An Asynchronous Observation Positioning Algorithm Based on Factor Graph Optimization

Broadcasting integrated signal of communication and navigation in low earth orbiting (LEO) broadband constellation to achieve the navigation augmentation is an existing trend. Considering the needs of communication services, the integrated signal generally has burst characteristics, and the receiver only receives the signal from the satellite in some specific time slots, and the observation has obvious asynchronous arrival characteristics. Such asynchronous arrival observations are quite different from the synchronous observations obtained by receiving the continuous navigation signals broadcast by the existing GNSS satellites, which will lead to many problems if using the traditional positioning method. Combining the characteristics of asynchronous observations, this paper proposes an asynchronous observation positioning algorithm based on factor graph optimization (FGO), which can use asynchronous observation in multiple epochs for joint estimation to reduce positioning error. Simulation shows that the positioning algorithm based on FGO can effectively improve the positioning accuracy compared with the traditional method.