Acta Geodaetica et Cartographica Sinica ›› 2020, Vol. 49 ›› Issue (1): 1-13.doi: 10.11947/j.AGCS.2020.20190106

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Three multi-frequency and multi-system GNSS high-precision point positioning methods and their performance in complex urban environment

GENG Jianghui, CHANG Hua, GUO Jiang, LI Guangcai, WEI Na   

  1. GNSS Research Center, Wuhan University, Wuhan 430079, China
  • Received:2019-04-16 Revised:2019-08-30 Published:2020-01-16
  • Supported by:
    The National Natural Science Foundation of China (No. 41674033)

Abstract: 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.

Key words: high-precision point positioning, multi-frequency and multi-system GNSS, urban environment, single epoch, wide-lane ambiguity resolution

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