Abstract
The global navigation satellite system (GNSS) is widely used in smartphone positioning, but its performance can be degraded in urban environments because of signal reflections or blockages. To address these GNSS outages, pedestrian dead reckoning (PDR) is commonly used due to its significant improvements in both the stability and continuity of positioning, which are dependent on three key factors: continuous absolute position, heading and step information. Signals of opportunity are commonly used in positioning, whereas the installation of Bluetooth low energy (BLE) sensors on lampposts can provide an opportunity for positioning and heading estimation in urban canyons. In this article, a system integrating the GNSS, PDR, and BLE techniques is implemented in smartphones to provide a real-time positioning solution for pedestrians, which includes a new position correction method based on BLE heading, a reliable heading estimation integrating BLE and inertial sensors, an unconstrained step detection method with high accuracy, and an extended Kalman filter (EKF) to integrate multiple sensors and techniques. In several field experiments, with improvements in availability and robustness, the heading accuracy of the proposed fusion approach could reach approximately 3 degrees; the positioning accuracy achieved between 2.7 m and 4.2 m, compared with a 30 m error from the GNSS alone. Simultaneously, this system could achieve a high positioning accuracy of 2.4 m with unconstrained smartphones in a mixed environment. The proposed system has been demonstrated to perform well in urban canyons.
Highlights
In recent years, location-based service (LBS) has been an essential part of daily life, whether for mobile mapping, pedestrian navigation, intelligent travel, or emergency caller location [1]–[4]
In real-time mode, the positioning results are shown on the smartphones as shown in Fig. 15(d), with the ground truth supplemented after the experiment for comparison
To evaluate the performance of different technologies in the system, three modes were analyzed during postprocessing, including global navigation satellite system (GNSS)-only, GNSS and pedestrian dead reckoning (PDR) integration, and the integration of GNSS, PDR, and Bluetooth low energy (BLE) position correction, and the results are shown in Fig. 15(a), (b), and (c), respectively
Summary
Location-based service (LBS) has been an essential part of daily life, whether for mobile mapping, pedestrian navigation, intelligent travel, or emergency caller location [1]–[4]. The global navigation satellite system (GNSS) is the most commonly used technology in smartphones, providing up to meter-level. This positioning accuracy can be degraded up to tens or hundreds of meters in deep urban canyons due to signal reflection and blockage [5]. To improve the positioning accuracy in urban areas, several methods for improving GNSS performance or integrating the GNSS with other technologies have been proposed, including multipath mitigation, map-aided methods, vision-based methods, signals of opportunity, and pedestrian dead reckoning (PDR) [6]–[17]. The accuracy of the radio access network (RAN) is inadequate for high-precision positioning.
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