Coding amount estimation method and system for satellite-ground quantum key distribution based on laser echo

The invention provides a laser echo-based satellite-to-ground quantum key distribution coding amount estimation method and system, and the method comprises the steps: estimating the distance of a shielding object and an atmospheric attenuation value on a channel through employing an echo signal reflected after the laser irradiates the shielding object, thereby obtaining a time-varying satellite-to-ground channel attenuation condition which accords with the real condition. Based on the real satellite-ground channel attenuation condition and background noise obtained through simulation, the coding amount in any time period can be accurately estimated according to a coding formula through simulation calculation, so that accurate quantization estimation of coding can be realized in satellite-ground quantum key distribution in accordance with the actual condition. 本发明提出了一种基于激光回波的星地量子密钥分发的成码量估算方法及系统，其中利用激光照射在遮挡物后反射的回波信号，估计遮挡物距离和信道上的大气衰减值，从而获得与真实情况相符的、时变的星地信道衰减情况。基于模拟获得的真实的星地信道衰减情况和背景噪声，可以通过仿真计算，根据成码公式精确估算任意时间段的成码量，