to assess LEO-augmented GPS RTK positioning in signal-degraded environment. The e ffects of LEO-augmented GPS RTK in terms of reliabilit... 详细信息

关键词： LEO-augmented RTK signal-degrade environment DIA

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基于混合波束赋形的毫米波大规模MIMO信道估计

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激光与光电子学进展 2022年第5期59卷 106-114页

作者：黄竞择梁旭文谢卓辰中国科学院微小卫星创新研究院上海201203 中国科学院大学北京100049

毫米波大规模多输入多输出系统依赖于准确的信道状态信息,然而毫米波的高频率使得用于信道估计的时间变短,以往单独利用其波束域的稀疏性或天线域的低秩特性的高复杂度估计算法不再可行。因此提出了一种新的估计算法,该算法结合了稀疏... 详细信息

毫米波大规模多输入多输出系统依赖于准确的信道状态信息,然而毫米波的高频率使得用于信道估计的时间变短,以往单独利用其波束域的稀疏性或天线域的低秩特性的高复杂度估计算法不再可行。因此提出了一种新的估计算法,该算法结合了稀疏和低秩两种特性,将信道估计看作矩阵完备问题,利用基于增广拉格朗日交替方向非精确牛顿法进行求解。经仿真验证,该算法具有更快的收敛速度和更高的准确度。

关键词：信道估计大规模MIMO 凸优化毫米波矩阵完备化

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Research on the Performance of Multi-GNSS Medium Length Baseline RTK with LEO-Augmented

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2020年第5期E103A卷 780-784页

作者： Hu, Weisheng liang, xuwen Hou, Huiling Xie, Zhuochen He, Xiaohe 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 ShanghaiTech Univ Sch Informat Sci & Technol Shanghai Peoples R China

In this letter, we simulate GNSS/LEO measurements and propose a process strategy for LEO-augmented GNSS medium length baseline RTK. Experiments show that, the performance of GNSS medium length baseline RTK can be significantly improved by introducing LEO satellites. The convergence speed of LEO-augmented GPS or BDS float solution maybe better than GPS/BDS combined under the conditions of similar satellite geometry. Besides, the RMS error of fixed solutions are improved to better than 4 cm from sub-decimeter level.

关键词： multi-GNSS LEO-augmented medium length baseline RTK

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VDE-SAT下行链路信道建模方法

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中国科学院大学学报（中英文） 2024年第2期41卷 249-256页

作者：丁港辉李宗旺谢卓辰梁旭文中国科学院微小卫星创新研究院中国科学院微小卫星重点实验室上海201203 中国科学院大学北京100049

海面的散射特性导致VDES海上通信信道模型复杂多变,在VDE-SAT下行链路中,低仰角通信导致海浪反射带来的多径效应更加严重。针对此问题,提出一种基于球坐标系的VDE-SAT下行链路信道建模方法,根据不同海情级分析海浪反射对于信号接收特性... 详细信息

海面的散射特性导致VDES海上通信信道模型复杂多变,在VDE-SAT下行链路中,低仰角通信导致海浪反射带来的多径效应更加严重。针对此问题,提出一种基于球坐标系的VDE-SAT下行链路信道建模方法,根据不同海情级分析海浪反射对于信号接收特性的影响。首先,将海面散射特性的统计结果参数化,结合地球曲率的影响,建立基于球坐标系的星船通信几何模型,基于此,得到海面有效漫反射区。其次,建立星船通信链路的信号多径传播模型,基于G1139协议,根据各个路径的信道参数分析接收信号的功率分布,以及不同海情级下信号的接收特性。仿真结果表明:在海况较好时,该多径信道以镜面反射为主;海况较差时,以漫反射为主。相比于卷积码,Turbo码的抗多径性能更优。

关键词： VDE-SAT 信道模型卫星通信多径效应

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Influence of coded mask rotation speed and central detector to imaging performance for time-encoded imager

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RADIATION PHYSICS AND CHEMISTRY 2023年第1期209卷

作者： Zhao, Dong Jia, Wenbao Hei, Daqian liang, xuwen Cheng, Wei Cai, Pingkun Zhang, Ronghua Shan, Qing Ling, Yongsheng Nanjing Univ Aeronaut & Astronaut Dept Nucl Sci & Technol Nanjing 211106 Peoples R China Lanzhou Univ Sch Nucl Sci & Technol Lanzhou 730000 Peoples R China Jiangsu Higher Educ Inst Collaborat Innovat Ctr Radiat Med Suzhou 215000 Peoples R China

Time-encoded imaging could be useful for searching potential radioactive sources for preventing illicit trans-portation and trafficking of nuclear materials. A 2-D, dual-particle, time-encoded imager was developed for gamma-ray and neutron source imaging. The influence of central detector and coded mask rotation speed to imaging performance, such as angular resolution, signal-to-noise ratio and detection time, was investigated by Am-Be neutron source imaging experiments. The EJ276 plastic scintillator (Size: phi 5.08 cm x 5.08 cm) and CLYC scintillator (Size: phi 2.54 cm x 2.54 cm) couple to photomultiplier tubes was set as the central detector, respectively. Under the experiment conditions (Am-Be neutron source;300 mCi;1.8 m), for the neutron and gamma-ray images with EJ276 detector, the best horizontal and vertical angular resolution was (3.7 degrees, 4.8 degrees) and (5.9 degrees, 6.6 degrees), minimum detection time was 100 s and 600 s, respectively;for the neutron and gamma-ray images with CLYC detector, the best horizontal, vertical angular resolution was (3.1 degrees, 3.1 degrees) and (3.5 degrees, 3.3 degrees), minimum detection time was 2200 s and 1600 s, respectively. For different central detector, the results showed that the smaller volume of detector, the better angular resolution;the lower detection efficiency, the longer detection time. For different rotation speed, too fast rotation speed can lead to failure to locate the source.

关键词： Time-encoded imager Dual-particle imaging Imaging performance

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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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