Ray-Tracing Correction for GNSS Velocity Estimation Using Doppler Frequency: A Feasibility Analysis
Liyuan Zhang, Hoi‐Fung Ng, Guohao Zhang, Li‐Ta Hsu
Abstract
Accurate positioning from the global navigation satellite system (GNSS) is critical for various civil applications, like location-based services and intelligent transportation systems. GNSS Doppler frequency can provide reliable velocity estimation to improve positioning performance. Unfortunately, the quality of Doppler frequency measurements can be significantly degraded in urban canyons. This is due to the non-line-of-sight (NLOS) receptions altering the incoming signal direction and its dynamic characteristic. Thus, correcting the NLOS error on Doppler frequency is essential for the velocity as well as position estimation in urban canyons. The 3D mapping aided (3DMA) GNSS is a promising technique for NLOS error correction. Its effectiveness on pseudorange measurements has been well proven. However, its feasibility on Doppler frequency correction has not been investigated yet. Therefore, this paper first verifies the feasibility of ray-tracing in modelling Doppler frequency. Then, an urban Doppler frequency assessment is conducted. Finally, the effectiveness of ray-tracing in correcting velocity estimation accuracy is evaluated. The assessment and evaluation assessment are conducted via experiments in both open-sky and urban areas. Results demonstrate ray-tracing has an excellent capability in modelling the NLOS Doppler frequency, which reduces the corresponding measurement error by 62.8% in average and the root-mean-square of velocity estimation error by 51.92%.