Performance improvement in LEO-to-Ground free space optical communication systems with adaptive distributed frame repetition

We proposed and evaluated the effectiveness of a simple rate control technique of Adaptive Distributed Frame Repetition (ADFR), which achieves both high speed link in the stable condition and suppresses the influence of turbulence-induced fading in the unstable condition. In order to estimate its performance in the LEO-to-Ground link with 10-Gb/s modulation speed, we developed a numerical simulator which enables us to calculate the frame error rate and the throughput under the specific turbulence condition emulated by random phase screens. We confirmed that ADFR can increase the link duration and the capacity by increasing the tolerance to the fading especially in the region of lower elevation angle. In addition, we evaluated its effectiveness through the comparison with the general adaptive rate control, in which the receiver sensitivity can be manipulated in accordance with the link conditions. The results show that ADFR provides similar performances with the sufficient received optical power.