Space-Integrated-Ground Information Networks

On-Board Switching for Space-Integrated-Ground Information Network: Progress and Trends

Hao WU, Shuai WANG, Xiance DENG, Peilong LIU, Kai LIU, Jian YAN

2021, 2(2): 2-10. doi:10.11959/j.issn.2096-8930.2021014

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Considering the requirements of the space-integrated-ground information network, the technologies of on-board channelized switching and the technologies of on-board packet switching were surveyed.Among, the discussed channelized switching technologies include fl exible digital channelized switching and microwave photonic frequency conversion and switching, while the discussed packet switching technologies mainly include software-defi ned satellite network.Considering the future research directions of space networking and switching, the trends of on-board switching were discussed in terms of system capacity, reliability, effi ciency, and quality of service, which provided a reference for the long-term planning of the space-integrated-ground information network.

Review of Intelligent Routing Technology in Integrated Satellite-Ground Network

Suzhi CAO, Xue SUN, Houpeng WANG, Jiarong HAN, Siyan PAN, Lei YAN

2021, 2(2): 11-19. doi:10.11959/j.issn.2096-8930.2021015

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In view of the complex routing problems faced by the integrated satellite-ground network, the research progress of softwaredefi ned integrated satellite-ground network and intelligent routing was investigated.The training and deployment schemes of on-orbit routing mechanisms based on deep reinforcement learning were discussed, and a specifi c analysis was made in conjunction with the space intelligent computing platform.

Research on Coded Caching-Enabled Cooperative Transmission Mechanism in LEO Small Satellite Network

Jian LI, Kaiping XUE, Hancheng LU

2021, 2(2): 20-27. doi:10.11959/j.issn.2096-8930.2021016

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Along with the rapid development of low earth orbit (LEO) small satellite network, users can access content retrieval service through dense-deployed LEO satellite networks in the future.Due to the long propagation delay of satellite-to-terrestrial link, and also the constraint of limited communication resource and energy resource, it is diffi cult for satellites to provide effi cient content transmission service when facing the pressure of onboard overhead.A coded caching-based cooperative transmission mechanism was proposed in dense-deployed LEO small satellite network to achieve effi cient content distribution.By adopting fi ne-grained coded caching scheme, users could simultaneously receive cached packets from multiple LEO satellites to mitigated the cost of satellite backhaul link and improved the caching effi ciency.The simulation results showed that, after deploying onboard caching, the cost of content transmission could be reduced at least 39%.When coded caching-based transmission scheme was adopted, the cost of content transmission could be further reduced by 9%-42% with the increase of satellites providing cooperative transmission.

Research on Stateless Address Auto-Confi guration and Duplicate Address Detection in Space-Integrated-Ground Information Network

Yazheng CHEN, Hewu LI

2021, 2(2): 28-34. doi:10.11959/j.issn.2096-8930.2021017

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LEO (Low Earth Orbit) satellites with high mobility in space-integrated-ground information network cause ground user terminals change connected satellites continuously, so user terminals can't keep stable IPv6 addresses.SLAAC (Stateless Address Auto-Confi guration) in space-integrated-ground information network to provide stable IPv6 addresses was investigated, and an eff ective SLAAC and DAD (Duplicate Address Detection) mechanism was proposed.Aiming at the scenario where the ground equipment in the LEO satellite constellation constantly switches the LEO satellites, an IPv6 stateless address automatic confi guration and duplicate address detection mechanism was proposed.The scope of duplicate address detection was reduced by introducing ground position information and satellite orbit information, thereby eff ectively reduced signaling overhead for duplicate address detection.

Inter-Satellite Cooperative Computing Scheme Driven by Business Graph in LEO Satellite Network

Xiaobo GUO, Zhiyuan REN, Wenchi CHENG, Zhe JI

2021, 2(2): 35-44. doi:10.11959/j.issn.2096-8930.2021018

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Low earth orbit-satellite network (LEO-SN) has the advantages of wide coverage and short satellite-to-earth link, and has become a current hot research fi eld.A business graph-driven inter-satellite collaborative computing method in LEO-SN was proposed to solve the problem of high transmission delay when the task was o? oaded to the cloud computing center.This method shielded the dynamics of LEO-SN by relying on the weighted time expansion graph model, combined multiple satellite computing resources, and dispatches tasks in the form of a directed acyclic graph to the satellites in the transmission path, thereby realizing the ＆quot;computing while transmitting” of user services in the satellite cluster.The simulation results showed that when the data volume was 5 MB, the latency performance of on-orbit collaborative computing was improved by 58.9% compared to ground cloud computing.

Research on Optical/Electric Hybrid Switching Technique for Space-Integrated-Ground Information Network

Shanghong ZHAO, Cong PENG, Yongjun LI, Hai LI

2021, 2(2): 46-52. doi:10.11959/j.issn.2096-8930.2021019

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Space-integrated-ground information network will face the challenges of heterogeneous links, multi-granularity of information and limited resources in the process of networking.The problems can be solved by data switching design.The architecture of space-integrated-ground information network was described, and the present situation of multi-granularity service hybrid switching was analyzed.Based on this, the idea of hybrid optical/RF/packet switching was proposed, i.e., hybrid switching structure design, optical switching based on four-wave mixing eff ect, broadband confi gurable RF channelized switching, packet high-speed switching based on software radio idea, laser/RF heterogeneous link optical domain aggregation and grooming and enhanced general multi-protocol label switching design.

Effect of Optical Signal Beam Shift on the Performance of Satellite Chaos Laser Safety Communication System under Space-Integrated-Ground Information Network

Mi LI, Qiang CHEN, Cheng ZENG, Xue WANG, Yisi WANG, Xiangfei CHEN

2021, 2(2): 53-61. doi:10.11959/j.issn.2096-8930.2021020

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The eff ect of beam center shift on the performance of satellite chaos laser safety communication system in spaceintegrated-ground information network was studied, the bit error rate (BER) formulae with external and internal mismatch caused by beam center shift was conducted.Based on the BER formulae, the eff ect of beam center shift on external and internal mismatch and system performance was analyzed.The results show that beam wander will further increase external and internal mismatch based on pointing error then aff ect system performance.When pointing error is relatively small, optimizing beam wander will improve system performance more, and when pointing error is relatively large, optimizing internal mismatch will improve system performance more.The research results of this paper have important reference signifi cance for the actual engineering design of satellite chaos laser safety communication system, and lay the foundation for the promotion of terrestrial high-speed chaos laser safety technology to the fi eld of space-integrated-ground.

Research on Performance of Fiber-Based Multiple Apertures Receiver System with PPM Modulation

Kangning LI, Xu FENG, Jianwen GAO, Jing Ma

2021, 2(2): 62-68. doi:10.11959/j.issn.2096-8930.2021021

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The performance of fi ber-based FSO with multiple apertures receiver system was studied for pulse position modulation (PPM) .Expressions of PPM modulated signal-to-noise ratio (SNR) and bit-error rate (BER) for fi ber-based FSO multiple apertures receiver system were presented based on the probability density function of Gamma-Gamma intencity distribution and non–central chisquare fi ber coupling effi ciency distribution under atmospheric infl uence.Selection combining (SC), equal gain combining (EGC) and maximum ratio combining (MRC) were considered to be three signal combining methods for multiple apertures receiver system.The BER performance of 4PPM modulted SC, EGC and MRC fi ber-based multiple apertures receiver system and single aperture receiver system with the same total aperture area were comparative analyzed by Monte Carlo simulation.The BER performance of fi ber-based multiple apertures receiver systems in 4PPM and 8PPM modulation modes were directly compared for diff erent combining methods.

Research on Dynamic Equalization of Optical Power for Satellite-Ground Laser Communication

Yuefeng CAI, Haifeng LIU, Bo LIU, Wei LIN

2021, 2(2): 69-74. doi:10.11959/j.issn.2096-8930.2021022

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Aiming at the problem of light intensity scintillation caused by atmospheric turbulence at the receiver of satellite-ground laser communication will aff ect the communication quality, an optical power balance system based on gain competition was studied.The experiment verifi ed that the received power fl uctuation increased the communication bit error rate.The static output curve of the equalization system under gain competition was studied and the equalization performance of the dynamic time domain signal was tested.The experimental results showed that the system could compress the power fl uctuation range of the dynamic signal to 4 dB.

The Global Competitive Situation and Strategy of Space Frequency and Orbit Resources

Feng LAN, Zhaoqi PENG

2021, 2(2): 75-81. doi:10.11959/j.issn.2096-8930.2021023

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Combined with ITU Radio Rules and the actual in-orbit satellites situation, the satellite communication frequency resource allocation, the regulation and the use of orbital positions were analyzed, the planning and frequency-orbit resources of the international mainstream low-orbit internet constellations were expounded, and the satellite networks information on China's low-orbit constellation was listed.For the development of low-orbit internet constellations, it was proposed that China's low-orbit internet constellations should be based on China's national conditions, the new technologies and frequency bands should be used, to resolve the frequency resources bottleneck.

Discussion on the Development of Integrated and Intelligent Space TTC＆OC Network

Wei ZHANG, Tao WU, Hong MA, Yiwen JIAO, Yang CAI

2021, 2(2): 82-89. doi:10.11959/j.issn.2096-8930.2021024

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With the continuous development of aerospace applied research, the space system is rapidly developing towards space networking, integrated operation and intelligent service.Therefore, how to construct an integrated and intelligent space TTC＆OC network more and more becomes the key problem in developing our future national space TTC＆OC network.Aiming at this problem, the development status of the space TTC＆OC network at home and abroad were first analyzed, then the common problems and challenges of the space TTC＆OC network for the development of intelligent integration were summarized and analyzed.On this basis, an interpretation of the integrated and intelligent space TTC＆OC network was given.Preliminary design of the integrated and intelligent space TTC＆OC network architecture was also given.Furthermore, some key technical problems in constructing the future integrated and intelligent space TTC＆OC network were discussed.

Research on the Architecture of Phased Array Antenna of LEO Communication Satellites Based on Hybrid Beamforming

Rong HU, Xiumei LI, Juan DENG, Jun ZHOU, Shujing DONG, Ling LIU, Wenying MA

2021, 2(2): 90-97. doi:10.11959/j.issn.2096-8930.2021025

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Due to the characteristics of low earth orbit (LEO) communication satellite system like low propagation loss, small propagation delay and high pointing accuracy, a hybrid architecture-“analog beamforming stage and digital beamforming (DBF) stage” was proposed, and the principle and advantages of hybrid beamforming were analyzed.Through three dimensional integrating of multi-channel RF frontend chips, mixers, dedicated DBF ASIC chips, and tiles phased array anntena arrays, the proposed hybrid beamforming could be expanded or spliced.This hybrid architecture achieved the optimization of performance, cost, complexity and power consumption, and provided a reference for China to build space based internet of things system and reconfi gurable phased array antenna system in the future.

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