基于自适应环境感知与融合的高隐蔽卫星通信技术

To improve the anti-perception capability of the ground-to-space link of covert satellite communications systems, in this proposal we present a new strategy called “adaptive environment awareness and fitting-in”, which means before start a transmission, the ground terminal first performs spectrum sensing and chooses a few environmental signals as “shelters”. By overlapping its own radiating signal with the shelters, the ground terminal for covert satellite communications may hide itself from the neighboring hostile detectors. For the ease of implementing “adaptive environment awareness and fitting-in”, we design in this proposal a new multicarrier transmission scheme named Non-Uniform Carrier Aggregation Deep Spread Spectrum (NUCA-DSS), which is very suitable to be used for covert communications as it is capable of spreading its signal over a large bandwidth and reducing the radiating PSD down to an extremely low level, both at reasonable hardware cost. Moreover, one may have considerable freedom in choosing the physical parameters for NUCA-DSS, and this in turn allows sufficient flexibility for various spectrum overlapping patterns with the shelters. In this backcloth, we will look into a series of scientific topics, such as multiple outlier detection under non-uniform, time variant background, the analysis of the relationship between the spectrum overlapping pattern and the anti-perception improvement as well as the transmission performance degradation, and how to make the optimum tradeoff. The design and performance analysis of the NUCA-DSS receiver in the presence of strong noise, interference and Doppler effect will be studied, too. In addition to the theoretical research, we shall pursue implementation details. Particularly, we will build a prototype for the space-borne NUCA-DSS receiver and test it under various scenarios. It is our hope that through this project we can find a new path for enhancing the anti-perception ability of the covert satellite communications system. We also hope to extend the general Signal Detection and Estimation Theory and the Receiver Design and Analysis Theory to new applications and signal types.

针对隐蔽卫星通信系统星地上行链路抗侦测能力不足的问题，本项目提出自适应电磁环境感知与融合的方法，即地面终端选择周边环境电磁波信号作为“掩体”，并使其发射信号与掩体适度频谱重叠，达到自我隐蔽的效果；为此，设计非规则载波聚合深度扩频（NUCA-DSS）作为传输波形。NUCA-DSS信号有利于实现超宽带扩频和超低功率谱密度，本身具备强抗侦测能力；且其物理层参数自由度大，便于进行各种形式的频谱重叠。以此为背景，本项目拟解决时变非均一噪声背景下多个频谱突出物的稳健快速检测、频谱重叠对侦测概率和接收机差错率的影响规律分析，星地链路隐蔽性和通信质量最优权衡、复杂电磁环境下NUCA-DSS信道估计和接收机设计等科学问题；在此基础上突破关键技术，并进行演示验证；通过本项目的探索，有望为星地隐蔽传输开辟一条新思路，也有望从新使用场景和新信号形式的角度出发，丰富检测与估计、接收机设计与分析等领域的现有理论成果。

针对隐蔽卫星通信系统星地上行链路抗侦测能力不足的问题，本项目提出自适应电磁环境感知与融合的方法，即地面终端选择周边环境电磁波信号作为“掩体”，并使其发射信号与掩体适度频谱重叠，达到自我隐蔽的效果；为此，设计非规则载波聚合深度扩频（NUCA-DSS）作为传输波形。NUCA-DSS信号有利于实现超宽带扩频和超低功率谱密度，本身具备强抗侦测能力；且其物理层参数自由度大，便于进行各种形式的频谱重叠。以此为背景，本项目解决了时变非均一噪声背景下多个频谱突出物的稳健快速检测、频谱重叠对侦测概率和接收机差错率的影响规律分析，星地链路隐蔽性和通信质量最优权衡、复杂电磁环境下NUCA-DSS信道估计和接收机设计等科学问题；在此基础上突破关键技术，进行了演示验证；通过本项目的探索，为星地隐蔽传输开辟一条新思路，并从新使用场景和新信号形式的角度出发，丰富了检测与估计、接收机设计与分析等领域的现有理论成果。在2019-2022四年间，本项目团队开展的研究工作取得了丰硕的研究成果，发表论文5篇，获批国家技术发明专利19项。相关研究成果支持本研究团队获得2021年度中国电子学会技术发明一等奖1项。

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