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<p>Due to the influence of phase biases, the carrier phase ambiguities in precise point positioning (PPP) have to be resolved in real value. The estimated phase bias products can be used to achieve ambiguities recovery (AR) solutions in PPP. However, the phase bias products currently available for global users are based on a large and evenly distributed network of ground stations. BeiDou Navigation Satellite System (BDS), due to its regional station deployment, lacks the capability to independently and autonomously estimate global phase bias products. Fortunately, the low earth orbit (LEO) satellite navigation augmentation constellation being developed in China holds the potential to supplement regional ground stations and enable independent and autonomous estimation of global phase bias products. In this paper, we propose an optimized method that combines ground and onboard BDS observations to estimate uncalibrated phase delay (UPD). We evaluate the ability of three LEO constellations, namely Walker24/12/1, Walker60/12/1, and Walker108/12/1, to assist eight regional ground stations in UPD estimation. The results show that all three schemes can obtain a group of wide-lane (WL) and narrow-lane (NL) UPD products with good residual distribution. Among them, the 108 LEO scheme achieves the most stable and optimal residual distribution for NL UPD products, because it ensures that each BDS satellite is tracked by at least five stations, whereas with 24 and 60 LEOs, BDS satellites do not reach 100%. To further validate the feasibility of the UPD estimation method, 138 globally distributed stations are subjected to PPP-AR. The results demonstrate that the 108 LEO scheme yields the best performance after ambiguity fixing. For the East, North, and Up directions, the average convergence times decrease from 35.0, 21.5, and 46.0&#xa0;min to 25.0, 21.0, and 33.8&#xa0;min, respectively, while the positioning accuracy improves from 1.5, 0.8, and 2.0&#xa0;cm to 0.6, 0.5, and 1.4&#xa0;cm. Additionally, the 24 and 60 LEO schemes also show good performance based on statistical analysis. In conclusion, considering timeliness, the 24 LEO scheme can provide UPD products that meet the needs of global users, while for less stringent timeliness requirements, the 108 LEO scheme can achieve the optimal and most stable UPD products.</p>

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Beidou UPD estimation and assessment based on LEO-assisted regional stations observations

  • 期刊论文

  • 发表日期：

    2025年5月13日

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  • Wen Lai,
  • GuanWen Huang,
  • Le Wang,
  • ShiChao Xie,
  • HaoNan She

摘要

Due to the influence of phase biases, the carrier phase ambiguities in precise point positioning (PPP) have to be resolved in real value. The estimated phase bias products can be used to achieve ambiguities recovery (AR) solutions in PPP. However, the phase bias products currently available for global users are based on a large and evenly distributed network of ground stations. BeiDou Navigation Satellite System (BDS), due to its regional station deployment, lacks the capability to independently and autonomously estimate global phase bias products. Fortunately, the low earth orbit (LEO) satellite navigation augmentation constellation being developed in China holds the potential to supplement regional ground stations and enable independent and autonomous estimation of global phase bias products. In this paper, we propose an optimized method that combines ground and onboard BDS observations to estimate uncalibrated phase delay (UPD). We evaluate the ability of three LEO constellations, namely Walker24/12/1, Walker60/12/1, and Walker108/12/1, to assist eight regional ground stations in UPD estimation. The results show that all three schemes can obtain a group of wide-lane (WL) and narrow-lane (NL) UPD products with good residual distribution. Among them, the 108 LEO scheme achieves the most stable and optimal residual distribution for NL UPD products, because it ensures that each BDS satellite is tracked by at least five stations, whereas with 24 and 60 LEOs, BDS satellites do not reach 100%. To further validate the feasibility of the UPD estimation method, 138 globally distributed stations are subjected to PPP-AR. The results demonstrate that the 108 LEO scheme yields the best performance after ambiguity fixing. For the East, North, and Up directions, the average convergence times decrease from 35.0, 21.5, and 46.0 min to 25.0, 21.0, and 33.8 min, respectively, while the positioning accuracy improves from 1.5, 0.8, and 2.0 cm to 0.6, 0.5, and 1.4 cm. Additionally, the 24 and 60 LEO schemes also show good performance based on statistical analysis. In conclusion, considering timeliness, the 24 LEO scheme can provide UPD products that meet the needs of global users, while for less stringent timeliness requirements, the 108 LEO scheme can achieve the optimal and most stable UPD products.