基于调制后向反射器的星地光通信：感知与定位
Modulating Retroreflector-based Satellite-to-Ground Optical Communications: Sensing and Positioning
AI总结：
针对CubeSat重量与功率受限问题，本文建模MRR星地激光链路，提出基于最大似然的初始位置感知、最优束宽优化及两种定位算法，并以误差下界和仿真验证性能。
摘要：
本文聚焦于调制后向反射器（MRR）激光链路的优化设计，以为立方体卫星（CubeSats）建立高速下行链路，同时考虑到这些微小卫星通常面临的重量和功率限制。为此，首先开展了全面的信道建模，考虑了关键的真实信道参数，包括机械万向架误差、快速转向镜角度误差、激光束宽、MRR面积、大气湍流和信道相干时间。据此，推导了接收信号分布的闭式表达式，并利用该表达式提出了一种基于最大似然的方法来感知和估计卫星的初始位置。随后，将感知阶段距离估计误差的分布表示为激光束宽和万向架误差的函数，这使我们能够微调最优激光束宽，以最小化感知时间。此外，利用感知和初始卫星距离估计，提出了两种定位算法。为了比较所提出定位方法的性能，我们获得了定位误差的下界作为基准。最后，通过提供全面的仿真，我们评估了不同参数对所考虑的基于MRR的系统在感知和定位两个阶段性能的影响。
英文摘要：
This paper focuses on the optimal design of a modulated retroreflector (MRR) laser link to establish a high-speed downlink for cube satellites (CubeSats), taking into account the weight and power limitations commonly encountered by these tiny satellites. To this end, first, a comprehensive channel modeling is conducted considering key real channel parameters including mechanical gimbal error, fast steering mirror angle error, laser beamwidth, MRR area, atmospheric turbulence, and channel coherence time. Accordingly, a closed-form expression for the distribution of the received signal is derived and utilized to propose a maximum likelihood based method to sense and estimate the initial position of the satellite. Subsequently, the distribution of the distance estimation error during the sensing phase is formulated as a function of the laser beamwidth and the gimbal error, which enables us to fine-tune the optimal laser beamwidth to minimize sensing time. Moreover, using the sensing and initial satellite distance estimation, two positioning algorithms are proposed. To compare the performance of the proposed positioning method, we obtain the lower bound of the positioning error as a benchmark. Finally, by providing comprehensive simulations, we evaluate the effect of different parameters on the performance of the considered MRR-based system in both the sensing and positioning phases.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
