Research on the uploading satellites scheduling based on inter-satellite links of GNSS

As an important space infrastructure, Global Navigation Satellite System (GNSS) plays a significant role both in military applications and in economic development. Controlling and managing the GNSS constellation depends on few stations even only one station by dint of inter-satellite links is a international important research field. The ephemeris uploading, which refers to uploading ephemeris from ground station to satellite, is one of the core tasks of GNSS, and it has a significant impact both on the update rate and the age of the ephemeris, therefore influences the precision of the system service. This paper analyzes and compares the process of the ephemeris uploading with and without inter-satellite links of GNSS, and classifies the normal process modes of the ephemeris uploading of GNSS into multi-station-multi-satellite mode and single-station-single-satellite mode. Afterwards, this paper compares the characteristics of the two modes and discusses the advantages and disadvantages of the two modes. Then this paper establishes the process model of the two modes, analyzes the factors of influencing uploading satellites scheduling, and proposes the uploading satellite scheduling rules and algorithms. At last, this paper devises benchmarks for the problem according to the input of the proposed model, obtains uploading satellites and uploading links for the two modes via different selection rules and algorithms, and compares the link details. The research will be instructive to process optimization for the ephemeris uploading of GNSS.