面向GNSS星间通信的网络编码基础理论研究

ISLs play an important role in the global navigation satellite system (GNSS), such as improving the precision of orbit determination and time synchronization accuracy, advancing the management level and enhancing the control capability for constellation of independent operation. The forefront research in the field of space technology has forced on the needs for both global satellite navigation system inter-satellite measurement and inter-satellite link communication. Until now, the four GNSS systems have adopted or plan to use a narrow or a mixed beam structure in order to meet the needs of inter- satellite measurement as well as the inter-satellite communications capacity. As the result, they compel to increase the entire star load excessively, the system complexity extremely and the cost enormously. This project using network coding paves an innovative way to resolve the inter-satellite communication problem while satisfying inter-satellite measurement under the wide beam structure. This novel approach can not only reduce the load of entire star the system complexity and cost, but also easily deploy in the future. The project will study the fundamental theoretical framework, such as GNSS wireless network coding model which satisfies the navigation inter-satellite measuring and the maximum capacity of this network. The basic application theory will be studied as well, such as the network coding and decoding methods for GNSS of large-scale high-dynamic and variable delay. The contributions of this work provide theoretical and technical support for inter-satellite efficient communications in future GNSS, and promote the development and advancement of network coding theory.

星间链路在全球卫星导航系统（GNSS）中承担着重要角色，如提高精密定轨和时间同步精度、提高星座控制管理水平及增强星座自主运行能力。解决全球卫星导航系统星间链路测量与通信需求问题一直是航天领域的研究热点和前沿。目前国内外均采用窄波束或宽波束加窄波束的混合体制解决满足星间测量需求下的星间通信问题，但付出了整星负载增加、系统复杂度和成本提升的巨大代价。本项目提出利用网络编码技术解决宽波束体制下满足星间测量需求的星间通信问题，不仅能降低整星负载、系统复杂度和成本，而且易于未来星间链路部署。本项目将研究符合网络编码的导航星座星间测量通信模型和大时空尺度下网络编码最大容量等基础理论问题，及导航星座高动态大尺度可变时延情况下网络编码的编译码方法的应用基础理论问题，为未来GNSS星间高效通信提供理论和技术支持，并推动网络编码理论的发展和进步。

星间链路是全球卫星导航系统现代化的重要标志，在导航系统中有着重要的功能。随着导航卫星自身健康遥测信息量提高、导航星座控制数据的注入频度增加以及导航卫星支持的星间扩展数据传输任务量的增加，导航系统必然面临着更高的星间通信容量的需求。单纯采用窄波束体制将使卫星负担过重，而宽波束和窄波束混合体制虽在一定程度上减轻了卫星负担，但卫星整体设计更加复杂甚至难以承受。. 本项目基于GNSS的宽波束星间测量与通信体制，利用网络编码技术提高导航星座网络数据的吞吐量，在不增加宽波束星间链路硬件设备的基础上，有效解决导航星间链路承担的逐渐增加的通信任务。在理论方面，课题证明了星间动态网络的线性网络编码存在性、时序动态星间网络的线性网络编码存在定理、双向中继模型的编码节点队列系统概率特征分析、三条输入信息流的异步网路编码队列系统概率特征分析等基础数据问题，是在队列理论方面对网络编码基础理论的补充和完善。在应用方面，课题创新性的提出了基于网络编码的GNSS星间高效通信算法，在不改变硬件基础架构的前提下，通过算法实现了对宽波束星间通信效率倍数级的提高。. 本项目研究成果推动网络编码基础理论的发展和进步，是解决全球卫星导航系统星间链路宽波束测量需求与中高速率通信需求矛盾的一种有效途径，为网络编码基础理论在GNSS星间高效通信提供理论和技术支持。课题的研究成果具有重要的应用价值和推广空间。