Robust Indoor Positioning with Smartphone by Utilizing Encoded Chirp Acoustic Signal

Area of Science:

• Navigation and Positioning
• Acoustic Signal Processing
• Indoor Localization Technologies

Background:

• Indoor positioning is a critical research area for navigation.
• Acoustic signal-based positioning offers high accuracy, low cost, and smartphone compatibility.
• Existing methods face challenges with accuracy and robustness in complex indoor environments.

Purpose of the Study:

• To propose a novel acoustic positioning method called RATBILS (Acoustic Positioning System).
• To enhance indoor localization accuracy and robustness using encoded chirp acoustic signals.
• To evaluate the performance of RATBILS against traditional methods.

Main Methods:

• Utilizing encoded chirp acoustic signals transmitted by base stations.
• Implementing a three-step process on smartphones: preprocessing, Time of Arrival (TOA) estimation, and Time Difference of Arrival (TDOA) calculation.
• Employing band-pass filters for noise reduction and signal decoding for source locking.
• Utilizing coarse and fine detection for robust TOA estimation, emphasizing first arrival and mitigating multipath/non-line-of-sight (NLOS) effects.

Main Results:

• RATBILS achieved a positioning error of 0.23 m at 92% in scene 1, region 1, outperforming traditional methods.
• A positioning error of 0.56 m at 92% was achieved in scene 1, region 2, also superior to traditional methods.
• In scene 2, the maximum average positioning error was 1.26 m, significantly better than 3.33 m and 3.87 m from traditional methods.

Conclusions:

• The proposed RATBILS system demonstrates superior performance in indoor acoustic positioning.
• The method provides accurate and robust localization, even in challenging NLOS conditions.
• RATBILS represents a significant advancement for smartphone-based indoor navigation systems.