Research on Global Navigation Satellite System (GNSS) Autonomous Navigation Technology Based on Inter Satellite Links (ISL)

Global Navigation Satellite System (GNSS) autonomous navigation technology based on Inter Satellite Links (ISL) is one of the most important subsystem in GNSS. GNSS with an autonomous navigation of satellite constellation can obtain a higher system performance and the system viability without the control and support on the ground stations. Up to now, the autonomous technology based on ISL of GNSS has not been operated perfectly. In this paper, we do some research on Global Navigation Satellite System (GNSS) autonomous navigation technology based on Inter Satellite Links (ISL). Geometry model and geometry description of inter satellite links of GNSS is set up in geocentric inertial frame, especially the model of two satellites selected randomly with the same orbit height. The design and research on constellation topology are made with 27/3/1 Walk constellation model designed for the related simulation in this paper. The max visual distance and inter satellite distance among different orbit height in ISL are studied and analyzed, such as Low Earth Orbit (LEO), Medium Earth Orbit (MEO), Geosynchronous Earth Orbit (GEO) and GPS satellites. The visibility of satellites in GNSS constellation is discussed and simulated in this paper. The antenna pointing is modeled and the ISL parameters with antenna pointing error introduced are analyzed. Based on which, autonomous timing synchronization methods and autonomous ephemeris updating technology are studied in this paper, such as the stabilization of atomic clock frequency, equation of state of clock system, inter satellite two-way pseudo-range equation, autonomous timing synchronization Kalman filtering equation and satellite orbit state equation, etc.