A Geometrical Approach to Multipath Localization and Mitigation for Static Undifferenced GPS Data

Abstract

Multipath is a limiting factor for accurate positioning by global navigation satellite system (GNSS). Different hardware and computational techniques have been proposed for its mitigation. Here a geometrical approach for multipath localization and mitigation is presented: localization is performed by ray-tracing and mitigation by analyzing the residuals of ambiguity resolved precise point positioning. The main advantages of the method are its ability to correct nearly the multipath-affected parts of raw data and its relative independence of observation duration (e.g., more than 1 h). The method is based on a ray-tracing algorithm and is applicable to all GNSS constellations. It is independent of physical properties of reflecting surfaces, receiver/antenna type and observation sampling rate. The methodology was implemented on static real global positioning system (GPS) data acquired during six consecutive days in presence and in absence of a metallic reflecting plate. The analysis was performed on two kinds of data series: observations residuals and epoch-wise coordinates. The overall RMSs of observations residuals were reduced by 55% on average. The RMS of easting, northing, and elevation residual time series resulting from affected observations were 8.1 mm, 13.3 mm, and 23.8 mm, respectively; while they were reduced to 6.9 mm, 9.7 mm, and 22.4 mm after correction (22% improvement in horizontal and a minor improvement in vertical components).