Real-time GNSS NLOS detection and correction aided by Sky-pointing camera and 3D LiDAR

Xiwei Bai, Weisong Wen, Guohao Zhang, Li Ta Hsu

Research output: Chapter in book / Conference proceedingConference article published in proceeding or bookAcademic researchpeer-review

5 Citations (Scopus)


Robust and globally referenced positioning is the basis of fully autonomous driving in diverse scenarios. Globally navigation satellite system (GNSS) is currently the main source providing globally referenced positioning. Satisfactory accuracy (5~10 meters) can be obtained in sparse areas. However, the GNSS positioning error can go up to even 100 meters in dense urban areas due to the multipath effects and none-line-of-sight (NLOS) reception caused by reflection and blockage from buildings. NLOS is currently the dominant component degrading the performance of GNSS positioning. Recently, the camera is employed to detect the NLOS satellites and then the NLOS are excluded from GNSS calculation. This exclusion can cause severe distortion of satellite distribution, due to the excessive NLOS receptions in deep urban canyon. This paper proposes to correct the NLOS receptions with the aid of 3D LiDAR ranging after detecting NLOS receptions using camera. The sky-pointing monocular camera is firstly employed to detect satellite visibility. Then, the NLOS delay is modeled using the satellite elevation angle, azimuth angle and distance from receiver to possible reflector which is ranged by 3D LiDAR. The pseudorange measurements are corrected using the estimated NLOS delay. Finally, the GNSS positioning is improved using corrected pseudorange measurements and healthy (visible) satellites. The proposed method is verified through real road tests in a deep urbanized canyon of Hong Kong. The result shows that the proposed method can effectively improve the GNSS positioning performance by decreasing the mean error from 22.01 to 14.96 meters.

Original languageEnglish
Title of host publicationION 2019 Pacific PNT Meeting Proceedings
PublisherThe Institute of Navigation
Number of pages13
ISBN (Electronic)0936406224, 9780936406220
Publication statusPublished - Apr 2019
EventInstitute of Navigation 2019 Pacific Positioning, Navigation and Timing Meeting, PACIFIC PNT 2019 - Honolulu, United States
Duration: 8 Apr 201911 Apr 2019

Publication series

NameProceedings of the Institute of Navigation Pacific Positioning, Navigation and Timing Meeting, Pacific PNT
ISSN (Print)2331-6284


ConferenceInstitute of Navigation 2019 Pacific Positioning, Navigation and Timing Meeting, PACIFIC PNT 2019
Country/TerritoryUnited States

ASJC Scopus subject areas

  • Transportation
  • Ocean Engineering
  • Aerospace Engineering
  • Electrical and Electronic Engineering
  • Computer Science Applications

Cite this