As an important part of BeiDou navigation satellite system (BDS), the BeiDou satellite based augmentation system (BDSBAS) provides single frequency SBAS service, in accordance with the international civil aviation organization (ICAO) standards and recommended practices (SARPs). Detailed models for assessing the accuracy and integrity of SBAS ionospheric corrections as well as satellite ephemeris and clock corrections are introduced. To address the noise amplification in dual frequency ionosphere-free observations, a range domain assessment method is proposed. The performance of BDSBAS was investigated using data from 243 stations of the crustal movement observation network of China (CMONOC) in 2021 and 2023, revealing significant differences between the northern (latitude above 30 degrees north) and southern (latitude below 30 degrees north) regions. With quiet ionosphere, BDSBAS demonstrated a consistent ionospheric correction accuracy of 0.63 to 0.78 m and an average grid ionospheric vertical error (GIVE) integrity of 95.95%. However, with active ionosphere in 2023, the ionospheric correction accuracy in the southern region dropped to 1.56 m, with integrity falling to 87.23%. The satellite ephemeris and clock corrections showed less susceptibility to ionospheric conditions, achieving an accuracy of 0.5 m for the two years. The integrity of the BDSBAS user differential range error (UDRE) parameter was approximately 91%, which was influenced by the UDRE scale factor in message type (MT) 28. The range domain error analysis in 2023 also revealed the characteristics of higher accuracy in the northern region (0.55 m) and lower accuracy in the southern region (1.28 m), with range domain integrity decreasing from 99.71 to 94.62%. In 2021, the 95% positioning error of BDSBAS in horizontal and vertical directions were 1.66 and 2.76 m, respectively, while in 2023, they were 4.04 and 4.18 m. No hazardous misleading information (HMI) events occurred within the two years. However, misleading information (MI) events were recorded during the study period, with the positioning integrity risk being 4.2 × 10−4 in 2021 and increasing to 3.0 × 10−2 in 2023. The MI events were primarily observed at stations in low latitude area. Due to the small protection level, the overall availability for APV-I operation reached 99.9% in 2021, and 96.8% in 2023 with most of the unavailable results were caused by MI events. The performance of BDSBAS service network time (SNT) was also investigated, revealing that the difference between BDSBAS SNT and GPS time (GPST) was maintained within 50 ns for 99.7% of the time.

Single frequency service performance of BDSBAS: models and assessment

期刊论文
发表日期：

2025年4月8日

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Shanshan Chen,
Weiguang Gao,
Min Li,
Biao Jin

摘要

As an important part of BeiDou navigation satellite system (BDS), the BeiDou satellite based augmentation system (BDSBAS) provides single frequency SBAS service, in accordance with the international civil aviation organization (ICAO) standards and recommended practices (SARPs). Detailed models for assessing the accuracy and integrity of SBAS ionospheric corrections as well as satellite ephemeris and clock corrections are introduced. To address the noise amplification in dual frequency ionosphere-free observations, a range domain assessment method is proposed. The performance of BDSBAS was investigated using data from 243 stations of the crustal movement observation network of China (CMONOC) in 2021 and 2023, revealing significant differences between the northern (latitude above 30 degrees north) and southern (latitude below 30 degrees north) regions. With quiet ionosphere, BDSBAS demonstrated a consistent ionospheric correction accuracy of 0.63 to 0.78 m and an average grid ionospheric vertical error (GIVE) integrity of 95.95%. However, with active ionosphere in 2023, the ionospheric correction accuracy in the southern region dropped to 1.56 m, with integrity falling to 87.23%. The satellite ephemeris and clock corrections showed less susceptibility to ionospheric conditions, achieving an accuracy of 0.5 m for the two years. The integrity of the BDSBAS user differential range error (UDRE) parameter was approximately 91%, which was influenced by the UDRE scale factor in message type (MT) 28. The range domain error analysis in 2023 also revealed the characteristics of higher accuracy in the northern region (0.55 m) and lower accuracy in the southern region (1.28 m), with range domain integrity decreasing from 99.71 to 94.62%. In 2021, the 95% positioning error of BDSBAS in horizontal and vertical directions were 1.66 and 2.76 m, respectively, while in 2023, they were 4.04 and 4.18 m. No hazardous misleading information (HMI) events occurred within the two years. However, misleading information (MI) events were recorded during the study period, with the positioning integrity risk being 4.2 × 10⁻⁴ in 2021 and increasing to 3.0 × 10⁻² in 2023. The MI events were primarily observed at stations in low latitude area. Due to the small protection level, the overall availability for APV-I operation reached 99.9% in 2021, and 96.8% in 2023 with most of the unavailable results were caused by MI events. The performance of BDSBAS service network time (SNT) was also investigated, revealing that the difference between BDSBAS SNT and GPS time (GPST) was maintained within 50 ns for 99.7% of the time.