Intrinsic Identification and Mitigation of Multipath for Enhanced GNSS Positioning

Abstract

In global navigation satellite system (GNSS)-based positioning and applications, multipath is by far the most obstinate impact. To overcome paradoxical issues faced by current processing approaches for multipath, this paper employs an intrinsic method to identify and mitigate multipath based on empirical mode decomposition (EMD) and Hilbert–Huang transform (HHT). Frequency spectrum and power spectrum are comprehensively employed to identify and extract multipath from complex data series composed by combined GNSS observations. To systematically inspect the multipath from both code range and carrier phase, typical kinds of combinations of the GNSS observations including the code minus phase (CMP), differential correction (DC), and double differential (DD) carrier phase are selected for the suggested intrinsic approach to recognize and mitigate multipath under typical positioning modes. Compared with other current processing algorithms, the proposed methodology can deal with multipath under normal positioning modes without recourse to the conditions that satellite orbits are accurately repeated and surrounding environments of observing sites remain intact. The method can adaptively extract and eliminate multipath from solely the GNSS observations using intrinsic decomposition mechanism. From theoretical discussions and validating tests, it is found that both code and carrier phase multipath can be identified and distinguished from ionospheric delay and other impacts using the EMD based techniques. The resultant positioning accuracy is therefore improved to an obvious extent after the removal of the multipath. Overall, the proposed method can form an extensive and sound technical frame to enhance localization accuracy under typical GNSS positioning modes and harsh multipath environments.

High-Accuracy Attitude Determination Using Single-Difference Observables Based on Multi-Antenna GNSS Receiver with a Common Clock

“…However, due to the existence of multipath, the STDs of pitch angles in Table 3 are not two-fold less than that of DD-Fix. As shown in Figure 7, after extracting and eliminating the multipath in attitude solution by empirical mode decomposition (EMD) [28], the dispersion of SD-Fix is as expected smaller than that of DD-Fix. Combining with the STDs in Table 4, the STDs of pitch angles for SD-Fix can reach 0.2 • , which is twice less than DD-Fix, and consistent with previous research [6].…”

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“…In 2012, Hirrle et al applied HHT to the synthetic signal noise ratio time series [22]. In 2021, Li et al [23] employed an intrinsic method to identify and mitigate multipath based on EMD and HHT, but C/N 0 was not taken into account.…”

A Multi-Scale Anti-Multipath Algorithm for GNSS-RTK Monitoring Application

“…In recent years, the main methods used to mitigate multipath error in GNSS data have been the selection of monitoring station locations, receiver hardware improvements, and software post-processing [3]. Among these methods, software post-processing has been studied extensively by many researchers.…”