Characterisation and Mitigation of Multipath Effects on Satellite Positioning Accuracy: A Case Study of Ladoke Akintola University of Technology, (LAUTECH), Ogbomoso, Nigeria
Oluwadara Abosede Oyelowo
Department of Science Laboratory Technology, Federal Polytechnic Ayede, Ayede, Oyo State, Nigeria.
Adebayo S. Adewumi
Department of Pure and Applied Physics, Ladoke Akintola University of Technology, Ogbomoso, Oyo State, Nigeria.
George A. Àlàgbé *
Department of Pure and Applied Physics, Ladoke Akintola University of Technology, Ogbomoso, Oyo State, Nigeria.
Efua A. Ogobor
Physical and Life Science Division, National Space Research and Development Agency, Abuja, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
The Global Navigation Satellite System (GNSS) was developed to offer precise, accurate, and reliable positioning for various scientific and real-time applications, including everyday communication, navigation, disaster management, and security. Despite the increasing demand to enhance GNSS accuracy in urban canyons, such as on campuses, previous research has rarely tackled the challenge of mitigating multipath effects using raw observation dual-frequency data logs from a compact, low-cost GNSS receiver, especially on Nigerian campuses. A u-blox ZED-F9P GNSS receiver was used to log data continuously for thirty days in dual-frequency GPS-only, GLONASS-only, and GPS+GLONASS hybrid modes at a 4Hz sampling rate across fifteen reference coordinates (RCs) at Ladoke Akintola University of Technology, Ogbomoso, Nigeria. In this study, performance metrics such as carrier-to-noise ratio (C/No), Precise Point Positioning (PPP), Two-Distance Root Mean Square (2DRMS), Circle of Error Probable (CEP), Spherical Error Probable (SEP), Mean Radial Spherical Error (MRSE), Standard Deviation Error (S.D), Number of Satellites Visible (NSV), and Dilution of Precision (DOP) were used to evaluate the position accuracy of the processed data. The results showed that LAUTECH Hall and Chapel RC revealed less than 0.006m horizontal and 0.029m vertical accuracy in PPP when operating in GPS+GLONASS hybrid mode, indicating the best position accuracy for GNSS PPP among the RCs. Further analysis indicates that the LAUTECH Hall, Mosque, and Chapel RC have a mean C/No higher than 40 dB Hz, a maximum NSV of 10, and a low GDOP of 2.5, PDOP of 2.2, HDOP of 1.0, and VDOP of 1.9. It was noticed that the GPS+GLONASS hybrid mode adopted in this study mitigates multipath effects with specific positioning accuracy of less than 0.005m at about three RCs in LAUTECH.
Keywords: Multipath effects, positioning accuracy, GNSS, obstruction, mitigation.