ARABIS: an Asynchronous Acoustic Indoor Positioning System for Mobile Devices

Abstract

Acoustic ranging based indoor positioning solutions have the advantage of higher ranging accuracy and better compatibility with commercial-off-the-self consumer devices. However, similar to other time-domain based approaches using Time-of-Arrival (ToA) and Time-Difference-of-Arrival (TDoA), they suffer from performance degradation in the presence of multi-path propagation and low received signal-to-noise ratio (SNR) in indoor environments. In this thesis, we present ARABIS, a robust and low-cost acoustic indoor positioning system (IPS) for mobile devices using an asynchronous TDoA-based solution. We develop a low-cost acoustic board custom-designed to support large operational ranges and extensibility. To mitigate the effects of low SNR and multi-path propagation, we devise robust algorithms that iteratively remove possible outliers by taking advantage of redundant TDoA estimates. Experiments have been carried out in two testbeds of sizes 10.67m × 7.76m and 15m × 15m, one in an academic building and one in a convention center. The proposed system achieves average and 95% quantile localization errors of 7.4cm and 16.0cm in the first testbed with 8 anchor nodes and average and 95% quantile localization errors of 20.4cm and 40.0cm in the second testbed with 4 anchor nodes only.