Modeling, refinement and evaluation of multipath mitigation based on the hemispherical map in BDS2/BDS3 relative precise positioning
Modeling, refinement and evaluation of multipath mitigation based on the hemispherical map in BDS2/BDS3 relative precise positioning
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DOI：
10.1016/j.measurement.2023.112722
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发表时间：
2023-03
期刊：
影响因子：
5.6
通讯作者：
Zhetao Zhang;Yi Dong;Yuanlan Wen;Yiran Luo
中科院分区：
文献类型：
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作者：
Zhetao Zhang;Yi Dong;Yuanlan Wen;Yiran Luo
在毫米级北斗导航卫星系统(BDS)定位中，多径定位是一个关键的制约因素。由于多径半球面地图(MHM)可以在相对实时和运动学的场景下进行，因此在实际的BDS应用中具有很大的潜力。然而，有限的研究集中在基于第二代区域系统(BDS2)和第三代全球系统(BDS3)的MHM的缓解性能和效率问题上。本文系统地研究了BDS2/BDS3相对精密定位中的MHM问题，包括MHM的建模、求精和评估等问题。具体地说，首先给出了一种严格的带质量控制的MHM建模过程，可以获得高精度和高可靠性的多径校正。其次，在连续11天设计试验的基础上，综合考虑系统、卫星、频率等因素，建立了不同的MHM模型，并进行了综合比较。第三，对MHM模型的定位性能进行了系统的评估，包括模糊度解算、浮点解算和固定解算。结果表明，在MHM模型中，对低仰角的多径改正更为显著，并且由于障碍物的存在，在不同方向的多径效应通常是不同的。MHM模型的行为取决于系统、卫星和频率类型。此外，MHM模型在连续七天内相对稳定。在毫米级定位中应用MHM模型后，可以提高模糊度解算的成功率。浮子溶液在3D方向上可以获得大约700万厘米的改善。对于固定解，MHM模型可以将定位精度提高约13%，特别是在多径比较严重的位置。而且，在考虑精度和效率的平衡时，前一天带有质量控制的统一的MHM方法可以取代精细化的MHM方法。
Multipath is one of the critical constraints in millimeter-level BeiDou navigation satellite system (BDS) positioning. Since multipath hemispherical map (MHM) can be conducted in relatively real-time and kinematic scenarios, it has great potential in real BDS applications. However, limited studies focus on the mitigation performance and efficiency problem based on MHM with the second-generation regional system (BDS2) and third-generation global system (BDS3). In this paper, the MHM is systematically studied in BDS2/BDS3 relative precise positioning, including the issues of MHM about the modeling, refinement, and evaluation. Specifically, at first, a rigorous modeling procedure of MHM with quality control is given, where the high-precision and high-reliability multipath corrections can be obtained. Second, based on a consecutive eleven-day designed experiment, different MHM models considering the systems, satellites, and frequencies are formed and compared comprehensively. Third, the MHM models are systematically evaluated on the positioning performance, including ambiguity resolution, float solution, and fixed solution. The results show that in MHM models, the multipath corrections for low elevation angles are more significant, and the multipath effects are usually different in different directions due to the obstacles. The behaviors of MHM models are dependent on the system, satellite, and frequency types. Besides, the MHM models are relatively stable over seven consecutive days. After applying the MHM models, the success rate of ambiguity resolution can be improved in millimeter-level positioning. Approximately 7 cm improvements can be obtained for the float solution in the 3D direction. The MHM models can improve the positioning accuracy by approximately 13% for the fixed solution especially in locations where the multipath is more severe. Moreover, the unified MHM method of the previous day with quality control can replace the refined MHM method when considering the balance between accuracy and efficiency.