High-precision applications, such as intelligent transportation and automated driving in urban environment, require a dynamic positioning accuracy at decimeter to centimeter level. However, GNSS performance (such as availability and positioning accuracy) in urban environments is strongly degraded by man-made and natural objects that obstruct satellite signals. Taking advantage of the available multi-frequency and multi-system GNSS (GPS/BDS/Galileo/QZSS) data, we adopt the new single-epoch PPP wide-lane ambiguity fixing method (PPP-WAR) for vehicle dynamic positioning. It is compared with the traditional PPP method and wide-area pseudorange enhanced precision positioning method in three typical urban environments with different complexity, including a road in metropolitan area, a narrow road in small town and an open road in industrial area. The integrity of triple-frequency GNSS data is currently up to 94% in urban area, which assures that single-epoch PPP-WAR method is applicable in complex urban area. It's shown that a positioning accuracy of 0.41 m in the horizontal direction is achieved using the single-epoch PPP-WAR method in the narrow road in town with the threshold of 3.0 m, which satisfies the accuracy requirement at decimeter level. The accuracy is largely improved by 53.9% and 21.2% compared with those of wide-area pseudorange enhanced precision positioning solutions and traditional PPP solutions, respectively. The availability of three methods in metropolitan area is higher than 70%, as well as more than 90% in small town and industrial area. The availability of PPP-WAR and traditional PPP can still reach ~70% with a strict threshold of 0.5 m. Four typical features (i.e. tunnels, crossovers, street trees and skyscrapers) in urban environment have the least impact on the performance of single-epoch PPP-WAR among the three methods. In sum, single-epoch PPP-WAR method has the best performance in complex urban environment with more obstructions, while traditional PPP method is the best in open urban environment with less obstructions.

引用格式如下：

Geng J, Chang H, Guo J, Li G, Wei N* (2020) Three multi-frequency and multi-system GNSS high-precision point positioning methods and their performance in complex urban environment