3D Digital Track Map-based GNSS NLOS Signal Analytical Identification Method

The dependability of the train localization based on Global Navigation Satellite System (GNSS) is the fundamental for the railway localization applications. In railway stations and similar harsh environments, skyscraper and railway station ceilings have created obstacles to the reception of GNSS signals. Multipath and non-line-of-sight (NLOS) signals have a strong influence on positioning accuracy. 3D digital track map aided localization can identify the NLOS signal caused by obstacles. Then the accuracy and dependability improvement NLOS signal identification analytical method can be applied. This paper proposes a NLOS signal identification analytical method based on 3D digital track map involving a 3D map model and ray-tracing algorithms to identify the propagation trajectory of the GNSS signal especially the NLOS signals, then the NLOS correction method can be applied. Based on the 3D digital track map, the LOS / NLOS signal identification is realized by ray-tracing. This paper proposes a hypothesis-based NLOS signal correction model applied to correct pseudorange. The least square estimation (LSE) algorithm is used to satellite position before and after data correction separately. The results of comparative analysis show that the NLOS signal identification analytical method is effective.