Analysis on Performance of BDS/GPS Fusion Pseudorange Positioning with ISB and Its Influence on DOP

The Global Navigation Satellite System (GNSS) user will benefit a lot from the multi-system fusion positioning in availability, accuracy and reliability. However, the Inter-System Bias (ISB) may weaken the performance of multi-system, especially for single point positioning applications. In this paper, the BDS/GPS (Beidou Satellite Navigation System; Global Positioning System) fusion pseudorange positioning model with the ISB estimation is presented. With the principle of Bayesian estimation, the influence of ISB on the function model is evaluated by analyzing the Generalized Dilution of Precision (G-DOP) factor. A set of measured BDS and GPS observations is used to test and verify the aforementioned models. The result demonstrates that the ISB is ubiquitous and the fusion model with ISB estimation performs well since the fusion positioning accuracy is improved. As an additional parameter, the ISB will cause a deterioration in G-DOP. The priori information of ISB can be utilized to reduce its impact, especially when the amount of observed navigation satellites is not enough.