Performance evaluation of GPS and BeiDou hybrid positioning using a low cost GNSS receiver in Nigeria

Abstract

This study evaluates the performance of Global Positioning System (GPS)-only, BeiDou-only, and hybridized GPS+BeiDou Global Navigation Satellite System (GNSS) constellations in Nigeria, with emphasis on positional stability and the benefits of multi-constellation integration. A dual-frequency u-blox ZED-F9P GNSS receiver was deployed at a static reference station at the Department of Pure and Applied Physics, Ladoke Akintola University of Technology, Ogbomoso, Nigeria. Continuous 24-hour GNSS observation data were collected at 4 Hz over a 14-day period in May 2025. The raw data were converted to Receiver Independent Exchange (RINEX) Format using the Real-Time Kinematic Library (RTKLIB) suite and processed with RTKPOST to obtain positioning solutions. The data were analyzed in terms of carrier-to-noise density ratio (C/N₀), number of satellites visible (NSV), satellite elevation angle, positional stability, and Single Point Positioning (SPP) performance. The results showed that GPS provided more stable satellite visibility, with visible satellites ranging from 6 to 11 per epoch and a daily average NSV of 8.22 ± 0.05, while BeiDou ranged from 4 to 8 visible satellites per epoch, with a daily average NSV of 6.05 ± 0.11. GPS maintained 31 visible Pseudo-Random Noise (PRN) satellites throughout the observation period, whereas BeiDou varied between 28 and 31 PRNs. The C/N₀ analysis showed that GPS L1 provided the strongest signal quality, with values ranging from 36.26 dB-Hz to 39.05 dB-Hz and a mean value of 38.10 ± 0.55 dB-Hz. In terms of positional stability, GPS recorded lower standard deviations in latitude, longitude, and altitude, ranging from 1.15 m to 1.75 m, 1.38 m to 1.94 m, and 4.16 m to 5.69 m, respectively. BeiDou showed higher variability, with corresponding values ranging from 2.07 m to 3.39 m, 2.07 m to 4.12 m, and 6.36 m to 9.85 m. However, BeiDou provided a complementary elevation-angle advantage, with a mean elevation angle of 29.06 ± 2.08°, compared with 25.71 ± 2.39° for GPS. The hybridized GPS+BeiDou solution delivered the best positioning performance, with average Two-Distance Root Mean Square (2DRMS), Circular Error Probable (CEP), Spherical Error Probable (SEP), and Mean Radial Spherical Error (MRSE) values of 3.93 m, 1.64 m, 3.66 m, and 4.83 m, respectively. These values represent an improvement of approximately 14% over GPS-only and about 46–49% over BeiDou-only, depending on the positioning performance metric considered. The findings demonstrate that GPS+BeiDou hybridization improves GNSS positioning performance, reliability, and solution stability over the study area.