Evaluation for Vehicle Positioning in Urban Environment Using QZSS Enhancement Function

In this paper, we have evaluated the performance and availability enhancement of Quasi-Zenith Satellite System (QZSS) in urban environments. In urban environments, QZSS can be expected to be fairly effective because of the high elevation angle of satellite and enhancement functions. Therefore, we conducted performance and availability enhancement evaluation tests to verify thus. In performance enhancement evaluation test, in order to evaluate the improvement of GPS accuracy by L1 Submeter-class Augmentation with Integrity Function (L1-SAIF) broadcasted by QZSS satellite, we compared the positioning errors of only GPS positioning and L1-SAIF positioning in open sky environment. In availability enhancement evaluation test, we performed the static and kinematic observation test. In static observation test, in order to evaluate the improvement of GPS accuracy by availability enhancement, we observed GPS and QZSS statically in narrow-sky environment. And we compared the positioning errors of only GPS positioning and positioning using availability enhancement. In kinematic observation test, in order to evaluate the availability of QZSS based on the visibility of QZSS satellite in urban environment, we observed QZSS and SBAS from moving vehicle. And we compared the visibility of QZSS and SBAS satellites. From these evaluation tests, it was confirmed that the performance and availability enhancement of QZSS have high availability and effectiveness.