An Improved Opportunistic Localization Algorithm Using LEO Signals Based on PSODC

Positioning based on LEO opportunistic signals can serve as a supplement for the global satellite navigation system, especially in areas where the global satellite navigation signal is denied. The previous positioning method based on LEO opportunistic signals has shown that it is difficult to obtain an accurate initial solution in environments without positioning reference information, which leads to large positioning errors and even failure to converge to the correct solution. To address this issue, a comprehensive particle swarm optimization Doppler shift correction (PSODC) algorithm is proposed in this article to obtain an initial coarse solution. Based on this initial coarse solution, the obtained satellite orbit spatiotemporal information is corrected to reduce the errors caused by satellite orbit spatiotemporal discrepancies. Both simulation and experiment results show the effectiveness of the PSODC method compared with the existing methods. The horizontal positioning accuracy is improved by more than 30% with the assistance of an altimeter. The novel positioning method proposed in this article is of great significance for obtaining the initial solution of Iridium NEXT satellites and improving the positioning accuracy of opportunistic signals.