基于最大似然估计的低轨通信星座分布式时间同步方法研究

doi:10.11959/j.issn.1000-0801.2024161

Abstract

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.

Key words: low earth orbit satellite, distributed satellite system, time synchronization, maximum likelihood estimation

CLC Number:

TN927

Bing YAN, Yafei ZHAO, Yiming FANG, Mugen PENG, Guangrong LIN. Research on distributed time synchronization methods for LEO communication constellations based on maximum likelihood estimation[J]. Telecommunications Science, 2024, 40(6): 60-68.

Figures/Tables 8

参数名	参数值
同步周期 $T b$ /s	10
硬件时钟偏差	$2 × 10 - 11 s t d .$
硬件时钟偏移/ns	$20$ $s t d .$
$ρ η$	0.4
$ρ$	0.4
$ρ v$	0.6
$d k$	$N 2.5 × 10 - 5, 2 × 10 - 9$
卫星数量/颗	12

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Research on distributed time synchronization methods for LEO communication constellations based on maximum likelihood estimation

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