NLOS GPS signal detection using a dual-polarisation antenna

• Published in: GPS solutions Vol. 18; no. 1; pp. 15 - 26
• Main Authors: Jiang, Ziyi, Groves, Paul D.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.01.2014; Springer Nature B.V
• Subjects: Antennas; Atmospheric Sciences; Automotive Engineering; Carrier density; Earth and Environmental Science; Earth Sciences; Electrical Engineering; Geophysics/Geodesy; Global positioning systems; GPS; Interference; Lower bounds; Original Article; Polarization; Position errors; Signal detection; Signal quality; Signal reception; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Urban areas; Urban environments; Multipath; GPS; Dual-polarisation antenna; Non-line-of-sight; NLOS
• ISSN: 1080-5370; 1521-1886
• DOI: 10.1007/s10291-012-0305-5

The reception of indirect signals, either in the form of non-line-of-sight (NLOS) reception or multipath interference, is a major cause of GNSS position errors in urban environments. We explore the potential of using dual-polarisation antenna technology for detecting and mitigating the reception of NLOS signals and severe multipath interference. The new technique computes the value of the carrier-power-to-noise-density ( C / N 0 ) measurements from left-hand circular polarised outputs subtracted from the right-hand circular polarised C / N 0 counterpart. If this quality is negative, NLOS signal reception is assumed. If the C / N 0 difference is positive, but falls below a threshold based on its lower bound in an open-sky environment, severe multipath interference is assumed. Results from two experiments are presented. Open-field testing was first performed to characterise the antenna behaviour and determine a suitable multipath detection threshold. The techniques were then tested in a dense urban area. Using the new method, two signals in the urban data were identified as NLOS-only reception during the occupation period at one station, while the majority of the remaining signals present were subject to a mixture of NLOS reception and severe multipath interference. The point positioning results were dramatically improved by excluding the detected NLOS measurements. The new technique is suited to a wide range of static ground applications based on our results.