  The real-time routing for satellite communication of the mega-constellations
is being challenged due to the large-scale of network nodes, especially on
devices with limited computation such as onboard embedded systems. In this
paper, a fast routing method is proposed for mega-constellation backbone
networks. Firstly, inspired by the regularity and sparse characteristics of
mega-constellations, the 4-degree percolation theory is proposed to describe
the node search process. Then, dynamic minimum search and mapping methods are
used to narrow down the traversal range. The proposed method performs as well
as the heap-optimized Dijkstra algorithm with less memory space and dynamic
access. The experimental results show that the method proposed in this paper
can significantly reduce routing computation time, especially on the onboard,
edge-computing or other computation-limited devices.
