A Precision Clock Synchronization Method of Satellite Constellation Network Based on IEEE 1588 Protocol

With the rapid application of large-scale low-orbit constellations, precision clock synchronization of satellite constellation network has become an important issue. The traditional method, relying on GNSS timing service, has limited accuracy and is difficult to improve, and it is also easily unavailable in interference environment. It has become an inevitable trend to build precision clock synchronization through inter-satellite links in the constellation network, to meet the needs of distributed collaboration and signal-level coherent synthesis for distributed space systems. The IEEE 1588 precision clock synchronization protocol, used in terrestrial wired networks, is an excellent protocol, and it provides a useful reference for the design of satellite constellation network clock synchronization. Based on the transparent clock mechanism of the IEEE 1588 protocol, this paper builds a clock synchronization system for satellite constellation wireless network, and a precision time-frequency transfer mechanism for constellation network is proposed. Theoretical analysis and numerical simulation of synchronization performance are also carried out. The results show that the synchronization performance of the farthest clock of the constellation network is closely related to the inter-satellite distance and the relay hops, and it points out the optimal clock synchronization method under the condition of a certain transmission power.