Dianxin kexue (Jun 2024)
Research on distributed time synchronization methods for LEO communication constellations based on maximum likelihood estimation
Abstract
As the rapid deployment of low earth orbit (LEO) mega-constellations and the swift growth of satellite Internet unfolds, distributed satellite systems composed of a large number of LEO satellites become a significant feature of the space-air-ground integrated networks. In satellite networks, low-cost, high-precision time synchronization technology is one of the core technologies.The distributed timing synchronization problem of LEO communication constellations, influenced by the high dynamics and temporally varying topological structures of low orbit satellites was focused on. Considering the communication delay characteristics in the LEO satellite scenario, and addressing the deficiencies in synchronization accuracy and convergence speed of existing methods in dynamic network topologies, a timing synchronization method based on maximum likelihood estimation for LEO satellites was proposed. This method effectively solves the problem of unpredictable random communication delays and asymmetric inter-satellite distances in distributed dynamic networks. The simulation results show that the synchronization error of the time synchronization method based on maximum likelihood estimation is less than 5 ns under the dynamic scenario and topology of LEO satellites.
