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20 December 2023, Volume 4 Issue 4

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Studies

Dynamic Beam Hopping Algorithm for LEO Satellite Systems Based on User Grouping

Qing SHU, Weibiao LI, Zuolin JIN, Zhong ZHENG, Yongbo ZHANG, Zesong FEI

2023, 4(4):  1-10.  doi:10.11959/j.issn.2096-8930.2023037

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In a satellite communication system deployed with massive MIMO, when the number of users far exceeds the number of beams of the satellite, it is still difficult to satisfy the delay requirements of the satellite communication system even if the number of RF chains is increased, i.e., the number of concurrently serving users is increased.To address the above problems, it proposed a dynamic beam hopping (BH) scheme based on user grouping for communication service coverage.The proposed method utilized the sparsity of the angular domain channel distribution to adaptively divide user groups accorded to the beam direction where the user energy is maximum.The number of co-channel user groups was constrained by power and interference constraints, limiting the reduction of communication traffic delay, as power limitations on the satellite make the number of RF chains limited and increased the number of simultaneously served user groups increased the interference between user groups.So the BH scheme with beam cluster grouping was further proposed, when the beam clusters reduced the user delay by increased the number of users served at the same moment.Since the above problem was non-convex, it adopt a data-driven determinantal point process (DPP) learning method to simplify the beam scheduling in BH scheme.Simulation results showed that the dynamic BH algorithm based on user grouping could effectively reduce the average user delay by more than 52% compared with the single-beam scheme, also verifies the versatility of the DPP learning.

Architecture and Features of Mobile Communication Satellite System for Mobile Phone

Dong CHEN, Qian ZHANG, Zhaotao QIN, Jincheng TONG

2023, 4(4):  11-18.  doi:10.11959/j.issn.2096-8930.2023038

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The development and construction of mobile communication satellite systems for individual users worldwide have been ongoing for over thirty years, and the technological level and industrial scale of satellite mobile communication are constantly maturing.Under the trend of deep integration of satellite communication and ground communication systems, the new generation of mobile communication satellites that support mobile phone connection is a new direction for the development of satellite-ground convergence.This paper expounded the development prospect and driving force of satellite system supporting mobile phone connection, proposed the mobile communication satellite network architecture based on GSO satellite and LEO satellite constellation, and analyzed the network characteristics and satellite technical challenges introduced in the above architecture from the perspective of satellite.Finally, the network communication system and related key issues were discussed.

Exploration and Analysis of Resource Scheduling and Management Mode in Future Space TT＆C Network

Hong ZHANG, Jia XUE, Bo REN, Xiaojun DU, Meng XUE

2023, 4(4):  19-26.  doi:10.11959/j.issn.2096-8930.2023039

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The running mode and existing issues of current resource scheduling system operation model of TT＆amp;C network were discussed firstly.Then the development trends of future resource scheduling and management models were summarized, included integration of data transmission, automation of system operation, intelligence of algorithm allocation, coexistence of random access and pre-allocation.In the end, accorded to the management demands of integration, automation and intelligentization, the operating framework of the future resource scheduling model was put forward.After that, the key technologies which need to be broken through of the framework were researched deeply.And the further construction object of resource scheduling research was proposed in order to provided a reference for subsequent engineering applications.

Research on Random Access of Satellite Internet of Things Based on Load Prediction

Xiwen MAO, Haitao WANG, Gengxin ZHANG

2023, 4(4):  27-37.  doi:10.11959/j.issn.2096-8930.2023040

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In the process of the vigorous development of satellite internet of things, random access protocol is regarded as the most suitable communication protocol due to its characteristics of low signaling overhead, high transmission efficiency, high flexibility and easy implementation.However, due to drastic load changes, conventional random access mode only has advantages in the specific load range.Dynamic allocation of random access resources requires the accurate number of time slot access applications.In view of the above problems, a random access adaptive scheme was proposed, which could adaptively selected the appropriate random access mode according to the future load size, so as to improved the system throughput.The load size could be obtained through the proposed load estimation and prediction scheme.When narrowband interference exists in the transmission environment, the spread-spectrum communication means was introduced to made the adaptive scheme of random access run successfully.Moreover, the proposed adaptive scheme also improved the system throughput.

Power Allocation Technology of Long Time Multi-Star Hopping Beam for LEO Satellite

Ziyi LIU, Xiaoning ZHANG, Zesong FEI

2023, 4(4):  38-48.  doi:10.11959/j.issn.2096-8930.2023041

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LEO satellites have superior development prospects due to their low cost, low latency and small path loss, and are widely used in IoT, B5G and other fields.For the LEO satellite and its coverage area will be in a moving state, a convex optimization-based long-time multi-star beam hopping power allocation algorithm was proposed to maximize the system capacity.Focused on the multi-star hopping beam scenario over a period of time, a system model was developed based on the long-time co-orbital multi-star hopping beam scenario and the long-time heterodyne multi-star hopping beam scenario respectively.The resource allocation algorithm was designed for the two long-time multi-star hopping beams with the weighted objective function as the optimization objective, considered the influence factors of inter-star interference, load balancing and inter-star resource allocation priority, a long-time skipping beam resource allocation algorithm based on convex optimization was proposed.The simulation results showed that the proposed scheme could improve the resource utilization of the system compared with the conventional schemes.

Intelligent Load Balancing Algorithm of Mega Constellation

Shuxin LUO, Chao ZHANG, Yong XIAO, Jianping LIU

2023, 4(4):  49-60.  doi:10.11959/j.issn.2096-8930.2023042

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To overcome the local traffic congestion caused by the huge number of satellites in mega-constellation, a load balancing algorithm based on multi-agent deep reinforcement learning was proposed.Firstly, the satellites in the mega constellation were divided into clusters to perform the distributed management of the mega constellation, which could reduce the overhead of whole network.Then, based on the coordinated multi-agent deep reinforcement learning model, routing planning, which could be individually operated by satellites in the mega constellation, was designed to achieve the intra-cluster coordination.Additionally, a cluster state compression mechanism with autoencoder was proposed to compress the state space and improve the efficiency of multi-agent deep reinforcement learning.Finally, simulation results showed that compared with the traditional single-task routing algorithm, the proposed algorithm could increase the transmission success rate by more than 40% and the proposed algorithm could efficiently avoid local traffic congestion.

Integrity Monitoring Technology of Mixed Constellation of High, Medium and Low Orbit Navigation Based on Genetic Algorithm Star Selection

Zhengcheng WU, Shaojie NI, Wenxiang LIU, Wei XIAO, Zongnan LI

2023, 4(4):  61-70.  doi:10.11959/j.issn.2096-8930.2023043

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Low-orbit satellites are widely used in communication, navigation, remote sensing and other fields, which is of great significance to meet the needs of communication and improve the accuracy of navigation and positioning.Integrity technology is an important guarantee for the safe and reliable operation of satellite navigation system.With the mature development of low orbit technology and the gradual application of a large number of low orbit satellites, it is urgent to develop the system integrity monitoring technology under the condition of mixed constellation of high and low orbits.This paper proposed a hybrid constellation integrity monitoring technology for high, middle and low orbit navigation based on genetic algorithm for star selection.On the basis of the traditional optimal geometric accuracy factor selection method, genetic algorithm was introduced to construct a fitness factor based on the linear weighted feature slope of the satellite geometric observation matrix, so as to achieve rapid convergence of user protection level to protection limit.This method further improved the integrity of the receiver by optimizing the way of star selection.Under the accuracy requirement of CAT I, for the ＆quot;BeiDou+StarNet-1＆quot; constellation, the global availability level of the proposed algorithm was 5.60%, and the enhancement effect was the best for the mid-latitude and low-latitude of the Eastern Hemisphere, which were increased by 7.01% and 6.42%, respectively.

Lightweight Design Strategy and Performance Optimization of Spaceborne Core Network

Xi CHEN, Yiqun Zhao, Minghan ZHANG, Shan LU, Shihao WANG, Chengchen ZHANG, Xiaofan XU, Ping DU

2023, 4(4):  71-78.  doi:10.11959/j.issn.2096-8930.2023044

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With the growth of global communication demand, the spaceborne core network can not only reduce frequent signaling interactions between satellites and the ground, but also break through the constraints of geographical regions, providing strong support for the integrated network architecture of heaven and earth and global communication operations.However, due to the resource limitations of satellites and the dynamic and time-varying topology of satellite internet on a large scale, the deployment of traditional core network elements in spaceborne environments has encountered significant challenges.This article is dedicated to studying the challenges of lightweight, flexible deployment, and low latency in onboard core networks, aiming to explore new design strategies for onboard lightweight core networks and provide a solid theoretical foundation for global communication operations.Multiple lightweight strategies, including minimum network element set deployment, single network element function tailoring, interface protocol lightweight, network element fusion and reconstruction, platform architecture lightweight, and transmission protocol reconstruction were firstly studied.Then, detailed simulation experiments were conducted on the selected strategies, and the experimental results confirmed that the lightweight processing of the spaceborne core network has superior performance in resource allocation and signaling process.

Applications

Scalable Low Power Accelerator for Sparse Recurrent Neural Network

Panshi JIN, Junjie LI, Jingyi WANG, Pengchong LI, Lei XING, Xiaodong LI

2023, 4(4):  79-85.  doi:10.11959/j.issn.2096-8930.2023045

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The use of edge computing devices in bank outlets for passenger flow analysis, security protection, risk prevention and control is increasingly widespread, among which the performance and power consumption of AI reasoning chips have become a very important factor in the selection of edge computing devices.Aiming at the problems of recurrent neural network, such as high power consumption, weak reasoning performance and low energy efficiency, which were caused by data dependence and low data reusability, this paper realized a sparse RNN low-power accelerator with scalable voltage by using FPGA, and verifies it on the edge design and calculation equipment.Firstly, the sparse -RNN was analyzed and the processing array was designed by network compression.Secondly, due to the unbalanced workload of sparse RNN, it introduced voltage scaling method to maintain low power consumption and high throughput.Experiments show that this method could significantly improve the RNN reasoning speed of the system and reduce the processing power consumption of the chip.

Internationalized Satellite Internet Business Operation Platform

Wenlong ZENG, Shuang ZHAO, Shaopeng CHEN, Tao JIN, Chang JIANG

2023, 4(4):  86-93.  doi:10.11959/j.issn.2096-8930.2023046

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Through quantitative analysis of the business market prospects for satellite internet and analyses of international business operation service models, the study explained the necessity of conducting satellite internet operation service.Therefore, further research on how to establish an internationalized satellite internet business operation platform becomes particularly important.On this basis, it primarily discussed a mid-tiered architecture with flexibly and scalability for the operation platform, proposes a tiered collaborative deployment architecture and mechanism for international operations, conducts research on multi-tenant management methods for global market operations, and suggests a roadmap for the integration of satellite internet operators with ground operators, which is providing valuable guidance for the future development of satellite internet operation platform.