一种基于双差多普勒频移并具有LEO卫星星历误差校正能力的定位框架
A Double-Difference Doppler Shift-Based Positioning Framework with Ephemeris Error Correction of LEO Satellites
AI总结：
针对LEO机会信号定位中星历误差、长基线和时钟不同步导致的多普勒测量偏差，提出3DPose双差多普勒定位框架及星历误差校正算法，三维定位误差平均降低90%。
摘要：
在利用低地球轨道（LEO）卫星的机会信号（SOPs）进行定位时，由两行轨道根数文件得到的星历数据会随时间引入不断增大的误差。为处理错误测量，在对用户终端（UT）进行定位时，通常会使用一个位置已知的额外基准接收机来补偿星历误差的影响。然而，对于长基线（即基准接收机与UT之间的距离）而言，这种方法并不充分，因为它无法充分校正由星历不准确引起的多普勒频移测量误差，从而导致定位性能下降。此外，基准接收机与UT之间缺乏时钟同步，进一步加剧了多普勒频移测量误差。为应对这些挑战，我们提出了一种鲁棒的基于双差多普勒频移的定位框架，命名为3DPose，用于处理基准接收机与UT之间的时钟同步问题以及长基线导致的定位性能退化。所提出的3DPose框架利用双差多普勒频移测量来消除时钟同步问题，并引入一种新颖的星历误差校正算法，以在长基线情况下提高UT定位精度。该算法专门刻画并校正由错误星历数据引起的多普勒频移测量误差，重点关注切向方向上的卫星位置误差。为验证所提框架的有效性，我们在三种不同场景下进行了对比分析，将其性能与现有差分多普勒定位方法进行对照。结果表明，与现有差分多普勒方法相比，所提出的3DPose框架在三维定位误差上平均降低了90%。
英文摘要：
In signals of opportunity (SOPs)-based positioning utilizing low Earth orbit (LEO) satellites, ephemeris data derived from two-line element files can introduce increasing error over time. To handle the erroneous measurement, an additional base receiver with a known position is often used to compensate for the effect of ephemeris error when positioning the user terminal (UT). However, this approach is insufficient for the long baseline (the distance between the base receiver and UT) as it fails to adequately correct Doppler shift measurement errors caused by ephemeris inaccuracies, resulting in degraded positioning performance. Moreover, the lack of clock synchronization between the base receiver and UT exacerbates erroneous Doppler shift measurements. To address these challenges, we put forth a robust double-difference Doppler shift-based positioning framework, coined 3DPose, to handle the clock synchronization issue between the base receiver and UT, and positioning degradation due to the long baseline. The proposed 3DPose framework leverages double-difference Doppler shift measurements to eliminate the clock synchronization issue and incorporates a novel ephemeris error correction algorithm to enhance UT positioning accuracy in case of the long baseline. The algorithm specifically characterizes and corrects the Doppler shift measurement errors arising from erroneous ephemeris data, focusing on satellite position errors in the tangential direction. To validate the effectiveness of the proposed framework, we conduct comparative analyses across three different scenarios, contrasting its performance with the existing differential Doppler positioning method. The results demonstrate that the proposed 3DPose framework achieves an average reduction of 90% in 3-dimensional positioning errors compared to the existing differential Doppler approach.
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