Indoor fast positioning algorithm based on 5G Advanced carrier phase

The rapid advancement of industrial intelligence has led to a surge in demand for high-precision, real-time positioning systems. While Global Navigation Satellite Systems (GNSS) have achieved significant success in outdoor environments, indoor positioning still lacks accurate and reliable technologies. This study introduces a hybrid 5G Advanced positioning method that integrates Round-Trip Time (RTT) and carrier-phase observations. Key innovations include a multi-frequency ambiguity resolution model utilizing “extra-wide-lane (EWL)/sub-extra-wide-lane (SEWL)” signals, a sliding-window dynamic adjustment algorithm for robust ambiguity resolution, and double-difference geometric constraints for terminal positioning. Simulations reveal that RTT ranging precision greatly affects initial positioning errors and convergence speed. With low RTT accuracy ($\sigma_{P}=3 \mathrm{~m}$), the RMSE reaches 0.311 m, taking about 150 s to converge. With high RTT accuracy ($\sigma_{P}=0.3 \mathrm{~m}$), the RMSE achieves 0.064 m, and the system can converge within 30 s. Carrier-phase ranging accuracy mainly impacts post-convergence stability. Low accuracy ($\sigma_{\phi}=0.2$ cycles) causes $\pm 0.1 \mathrm{~m}$ oscillations, while high accuracy ($\sigma_{\phi}=0.01$ cycles) keeps residuals within $\pm 0.01 \mathrm{~m}$.