Research On Positioning Technology Based On LEO Communication And Navigation Fusion Signal

China has begun building the next-generation Bei Dou system following the completion of Bei Dou-3,with intentions to establish a more extensive,integrated,and intelligent national integrated positioning,navigation,and timing system by 2035.However,the global navigation satellite system still has limitations,such as weak landing signals and susceptibility to interference in complex environments.Due to extensive worldwide coverage,minimal transmission latency,and high survivability,the LEO system has improved the positioning and navigational capabilities of the global navigation satellite system.The LEO system can be built quickly and inexpensively,and it is anticipated to play a significant role in the Bei Dou system’s future development.Being a crucial part of the integrated positioning,navigation,and timing system,communication and navigation fusion has research value.This thesis integrates the navigation signal of Beidou B1 C with the communication signal of the Iridium satellite in light of the pressing need for LEO satellite navigation applications and the scarcity of navigation frequency resources.Based on this,the positioning technology of the LEO communication and navigation fusion signal is studied,and the following work is done:1)The relationship between orbit height,orbital inclination,and satellite coverage is examined,and three different types of LEO constellation models are built in accordance with the characteristics of LEO systems that can enhance the positioning capability of the global navigation satellite system.By comparing the positioning performance of various constellation models,it is proved that the LEO constellation enhancement system combining high and low orbital inclination has superior navigation enhancement effects.Thus,a model for the next-generation Bei Dou LEO constellation is proposed.According to the experimental results,the LEO constellation can offer a greater range of stable,secure,and dependable positioning services in global regions.2)Improvements to the Chan algorithm and the Chan Taylor hybrid weighting algorithm have been developed to solve the problem of positioning error in the TDOA positioning algorithm.Whereas the improved Chan Taylor hybrid weighting algorithm reduces positioning error by incorporating weighting factors,the improved Chan algorithm uses the initial result for rectification to estimate the final result.According to the simulation results,the improved Chan Taylor hybrid weighted algorithm has the smallest positioning error and the best positioning accuracy,followed by the improved Chan algorithm.This is in comparison to the original Chan algorithm and the Taylor algorithm.3)In order to overcome the problems of low precision and sluggish speed in pseudo range single point positioning,a fast adaptive weighted least squares algorithm is developed.The weighted least squares algorithm and the direct calculation algorithm are combined to improve.The adaptive weighting matrix is created based on the pseudo range of the actual position of the satellite and receiver,as well as the linearized pseudo range deviation.The simulation results demonstrate that the fast adaptive weighted least squares algorithm increases positioning accuracy when compared to the direct calculation algorithm while decreasing computational complexity when compared to the adaptive weighted least squares algorithm.