Characteristics of GNSS Diffracted Signals Near Building Edges and Their Impact on Positioning

An Fujino, Daiki Niimi, Taro Suzuki, Junichi Meguro

Peer Reviewed

Abstract:	In urban environments, Global Navigation Satellite System (GNSS) positioning is severely affected by signal blockage caused by high-rise buildings, resulting in LOS of line-of-sight (LOS) signals and dominance of reflected and diffracted non-line-of-sight (NLOS) signals. NLOS signals include additional propagation delays, which lead to pseudorange errors on the order of several to tens of meters and, therefore, have traditionally been treated as signals to be excluded. However, in dense urban areas, excessive exclusion of NLOS signals often results in an insufficient number of available satellites, significantly degrading the availability of positioning. In this study, instead of rejecting NLOS signals, we focus on diffracted signals generated at building edges and investigate the characteristics of their pseudorange errors based on measurement data, with the aim of utilizing them for positioning. LOS/NLOS classification is performed using GNSS observation data combined with fisheye camera images. By focusing on LOS/NLOS transitions that occur when satellite trajectories cross building edges, diffracted signal observations are extracted. For the diffracted signals extracted, time-series analyzes of signal strength and double-differenced pseudorange residuals are conducted, and cases exhibiting stable residual behavior distinct from reflected signals are identified. Finally, single-point positioning performance is evaluated under three conditions: (1) using all available satellites, (2) using LOS satellites only, and (3) using LOS satellites combined with diffracted signals. When all satellites are used, positioning errors remain on the order of several tens of meters due to reflected signals. Using only LOS satellites produces smaller errors when solutions are available, but solution instability occurs because of limited satellite availability. In contrast, incorporating diffracted signals improves positioning availability without significantly degrading accuracy. This study demonstrates that certain NLOS components, specifically diffracted signals, can be utilized effectively for GNSS positioning in urban environments, suggesting that their selective use is promising for applications requiring continuous positioning availability.
Published in:	Proceedings of the ION 2026 Pacific PNT Meeting April 13 - 16, 2026 Hilton Waikiki Beach Honolulu, Hawaii
Pages:	129 - 139
Cite this article:	Fujino, An, Niimi, Daiki, Suzuki, Taro, Meguro, Junichi, "Characteristics of GNSS Diffracted Signals Near Building Edges and Their Impact on Positioning," Proceedings of the ION 2026 Pacific PNT Meeting, Honolulu, Hawaii, April 2026, pp. 129-139. https://doi.org/10.33012/2026.20591
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