GNSS Doppler Velocity Estimation Aided by 3D Mapping Database

The recent surge in the development of autonomous vehicles has increased the need for reliable dynamic positioning of road agents in urban areas. Doppler frequency measurement of the global navigation satellite system (GNSS) can provide dynamic information and be used to estimate velocity. However, similar to pseudorange, the accuracy of Doppler frequency is degraded in dense urban areas, due to signal reflections from obstacles, resulting in substantial velocity errors. Existing methods tend to directly exclude non-line-of-sight (NLOS) Doppler frequency, which in turn leads to insufficient measurement numbers. 3D mapping aided (3DMA) GNSS ray-tracing method is commonly used to estimate extra delay from NLOS. The angle of arrival (AOA) of the reflected signal is obtained while tracing the propagation path, which can also be used to simulate NLOS Doppler frequency. Thus, this paper investigates the potential of using NLOS Doppler frequency as a feature for estimating velocity. A novel candidate-based 3DMA GNSS velocity estimation framework is proposed using Doppler frequency to examine the consistency between simulation on each candidate and measurement. Experimental results show NLOS Doppler frequency feature can enhance velocity estimation accuracy, reducing the root-mean-square error of velocity estimation by 46% from 1.06 m/s to 0.57 m/s in dense urban areas.