面向低轨通信星座的导航定位方法比对研究
A Comparison Research of Navigation and Positioning Methods for Low Earth Orbit Communication Constellations
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摘要: 当前基于低轨卫星的导航定位方法研究成为国内外热点,其中基于低轨通信卫星的导航定位技术更是当前研究的重点方向。然而低轨通信星座较低的时空基准精度给导航定位带来了较大的挑战,针对弱时空基准约束的低轨卫星导航定位体制设计还处在研究的初级阶段。本文针对低轨通信星座的导航定位服务需求,基于LEO通信卫星的伪码测距信号与多普勒测频信号,开展精度因子(Dilution of Precision,DOP)及定位精度均方根误差(Root Mean Square Error,RMSE)分析,并对两类测量体制下的低轨通信星座导航定位服务性能进行分析论证。理论分析与仿真结果表明,在设定低轨通信卫星10 m~30 m弱时空基准误差的约束下,多普勒测频体制具有更优的导航定位精度,其周期平滑后的三维RMSE值为1.28 m,相比伪码测距体制下的三维RMSE值优化了86.8%;二维RMSE值为0.99 m,相比于伪码测距体制提升了52.9%。本文提出了一种较为可靠的低轨通信星座多普勒定位方案,为未来低轨通信卫星用于导航定位服务提供了有益参考。Abstract: The research of navigation and positioning methods based on low earth orbiting (LEO) satellites had become a hot spot both at home and abroad, among which the navigation and positioning technology based on communication satellites was the key direction of current research. However, the weak temporal and spatial reference accuracy of LEO communication constellation brought greater challenges to navigation and positioning, and the design of LEO satellite navigation and positioning system for weak temporal and spatial reference accuracy constraints was still in the initial stage of research. Aiming at the navigation and positioning service requirements of LEO communication constellations, based on the pseudo-code ranging signals and Doppler frequency measurement signals of LEO communication satellite, the dilution of precision (DOP) and root mean square error (RMSE) analysis were carried out, and the performance of navigation and positioning services of LEO communication constellation under the two types of measurement systems was analyzed and demonstrated. Theoretical analysis and simulation results showed that under the constraint of the setting weak temporal and spatial reference accuracy of 10 m~30 m for LEO communication satellites, the Doppler frequency measurement system had better navigation and positioning accuracy, and the three-dimensional (3-D) RMSE value after periodic smoothing was 1.28 m, which was 86.8% better than the 3D RMSE value under the pseudo-code ranging system. The two-dimensional (2-D) RMSE value is 0.99 m, which is 52.9% higher than that of the pseudo-code ranging system. Under the two measurements of pseudo-code ranging and Doppler frequency measurement, the DOP value had different manifestations. Based on the setting LEO communication constellation, the Position DOP (PDOP) value obtained under the pseudo-code ranging measurement was 1.21, and the PDOP value obtained under the Doppler frequency measurement was 9.02. Therefore, the DOP value could be used as a criterion for judging the geometric configuration of the satellite within the two systems. Generally, only the DOP value of pseudo-code ranging measurement was used as an indicator of the constellation configuration. This paper proposes a more reliable Doppler positioning scheme for LEO communication constellation, which provides a useful reference for future LEO communication satellites to be used for navigation and positioning services.