检索结果-南通市图书馆

A Recursive DRL-Based resource Allocation Method for Multibeam satellite Communication Systems

Chinese Journal of Electronics 2024年第5期33卷 1286-1295页

作者： Haowei MENG Ning XIN Hao QIN Di ZHAO State Key Laboratory of Integrated Services Networks Xidian University China Academy of Space Technology Institute of Telecommunication Satellite

Optimization-based radio resource management(RRM) has shown significant performance gains on high-throughput satellites(HTSs). However, as the number of allocable on-board resources increases, traditional RRM is difficult to apply in real satellite systems due to its intense computational complexity. Deep reinforcement learning(DRL) is a promising solution for the resource allocation problem due to its model-free advantages. Nevertheless, the action space faced by DRL increases exponentially with the increase of communication scale, which leads to an excessive exploration cost of the algorithm. In this paper, we propose a recursive frequency resource allocation algorithm based on long-short term memory(LSTM) and proximal policy optimization(PPO), called PPO-RA-LOOP,where RA means resource allocation and LOOP means the algorithm outputs actions in a recursive manner. Specifically, the PPO algorithm uses LSTM network to recursively generate sub-actions about frequency resource allocation for each beam, which significantly cuts down the action space. In addition, the LSTM-based recursive architecture allows PPO to better allocate the next frequency resource by using the generated sub-actions information as a prior knowledge, which reduces the complexity of the neural network. The simulation results show that PPO-RA-LOOP achieved higher spectral efficiency and system satisfaction compared with other frequency allocation algorithms.

关键词： High-throughput satellites Proximal policy optimization Deep reinforcement learning Long-short term memory High-throughput satellites Proximal policy optimization Deep reinforcement learning Long-short term memory OPTIMIZATION POWER

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Characterizing extreme drought and wetness in Guangdong,China using global navigation satellite system and precipitation data

引用

satellite Navigation 2024年第1期5卷 258-274页

作者： Hai Zhu Kejie Chen Haishan Chai Yuanbin Ye Wenjian Liu Department of Earth and Space Sciences Southern University of Science and TechnologyShenzhen518055China Lands and resource Department of Guangdong Province Surveying and Mapping InstituteGuangzhou510500China

As global temperature rises,the frequency of extreme climate events,e.g.,severe droughts and floods,has increased significantly and caused severe damage over the past *** this regard,precipitation efficiency,a crucial meteorological parameter,could provide valuable insights for a better understanding of the patterns and characteristics of these extreme *** this study,taking Guangdong province as an exemplary region,we first obtained long-term and high-resolution historical records of precipitation efficiency by integrating the observations from a dense network of Global Navigation satellite System(GNSS)stations with precipitation data,and then characterized the extreme drought and wetness through climate *** found a distinct seasonal trend in precipitation efficiency in Guangdong,with annual fluctuations ranging from 10 to 25%.Notably,precipitation efficiency is higher in proximity to the Pearl River Delta Plain and gradually decreases towards the east and *** occurrence of anomalous peaks and valleys in precipitation efficiency generally corresponds to dry and wet conditions,respectively.A total of 9 extreme wet events and 6 dry events occurred from January 2007 to May 2022,with durations from 3 to 6 *** results also demonstrated that both wet and dry frequencies exhibit an increasing trend with the expansion of the time scale,and the frequency of extreme events near the Pearl River Delta Plain surpasses that of other ***,the propagation time from meteorological anomalies to agricultural and hydrological anomalies is about 3 *** periodic characteristics of meteorological anomalies are identified as the primary driver for other anomalous periodic *** work unveils the long-term dynamic behavior of precipitation efficiency,as well as the characteristics of extreme drought and wetness events in the regions characterized by intricate land–atmosphere interactions.

关键词： GNSS Precipitation efficiency Extreme drought and wetness

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Belief Propagation List Decoding for Polar Codes:Performance Analysis and Software Implementation on GPU

引用

中国通信:英文版 2023年第9期20卷 115-126页

作者： Zhanxian Liu Wei Li Lei Sun Wei Li Jianquan Wang Haijun Zhang School of Computer&Communication Engineering University of Science and Technology BeijingBeijing 100083China satellite frequency and orbit resource agency State Radio Monitoring CenterBeijing 100041China School of Automation and Electrical Engineering University of Science and Technology BeijingBeijing 100083China Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services Institute of Artificial IntelligenceUniversity of Science and Technology BeijingBeijing 100083China

Belief propagation(BP)decoding outputs soft information and can be naturally used in iterative *** list(BPL)decoding provides comparable error-correction performance to the successive cancellation list(SCL)*** this paper,we firstly introduce an enhanced code construction scheme for BPL decoding to improve its errorcorrection ***,a GPU-based BPL decoder with adoption of the new code construction is ***,the proposed BPL decoder is tested on NVIDIA RTX3070 and *** results show that the presented BPL decoder with early termination criterion achieves above 1 Gbps throughput on RTX3070 for the code(1024,512)with 32 lists under good channel conditions.

关键词： polar code belief propagation SIMT list decoding GPU

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Approach to inter-satellite time synchronization for micro-satellite cluster

引用

Journal of Systems Engineering and Electronics 2018年第4期29卷 805-815页

作者： XU Jiuling ZHANG Chaojie WANG Chunhui JIN Xiaojun Micro-satellite Research Center Zhejiang University

Micro-satellite cluster enables a whole new class of missions for communications, remote sensing, and scientific research for both civilian and military purposes. Synchronizing the time of the satellites in a cluster is important for both cluster sensing capabilities and its autonomous operating. However, the existing time synchronization methods are not suitable for microsatellite cluster, because it requires too many human interventions and occupies too much ground control resource. Although, data post-process may realize the equivalent time synchronization, it requires processing time and powerful computing ability on the ground, which cannot be implemented by cluster itself. In order to autonomously establish and maintain the time benchmark in a cluster, we propose a compact time difference compensation system（TDCS）, which is a kind of time control loop that dynamically adjusts the satellite reference frequency according to the time difference. Consequently, the time synchronization in the cluster can be autonomously achieved on-orbit by synchronizing the clock of other satellites to a chosen one＇s. The experimental result shows that the standard deviation of time synchronization is about 102 ps when the carrier to noise ratio（CNR） is 95 d BHz, and the standard deviation of corresponding frequency difference is approximately0.36 Hz.

关键词： time difference measurement time synchronization dynamical reference frequency adjustment micro-satellite cluster

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Global precipitation from FY-3 polar orbit satellites

引用

Science Bulletin 2024年第17期69卷 2688-2692页

作者： Runze Zhao Kaicun Wang Xiangde Xu State Key Laboratory of Earth Surface Processes and resource Ecology Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China Institute of Carbon Neutrality Sino-French Institute for Earth System ScienceCollege of Urban and Environmental SciencesPeking UniversityBeijing 100871China

Precipitation provides water resources but can also cause disasters. The amount, intensity, and frequency of precipitation have significant impacts on ecosystems, people’s health, and socioeconomic systems [1]. However, due to its spatiotemporal discontinuity, accurately estimating precipitation remains a great challenge[2]. To estimate global precipitation at the required spatial and temporal resolutions, active microwave and passive microwave(PMW) observations from low-Earth-orbit satellites and infrared observations from geostationary satellites must be *** Integrated Multi-satellite Retrievals for Global Precipitation Measurement (IMERG) product is one of the best such products and provides global precipitation data at 0.1°and half-hour resolutions [3].

关键词： satellites microwave Global

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Airborne geometry correction method for marine multispectrum data without attitude information

引用

Acta Oceanologica Sinica 2012年第1期31卷 59-65页

作者： WANG Difeng PAN Delu GONG Fang WANG Tianyu State Key Laboratory of satellite Ocean Environment Dynamics Second Institute of OceanographyState Oceanic AdministrationHangzhou 310012China

Marine airborne multispectrum scanner （MAMS） onboard the China marine surveillance plane can be used to survey marine environment, resources and disaster and provide the technical support for high-frequency, high-efficiency and high-resolution remote sensing monitoring for the coastal management. MAMS did not have the IMU/POS equipment, so it brought severe challenge for the geometry correction. One airborne geometry correction method is introduced for marine multi- spectrum data without the attitude information. First, it is the coarse geometry correction, which simulates the roll angle and pitch angle of plane according to the ideal flying model; the second step is the precise geometry correction by using the SPOT orthogonal projected data as the reference of registration, based on maximization of alignment metric method. With the validation, relative error of coarse correction is 81.42 m compared with SPOT data, and 11.3 m for precise correction. This method provides the high precision localization information for the oceanic remote sensing and application, and establishes the foundation for monitoring the marine resource and environment.

关键词： multispectrum geometric correction airborne remote sensing

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Design and performance evaluation of a novel ranging signal based on an LEO satellite communication constellation

引用

Geo-Spatial Information Science 2023年第1期26卷 107-124页

作者： Jingfang Su Jia Su Qingwu Yi Cailun Wu Weimin Hou School of Information Science and Engineering Hebei University of Science and TechnologyShijiazhuangChina The State Key Laboratory of satellite Navigation System and Equipment Technology ShijiazhuangChina

Driven by improvements in satellite internet and Low Earth orbit(LEO)navigation augmenta-tion,the integration of communication and navigation has become increasingly common,and further improving navigation capabilities based on communication constellations has become a significant *** the context of the existing Orthogonal frequency Division Multiplexing(OFDM)communication systems,this paper proposes a new ranging signal design method based on an LEO satellite communication *** LEO satellite Communication Constellation Block-type Pilot(LSCC-BPR)signal is superimposed on the com-munication signal in a block-type form and occupies some of the subcarriers of the OFDM signal for transmission,thus ensuring the continuity of the ranging pilot signal in the time and frequency *** estimation in the time and frequency domains is performed to obtain the relevant distance value,and the ranging accuracy and communication resource utilization rate are *** characterize the ranging performance,the Root Mean Square Error(RMSE)is selected as an evaluation *** show that when the number of pilots is 2048 and the Signal-to-Noise Ratio(SNR)is 0 dB,the ranging accuracy can reach 0.8 m,and the pilot occupies only 50%of the communication subcarriers,thus improving the utilization of communication resources and meeting the public demand for communication and location services.

关键词： Integration of communication and navigation LEO communication constellation ranging LEO navigation augmentation satellite internet

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

System Design for the Event Horizon Imaging Experiment Using the PECMEO Concept

引用

空间科学学报 2019年第2期39卷 250-266页

作者： KUDRIASHOV Volodymyr MARTIN-NEIRA Manuel BARAT Itziar MARTIN IGLESIAS Pertonilo DAGANZO-EUSEBIO Elena ALAGHA Nader VALENTA Vaclav European Space Research and Technology Centre the European Space Agency

The concept for space interferometry from Polar or Equatorial Circular Medium Earth orbits(the PECMEO concept) is a promising way to acquire the image of the"shadow"of the event horizon of Sagittarius A*with an angular resolution of circa 5 microarcseconds. The concept is intended to decrease the size of the main reflector of the instrument to about 3 m using a precise orbit reconstruction based on Global Navigation satellite System (GNSS) navigation, inter-satellite range and range-rate measurements, and data from the Attitude and orbit Determination System (AODS). The paper provides the current progress on the definition of the subsystems required for the concept on the basis of simulations, radio regulations, and available technology. The paper proposes the requirement for the localization of the phase centre of the main reflector. The paper provides information about the visibility of GNSS satellites and the needed accuracies of the AODS. The paper proposes the frequency plan for the instrument and its Inter-satellite Links (ISLs).The concepts for measurement of range and range-rate using ISLs (as well as for the data exchange at these ISLs) are presented. The block diagram of the interferometer is described and its sensitivity is estimated. The link budget for both ISLs is given as well as their critical components. The calculated measurement quality factors are given. The paper shows the expected performance of the sub-systems of the interferometer. The requirements for the localization of the main reflectors and the information about the availability of the GNSS satellites are based on the simulations results. The frequency plan is obtained according to the PECMEO concept and taking into account the radio regulations. The existing technology defines the accuracies of the AODS, both the link budgets and the fundamental measurement accuracies for ISLs, and the sensitivity of the instrument. The paper provides input information for the development of the orbit r

关键词： Instrumentation Telescope High angular resolution Interferometer Space VLBI

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

In flight MTF monitoring and compensation for CCD camera on CBERS-02

引用

Science China(Technological Sciences) 2005年第S2期48卷 29-43页

作者： GU Xingfa1,2,3, LI Xiaoying1,2,4, MIN Xiangjun5, YU Tao1,2, SUN Jijuan5, ZENG Yong1,2,4, XU Hua1,2 & GUO Ding2,6 1. State Key Laboratory of Remote Sensing Science, Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University, Beijing 100101, China 2. The Center for National Spaceborne Demonstration, Beijing 100101, China 3. Institut National de la Recherche Agronomique, Climat Sol Environnement, 84914 Avignon, France 4. Graduate University of Chinese Academy of Sciences, Beijing 100039, China 5. China Center for resource satellite Data and Application, Beijing 100830, China 6. University of Electronic Science and Technology of China, Chengdu 610054, China State Key Laboratory of Remote Sensing Science Beijing Normal University Chinese Academy of Sciences Beijing 100101 China Center for National Spaceborne Demonstration Beijing 100101 China Institut National de la Recherche Agronomique Climat Sol Environnement 84914 Avignon France Graduate University Chinese Academy of Sciences Beijing 100039 China China Center for resource satellite Data and Application Beijing 100830 China University of Electronic Science and Technology of China Chengdu 610054 China

In this article, the approach of simulating ideal tarp scene was proposed to determine the MTF for CCD camera on CBERS-02. The MTF acquired from this technique was compared to those from some common methods. MTFs achieved from different approaches were employed to compensate the CCD images based on three restoration algorithms: the iterative method, the Wiener filter and the modified inverse filter (MIF). The two-dimensional MTF was established with the value at frequency 0.5 for 45° directional MTF as the value at its four corners. This article addressed the variations of the restored CCD images with different techniques of constructing two-dimensional MTF, restoring algorithms and determining the in-flight MTFs. Results showed images restored with the MTF determined from the technique of simulating ideal tarp scene represent the real scene best. And the restoration technique based on the MIF would produce better restored images than the other two techniques. This research also demonstrated that the two-dimensional MTF used for restoration should be interpolated under the control of the MTF for 45° axis, rather than by multiplying the cross-orbit MTF with along-orbit MTF.

关键词： CBERS-02 CCD MTF the technique of simulating ideal tarp scene.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Stability validation on the VLF waveform data of the China-Seismo-Electromagnetic satellite

引用

Science China(Technological Sciences) 2022年第12期65卷 3069-3078页

作者： YANG DeHe ZHIMA ZeRen WANG Qiao HUANG JianPing WANG XiuYing ZHANG ZhenXia ZHAO ShuFan GUO Feng CHENG WanLi LU HengXin SHEN XuHui National Institute of Natural Hazards Ministry of Emergency Management of ChinaBeijing 100085China Henan Earthquake agency Zhengzhou 450016China

The China-Seismo-Electromagnetic satellite(CSES),which was launched in February 2018,carries the search coil magnetometer(SCM)and the electric field detector(EFD)to realize the high-resolution electromagnetic field and wave detection in the upper *** to the complexity and variability of the ionospheric environment,the stability of such a high sampling rate and high-precision electromagnetic field detection systems is always an essential link in data processing and the scientific application of *** work evaluates the stability of the very-low-frequency(VLF)band detection by validating the systemic sampling-time differences between SCM and EFD in the VLF burst-mode *** optimal waveform data preprocessing method is put forward according to the noise levels of the VLF burst-mode observation and the inherent design characteristics of *** VLF waveform data of EFD is rebuilt by filling the data gaps among the sampling sub-periods,making it with a similar sample length to *** by precisely intercepting the maximum and minimum values of the burst-mode waveforms,the variation of the sampling-time difference between EFD and SCM is statistically *** show that during the three years'operation,the sampling-time difference between EFD and SCM predominately keeps below 0.5 s,indicating good stability of EFD and SCM on *** we developed an automatic synchronization tool based on the similarity function and STA/LTA(short time average over long time average)characteristic *** tool can effectively realize the precise synchronization between SCM and EFD in the VLF burst-mode *** work is helpful to upgrade the data quality of CSES and provides technical support for electromagnetic wave propagation studies.

关键词： stability CSES EFD SCM sampling-time difference quasiperiodic waves

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：