Studying the effects of multi-path error on smartphone positioning using GNSS data

AbstractWith the continuous growth of smartphone location-based applications, enhancing the positioning accuracy of these devices has become increasingly critical. Smartphones are primarily used in urban areas, where they often receive Global Navigation Satellite Systems (GNSS) signals amidst considerable noise and face challenges such as signal blockage due to numerous obstructions. Despite this, no comprehensive analysis has been conducted thus far to evaluate the impact of multipath error on the real-time accuracy of smartphone positioning. Therefore, this study aims to examine the influence of multipath error on determining the position of smartphones by utilizing raw GNSS observations. To calculate the multipath effect rate of the GNSS code observations without the need to estimate the phase ambiguity, we employ the Code Minus Carrier Phase (CMCD) observable. This indicator is then utilized to correct code rate measurements. Given that the calculation of multipath rate using CMCD measurements relies on eliminating phase jumps, we employed a Doppler integration algorithm to address this issue. The results of code-only positioning are examined across three modes: GPS-only, multi-GNSS without multipath correction, and multi-GNSS with multipath correction. These results reveal that utilizing multi-system measurements enables the estimation of positions in a greater number of epochs. The entire measurement duration becomes kinematic, and applying multipath correction to the received signal helps reduce RMS errors to approximately 2 meters for the x component (east-west) and about 0.5 meters for the y component (north-south) along the entire path.