An Adaptive Threshold Estimation for Coarse Synchronization in Transponding Satellite Communication System

In transponding satellite communication (TSC) system, coarse synchronization is the key for the ground station to receive and process inbound signals, which directly affects the sensitivity of signal receiving and detection probability. The power and Doppler effect of the transmitted signal vary from terminals to terminals due to differences in positions, dynamic scenes, antenna status as well as terminal types. Furthermore, the satellite motion is variable, especially the high dynamic LEO(Low Earth Orbit) satellite communication systems in the future, whose satellite antenna beam direction changes rapidly. All these problems bring challenges to the coarse synchronization of ground station in transponding satellite communication system. At present, the ground station coarse synchronization mostly adopts the fixed threshold estimation and CFAR threshold estimation, which are not suitable for the future LEO satellite communication systems. In this paper, an adaptive threshold estimation method for inbounding signals coarse synchronization, which neither changes the framework of transponding satellite communication system nor requires additional resources, is proposed to obtain more stable acquisition sensitivity and increase the detection probability in the dynamic scene. Also, the theoretical analysis and simulations results are presented to verify this method.