电子学报 ›› 2022, Vol. 50 ›› Issue (1): 1-17.DOI: 10.12263/DZXB.20210690

• 无线光通信及其组网技术 •    下一篇

空天地一体化无线光通信网络关键技术及其发展趋势

赵雄文1,2, 张钰1,2, 秦鹏1,2, 王晓晴1,2, 耿绥燕1,2, 宋俊元1,2, 刘瑶1,2, 李思峰1,2   

  1. 1.华北电力大学新能源电力系统国家重点实验室,北京 102206
    2.华北电力大学河北省电力物联网技术重点实验室,河北 保定 071003
  • 收稿日期:2021-05-29 修回日期:2021-08-05 出版日期:2022-01-25 发布日期:2022-01-25
  • 作者简介:赵雄文 男,1964年生,陕西清涧人.中国电子学会会士,华北电力大学教授,博士生导师,通信工程国家一流专业负责人,信息与通信工程学科责任教授.主要研究方向为无线通信与电力系统通信等.
    张 钰(通信作者) 女,1995年生,安徽六安人.华北电力大学电气与电子工程学院博士研究生.主要研究方向为5G,B5G无线通信技术.
  • 基金资助:
    国家自然科学基金重点项目(61931001);国家自然科学基金(61771194);新能源电力系统国家重点实验室开放课题(LAPS21018);中央高校科研基金(2021MS002)

Key Technologies and Development Trends for a Space-Air-Ground Integrated Wireless Optical Communication Network

ZHAO Xiong-wen1,2, ZHANG Yu1,2, QIN Peng1,2, WANG Xiao-qing1,2, GENG Sui-yan1,2, SONG Jun-yuan1,2, LIU Yao1,2, LI Si-feng1,2   

  1. 1.State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources,North China Electric Power University,Beijing 102206,China
    2.Hebei Key Laboratory of Power Internet of Things Technology,North China Electric Power University,Baoding,Hebei 071003,China
  • Received:2021-05-29 Revised:2021-08-05 Online:2022-01-25 Published:2022-01-25

摘要:

构建空天地一体化信息网络是第六代通信系统(the Sixth Generation,6G)的重要目标,无线光通信相较于射频(Radio Frequency,RF)通信技术具有容量大、速率高、抗干扰能力强等优势,已成为建立全球无缝覆盖空间网络的重要技术.本文综述了基于自由空间光通信(Free Space Optical Communication,FSOC)的空天地一体化网络国内外建设及相关标准化现状,相较于现有综述文献,涵盖了更多最新研究工作,并针对物理层和上层指出一体化FSOC网络设计需要关注的重要因素,对大气信道建模、“捕获、瞄准和跟踪”(Acquisition Pointing and Tracking,APT)、拓扑控制、路由、资源分配、可靠传输协议、微波协作传输几种重要通信技术进行总结和分析,并指出其未来发展趋势和面临的挑战.

长摘要
构建空天地一体化信息网络是6G的重要目标,无线光通信相较于射频通信技术具有容量大、速率高、抗干扰能力强等优势,成为建立全球无缝覆盖空间网络的重要技术. 目前,大量研究工作集中于从物理层提升自由空间光通信(Free Space Optical Communication,FSOC)的性能,FSOC网络上层关键技术的研究多数着眼于地面光网络或卫星光网络,尚未形成针对空天地一体化FSOC网络的解决方案.本文综述了空天地一体化FSOC网络的建设和标准化现状、设计因素及关键技术,着重从物理层之上审视一体化 FSOC 网络建设面临的主要挑战.本文主要观点总结如下:国内外针对卫星、平流层及地面网络各层内链路及层间链路进行了大量激光通信实验,并提出了铱星系统、OneWeb、鸿雁等多项空间网络建设项目,为一体化 FSOC 网络建设奠定了坚实的基础. 然而 FSOC标准化文件仅限于物理层及数据链路层,缺乏上层的标准化工作; 为充分了解光信号在大气中的传输特性,需要提高大气信道建模精度,为网络算法设计和协议优化提供准确的底层模型;捕获、瞄准和跟踪技术是确保 FSOC 链路稳定性的重要前提,需进一步减小体积和硬件复杂度,提高在终端高速移动时的性能;拓扑控制、路由和资源分配等技术还需投入大量研究,以匹配一体化 FSOC 网络特性,优化网络性能;传统传输控制协议(Transmission Control Protocol,TCP)不能适应高速、长时延、高丢包率的网络,必须针对一体化 FSOC 网络研发专门的传输协议或改进现有TCP协议;FSOC传输性能受到链路特性的制约,应考虑 FSOC/X的混合传输方式以适应多样化的应用场景.

关键词: 空天地一体化自由空间光通信网络, 信道建模, APT, 拓扑控制, 路由, 资源分配, 可靠传输协议, 微波协作传输

Abstract:

Space-air-ground integrated information network has become a key target of building the six generation(6G) communication system. Compared to radio frequency(RF) technology, wireless optical communication has the advantages of large capacity, high data rate and strong anti-interference ability, which makes it becomes an indispensable technology to establish a global seamless coverage network. In this paper, the research progress and standardization for free space optical communication(FSOC) based space-air-ground integrated information networks were presented, which cover more recent research work compared with the existing literature reviews. The critical factors of physical and upper layer in designing integrated FSOC networks were also discussed. Several important communication technologies such as atmospheric channel modeling, APT(Acquisition, Pointing and Tracking), topology control, routing, resource allocation, reliable transmission protocol, and microwave cooperative transmission were summarized and analyzed, and their future development trends and challenges were pointed out.

Extended Abstract
Space-air-ground integrated information network has become a key target of building the six generation (6G) communication system. Compared to radio frequency technology, wireless optical communication has the advantages of large capacity, high data rate and strong anti-interference ability, which makes it becomes an indispensable technology to establish a global seamless coverage network. At present, large amounts of studies focus on improving the performance of Free Space Optical Communication (FSOC) from the physical layer. Research on upper layer key technologies of FSOC networks has focuses on terrestrial or satellite optical networks, while no solutions have been developed for space-air-ground integrated FSOC networks. This paper reviews the construction and standardization status, design factors and key technologies of space-air-ground integrated FSOC networks, and highlights the important challenges for the upper layers. The main points of this paper are summarized as follows: a large number of laser communication experiments have been conducted for intra- and inter-layer links in satellite, stratospheric and terrestrial networks, and many projects such as Iridium system, OneWeb and Hongyan have been built at home and abroad, laying a solid foundation for the construction of the integrated FSOC networks. However, the current standardization documents of FSOC only aim at the physical and data link layers, but remain a gap for the upper layers; in order to provide an accurate underlying model for network algorithm design and protocol optimization, it is necessary to fully understand the characteristics of optical signal transmission by improving the accuracy of atmospheric channel modeling; as an important prerequisite to ensure FSOC link stability, acquisition, pointing and tracking technique requires further reduction in hardware size and complexity, as well as improved performance when the terminal is moving at high speed; topology control, routing, and resource allocation technologies still require significant research investment to match the characteristics of the integrated FSOC networks and to obtain better network performance; since the traditional Transmission Control Protocol (TCP) cannot adapt to high-speed, long-latency, and high packet loss networks, it is necessary to develop specialized transmission protocols or improve existing TCP protocols; FSOC network transmission performance is hampered by FSOC link characteristics, and hybrid transmission methods of FSOC/X should be considered to adapt to diverse application scenarios.

 

Key words: space-air-ground integrated free space optical communication network, channel modeling, acquisition, pointing and tracking(APT), topology control, routing, resource allocation, reliable transmission protocol, microwave cooperative transmission

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