星间光通信系统中多样化波前畸变的建模及其影响分析

Inter-satellite optical communication systems are regarded as the foundation of future space-ground integrated network which is characterized by high speed, large capacity and broad coverage. However, the optical antennas exposed in outer space will be affected by complicated factors and result in the occurrence of diversified wavefront distortions. These concerned distortions, inevitable and of various shapes, may cause the degradation of communication performance and even lead to the break of communication link. For the optimization of optical system performance as well as making effective compensation, this project focuses on the modeling of diversified wavefront distortions via wavelet method, based on which how distortions affect system performance can be analyzed quantitatively. Firstly, optimal wavelet basis functions are selected for the modeling of distortions where the mapping of wavelet factors and physical parameters is given. Secondly, on the basis of the proposed model, the quantitative relations are established between wavelet factors and mutual misalignment as well as communication bit error rates under different modulations. Finally, the influence to tracking and targeting performance is discussed along with the influence to communication performance under different modulations. The theoretical results will be verified via the simulation platform. This project performs research on modeling and influence analysis of diversified wavefront distortions from a new viewpoint, and the results will make sense to performance guarantee of inter-satellite optical communication systems in both theoretical and practical aspects.

星间光通信系统是构建高速率、大容量、广覆盖面的天地一体化通信网络的基础。然而，系统中暴露在外太空的光学天线由于受到复杂因素的影响，不可避免地会产生形状千变万化的多样化波前畸变，从而导致激光通信链路稳定性下降，甚至引起链路的中断。本项目面向星间光通信系统，围绕系统中的多样化畸变，利用小波方法展开畸变建模及其对系统性能影响研究，为优化光学系统、提出有效的补偿方法打下基础。首先，选取最优小波基函数对多样化波前畸变进行建模，给出小波模型中各参数与现实系统中畸变形状的对应关系；其次，建立小波模型参数与系统相互对准偏差及不同调制方式下通信误码率之间的量化关系。最后，研究多样化畸变对系统瞄准、捕获性能以及不同调制方式下通信性能的影响，并进行仿真验证。本项目从新的思路出发研究多样化波前畸变的建模及其影响分析，其结果有望为我国未来星间光通信系统的性能保障提供可靠的理论依据与可行的技术支撑。

卫星通信网络具有体积小、重量轻、功耗小、抗干扰、数据传输率高而且保密性好等诸多优点，被认为是建立高速率、大容量、广覆盖面的全球通信网络必不可少的重要手段；然而噪声等随机因素的存在会导致通信链路性能下降，极端情况下甚至引起通信的中断。本项目围绕噪声环境下卫星通信网络中多样化畸变的建模、通信网络的拥塞检测及通信网络的鲁棒稳定性、大气湍流对通信网络链路性能影响分析等方面展开研究，给出了非高斯噪声下多样化畸变的小波表征及最优小波基选取方法，非高斯噪声环境下通信网络稳定的充分条件；提出了高斯噪声环境下通信网络最优状态估计及最优遗忘因子计算方法；量化分析了大气湍流对接收信号衰减特性和平均误码率的影响，并给出了接收端最佳接收孔径以实现最低误码率。本项目提出的噪声环境下通信网络畸变建模及性能量化分析方法，为提高卫星通信网络性能提供了可靠的理论依据和可行的技术方案。