GPS Solutions

, 23:79 | Cite as

Performance analysis of indoor pseudolite positioning based on the unscented Kalman filter

  • Xin Li
  • Peng ZhangEmail author
  • Guanwen Huang
  • Qin Zhang
  • Jiming Guo
  • Yinzhi Zhao
  • Qingzhi Zhao
Original Article


The indoor pseudolite (PL) code-based solution is not sufficiently precise, and conducting prolonged static carrier phase observations is impractical due to the static PL geometric distribution. Thus, a high-precision indoor PL positioning, which is generally based on the known point initialization (KPI) method and adopts the extended Kalman filter (EKF), is used to obtain the PL float ambiguity solution. However, the first-order linear truncation error of the EKF cannot be neglected because the indoor space is small, and its performance is quite dependent on the accuracy of the initial coordinates in the KPI. In this study, a well-suited nonlinear parameter estimation method, which is expected to have high precision and low dependence on the initial coordinate values, namely the unscented Kalman filter (UKF), is introduced and applied in PL positioning. Based on the relative positioning model and the KPI method, the positioning performance of the EKF and UKF under code-based differential pseudolite (DPL) positioning and phase-based real-time kinematic (RTK) positioning modes is compared and analyzed. Numerical results indicate that the computational efficiencies of the EKF and UKF are of the same level, though the former is slightly superior to the latter. In terms of the DPL positioning results, the precision of the UKF is higher with a decimeter-level improvement compared with that of the EKF. The dependence on the accuracy of the initial coordinates of UKF is reduced to some extent, which makes it a convenient technique, especially in the PL ambiguity resolution of the RTK positioning with fast convergence speed. The UKF outperforms the EKF and is more practicable in indoor PL positioning. The UKF can also achieve a decimeter-level positioning precision in DPL and a centimeter-level positioning precision in RTK.


Indoor pseudolite (PL) Known point initialization (KPI) Unscented Kalman filter (UKF) Differential pseudolite (DPL) positioning Real-time kinematic (RTK) positioning 



Ambiguity resolution


Double differenced


Differential GPS positioning


Differential pseudolite


Extended Kalman filter


Geometric dilution of precision


Global navigation satellite system


Global positioning system


Initial coordinate bias


Known point initialization


Process noise of coordinates




Pseudolite ambiguity resolution


Real-time kinematic positioning


Single differenced


Single point positioning


Standard deviation


Unscented Kalman filter


Universal software radio peripheral



This work was supported by the China Postdoctoral Science Foundation (No. 2018M633441); the Fundamental Research Funds for the Central Universities, Chang’an University, 2018 (No. 300102268102); and the Programs of the National Natural Science Foundation of China (41790445, 41774025, 41604001, and 41731066).


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Xin Li
    • 1
  • Peng Zhang
    • 2
    Email author
  • Guanwen Huang
    • 1
  • Qin Zhang
    • 1
  • Jiming Guo
    • 2
  • Yinzhi Zhao
    • 2
  • Qingzhi Zhao
    • 3
  1. 1.College of Geology Engineering and GeomaticsChang’an UniversityXi’anChina
  2. 2.School of Geodesy and GeomaticsWuhan UniversityWuhanChina
  3. 3.College of GeomaticsXi’an University of Science and TechnologyXi’anChina

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