This paper theoretically studies the design and performance analysis of the reliable satellite-based quantum key distribution (QKD) over free-space optics channel. The proposed QKD system is based on the optical quadrature phase-shift keying (QPSK) modulation and the dual-threshold/heterodyne detection (DT/HD) receiver that helps to reduce quantum bit error rate (QBER) and improve the receiver sensitivity. In addition, a key retransmission scheme is also designed to enhance the reliability of the proposed QKD system. Performance of the key transmission is analyzed in terms of QBER and the probability of sifted key, taking into account the impacts of free-space path loss, atmospheric attenuation, beam spreading loss, atmospheric turbulence, and receiver noise. In addition, we newly develop an analytical framework by using the 3-D Markov chain model that allows us to investigate the key loss rate (KLR) performance at the link layer. Numerical results quantitatively show that our proposed satellite-based QKD system can offer significant performance improvement over the conventional ones.

本文从理论上研究了基于自由空间光学信道的可靠星基量子密钥分发(QKD)的设计和性能分析。所提出的 QKD 系统基于光学正交相移键控 (QPSK) 调制和双阈值/外差检测 (DT/HD) 接收器，有助于降低量子比特误码率 (QBER) 并提高接收器灵敏度。此外，还设计了密钥重传方案以提高所提出的 QKD 系统的可靠性。从QBER和密钥筛选概率的角度分析密钥传输的性能，同时考虑了自由空间路径损耗、大气衰减、波束扩展损耗、大气湍流和接收机噪声的影响。此外，我们通过使用 3-D 马尔可夫链模型新开发了一个分析框架，允许我们研究链路层的密钥丢失率 (KLR) 性能。数值结果定量表明，我们提出的基于卫星的 QKD 系统可以提供比传统系统显着的性能改进。