3D Mapping Aided GNSS Positioning Using Doppler Frequency for Urban Areas

The performance of global satellite navigation system (GNSS) positioning is severely degraded in dense urban areas because of the signal reception induced by obstacles. Doppler frequency measurement can provide dynamic information and act as a constraint during positioning. However, similar to pseudorange, the accuracy of Doppler frequency degrades, due to reflection, leading to unsatisfactory positioning performance. 3D mapping aided (3DMA) GNSS ray-tracing method is commonly used to estimate extra delay from NLOS or multipath receptions. The incoming direction and reflecting point of the NLOS signal are obtained while tracing the propagation path. Therefore, ray-tracing can also be used to model non-line-of-sight (NLOS) Doppler frequency. However, existing methods tend to avoid using the NLOS Doppler rather than applying ray-tracing to improve positioning. Thus, this paper first investigates the potential of using NLOS Doppler frequency as a feature for relative positioning. Then, the 3DMA GNSS framework is extended on Doppler frequency for relative positioning. Experimental results show that the relative positioning performance of Doppler frequency matching is significantly degraded, but the 3DMA GNSS one has the potential to maintain the relative positioning performance in urban areas.