Dianxin kexue (Apr 2024)
Bidirectional measurement differential positioning method for LEO communication satellites
Abstract
In non-terrestrial network, leveraging resources such as satellite-to-earth links, satellite payloads, and ground terminals of low earth orbit (LEO) communication satellites to achieve positioning calculations is one of the important technical means for realizing the integration of sensing and communication in future 6G network. In scenarios such as direct-to-handset satellite, terminal designs were often configured to communicate with only one satellite, making the exploration of single-satellite positioning methods of urgent significance. Addressing the challenges of poor positioning accuracy, difficulty in clock synchronization, and slow convergence speed associated with previous single-satellite continuous observation, a bidirectional measurement differential positioning method was proposed in the context of low-orbit constellations. Additionally, a position updating strategy based on the satellite position accuracy factor was designed. Utilizing the satellite-to-earth link, the method employed a one-way bidirectional ranging technique to eliminate clock errors and compensated for the spatial deficiency of single-satellite observation through cumulative time measurement and random terminal switching, thereby optimizing terminal positioning performance. The results show that measurement through random satellite switching, compared to terminals that maintain single-satellite measurement without switching, enhances positioning performance by nearly 100%. By jointly solving multiple observation data over time, the accuracy convergence speed can be increased, and positioning error can be reduced. Within a simulation time of 180 s, using 512 observation data, with a terminal switching frequency of 19 times, the optimal positioning accuracy can reach 299.5 m.
