Optimizing Spatial Acquisition in Inter-Satellite FSO Links Under Beam jitter

Abstract

The acquisition system is a key element in intersatellite free-space optics (FSO) links. Because satellite vibrations cause the scanning beam to jitter, making the acquisition process both challenging and time-consuming, minimizing acquisition time is crucial for the rapid establishment of an FSO link. In this paper, we present an optimization framework aimed at minimizing acquisition time while maintaining a predefined failure probability threshold. The optimization problem considers the total available power, the amount of overlap between the scanning beams (overlapping factor), and the beamwidth of the scanning beam. Additionally, we incorporate a weighting parameter to account for the varying power costs associated with adjusting the beamwidth and the overlapping factor. To solve this non-convex and NP-hard problem, we utilize an iterative successive convex approximation-based algorithm. When the cost of increasing laser power is high, the results show that as jitter variance increases, the optimal overlapping factor must also increase to maintain the acquisition success probability. Simultaneously, the beamwidth slightly decreases to adhere to power constraints. On the other hand, when the cost for increasing laser power is low, the optimal strategy involves maximizing the beamwidth and increasing the overlapping factor to mitigate jitter effects.