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<p>The Galileo high accuracy service (HAS) is now available to users worldwide for precise point positioning (PPP). PPP ambiguity resolution (AR) can further improve precise positioning performance. To date, few studies have focused on PPP AR based on HAS products at the preliminary stage (Phase 1). In this study, we first obtained the HAS precise satellite orbit and clock products by decoding HAS correction data from March 11 to 17, 2023. Then the wide-lane (WL) and narrow-lane (NL) fractional cycle biases (FCB) were estimated using HAS products while the real-time CNT products from Centre National D'Etudes Spatiales (CNES) were also used for comparison. It is noted that only Galileo FCB was estimated, although HAS provided corrections for both GPS and Galileo systems, which aim to prove the efficiency of Galileo-only PPP AR. Afterward, the self-estimated FCBs were evaluated by the posterior residuals using over 160 MGEX stations. Moreover, performance comparison with respect to geographic location as Galileo HAS provides different services to different areas is also conducted. The stations were grouped into two areas, i.e., HAS service area and non-service area. We found that it is difficult for stations outside HAS service area to achieve Galileo HAS PPP AR using the current HAS product due to the poor quality of HAS-NL FCBs. Finally, we selected 20 testing stations to evaluate the HAS and CNT PPP AR performance using Galileo system under static and simulated kinematic situations in HAS service area. For static testing, the results show that the average improvement for fixed solution of HAS was 28.7%, 12.2%, 13.5%, 20.7% and 16.2% in the east, north, up, 2D and 3D directions, respectively, while that of CNT was 39.6%, 29.8%, 19.9%, 37.3% and 26.0%, respectively. In the simulated kinematic testing, the results show that the average improvement for fixed solution of HAS was 12.3%, 13.0%, 5.7%, 12.6% and 7.6% in the east, north, up, 2D and 3D directions, respectively, while that of CNT was 8.2%, 6.1%, 3.3%,7.1% and 4.6%, respectively. In addition, we found that the fixed solutions of HAS from stations located in core areas show better improvement. The above results show that PPP AR for Galileo system can be performed in HAS service area using the HAS product in Phase 1. However, the successful fixing of ambiguity is time-consuming. This issue may be addressed in subsequent phases of HAS products (Phase 2) as well as by processing the ambiguity of both GPS and Galileo together.</p>

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Performance evaluation of Galileo high accuracy service for PPP ambiguity resolution

  • 期刊论文

  • 发表日期：

    2025年4月20日

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  • Guorui Xiao,
  • Zhengyang Xiao,
  • Peiyuan Zhou,
  • Changjian Liu,
  • Haopeng Wei,
  • Peigong Li

摘要

The Galileo high accuracy service (HAS) is now available to users worldwide for precise point positioning (PPP). PPP ambiguity resolution (AR) can further improve precise positioning performance. To date, few studies have focused on PPP AR based on HAS products at the preliminary stage (Phase 1). In this study, we first obtained the HAS precise satellite orbit and clock products by decoding HAS correction data from March 11 to 17, 2023. Then the wide-lane (WL) and narrow-lane (NL) fractional cycle biases (FCB) were estimated using HAS products while the real-time CNT products from Centre National D'Etudes Spatiales (CNES) were also used for comparison. It is noted that only Galileo FCB was estimated, although HAS provided corrections for both GPS and Galileo systems, which aim to prove the efficiency of Galileo-only PPP AR. Afterward, the self-estimated FCBs were evaluated by the posterior residuals using over 160 MGEX stations. Moreover, performance comparison with respect to geographic location as Galileo HAS provides different services to different areas is also conducted. The stations were grouped into two areas, i.e., HAS service area and non-service area. We found that it is difficult for stations outside HAS service area to achieve Galileo HAS PPP AR using the current HAS product due to the poor quality of HAS-NL FCBs. Finally, we selected 20 testing stations to evaluate the HAS and CNT PPP AR performance using Galileo system under static and simulated kinematic situations in HAS service area. For static testing, the results show that the average improvement for fixed solution of HAS was 28.7%, 12.2%, 13.5%, 20.7% and 16.2% in the east, north, up, 2D and 3D directions, respectively, while that of CNT was 39.6%, 29.8%, 19.9%, 37.3% and 26.0%, respectively. In the simulated kinematic testing, the results show that the average improvement for fixed solution of HAS was 12.3%, 13.0%, 5.7%, 12.6% and 7.6% in the east, north, up, 2D and 3D directions, respectively, while that of CNT was 8.2%, 6.1%, 3.3%,7.1% and 4.6%, respectively. In addition, we found that the fixed solutions of HAS from stations located in core areas show better improvement. The above results show that PPP AR for Galileo system can be performed in HAS service area using the HAS product in Phase 1. However, the successful fixing of ambiguity is time-consuming. This issue may be addressed in subsequent phases of HAS products (Phase 2) as well as by processing the ambiguity of both GPS and Galileo together.