信息时效约束下的深空测控通信传输技术研究

In deep space exploration, the long-delay and low-reliability transmission over the ultra-long distance and high dynamic channel has caused the objective problem of "poor information timeliness" in deep space TT & C. In the future, this poor-timeliness problem will become even worse when deep space exploration goes into more distant and more complex environments. However, for tasks such as high-precision teleoperation and manned space-exploration communications, the demand for controllable and even augmented information timeliness will become more urgent. In response to this fundamental issue, this project aims to build a theoretical framework for the analysis of deep space information timeliness and propose a series of transmission technologies to provide controllable and augmented information timeliness. Systematic researches on the transmission mechanisms of deep space TT & C have been planned. The research items are as follows. The starting work is to establish a quantitative and reasonable characterization model for the deep space information timeliness, and then all the followed research issues will be carried out under the guidance of the general ideal of hierarchical and multi-scale adaptive transmission. By means of double-layer error control, cross-layer and cross-module joint optimization, dynamic adaptive transmission and so on, transmission mechanisms that can achieve optimized trade-off between the information freshness and reliability, as well as between the efficiency and reliability under the deep space environment, are investigated, and all the mechanisms are systematically integrated to eventually realize the controllable and augmented information timeliness for deep space communications. The project provides a positive and basic idea for the handling of the poor information-timeliness problem in deep space exploration, and the related achievements can provide theoretical and technical reference for the design of the future deep space TT & C systems.

深空探测中，超远程高动态信道条件下的长时延、低可靠传输造成了深空测控通信“信息时效差”这一客观问题。在未来更远距离、更复杂环境下的深空探测中，信息时效问题愈发突出，而以高精密遥操作、载人探测通信等为代表的业务对可控信息时效与增强信息时效的需求却更加迫切。针对这一根本问题，本项目以明晰深空信息传输的时效约束机理、建立具有可控和增强信息时效的传输技术体制为目标，系统展开信息时效约束下的深空测控通信传输技术研究，包括：以建立定量、合理的信息时效多维表征模型为切入，以分层多尺度适配传输为总体思想，通过双层差错控制、跨层跨模块联合优化、动态自适应传输等方法，深入探索深空环境下信息传输的新鲜度和可靠性之间、有效性和可靠性之间的折衷优化机理，综合实现深空通信信息时效的稳定可控与优化增强。本项目为深空探测信息时效问题的应对提供了一种积极的、基础性思路，相关成果可为未来测控通信系统的设计提供理论与技术参考。

为突破深空探测信息传输所面临的信道复杂时变、损耗大、时延长、上下行链路非对称、发收节点资源非对称等多重制约，本项目以明晰深空通信信息传输的时效约束机理、建立具有可控和增强时效的传输技术体制为目标，设计出了高时效的深空探测信息传输技术体制，为深空通信中高效高可靠信息传输提出综合解决方案。截至2022年底，各研究计划要点全部执行，预期目标达到。..项目所取得的主要成果包括：(1) 以明晰深空通信信息时效约束机理为目标，综合考虑比特/符号级以及语义/效用级信息时效，建立了合理的、定量的深空信息时效多维表征模型。(2) 以保障深空通信可控信息时效为目标，综合考虑分组层和底层信道编码面向的信道特性，提出了底层信道编码与上层分组纠删编码相结合的双层差错控制传输体制，深入研究了可匹配上下行业务与资源约束特点的高增益信道编译码技术。(3) 以深空通信增强信息时效为目标，基于双层差错控制体制，研究了双层编码的联合冗余分配模型及方法，通过不同层面技术模块之间的纵向跨层联合优化协作实现业务所需的可靠传输。(4) 深入研究了近地（星球）空间通信场景的HARQ适用条件，并通过设计HARQ冗余配比优化方案实现信息高时效传输。（5）以提升深空通信信息时效裕度为目标，从业务层面研究深空增强信息时效的传输控制优化及自适应传输策略，提出了面向近地（星球）通信的fast IR-HARQ传输策略，通过信道估计减少译码和反馈，提升系统的时效裕度；针对多用户远程通信场景，提出了等待-聚合传输方案，将多个信源的数据包编码形成长码传输，提升远距离通信场景的信息时效；针对深空通信多用户接入场景，探讨了结合本地信息的动态接入方案，运用已知本地信息动态调整接入概率，从而获得最优的分布式接入策略。