A Comparison Research of Navigation and Positioning Methods for Low Earth Orbit Communication Constellations

‍ ‍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.