Positioning Performance Evaluation of BDS/QZSS and Its Combined Systems in China, Japan and Their Peripheral Areas

The positioning performance of BeiDou Navigation Satellite System (BDS)/Quasi-Zenith Satellite System (QZSS) and its combined systems in China, Japan and their peripheral areas is evaluated and analyzed by using the observation data of the multi-GNSS experiment (MGEX) from the number of visible satellites, dilution of precision, the multipath effect, the signal-to-noise ratio (SNR), the static precise point positioning (PPP) and kinematic PPP. The results show that the combination of QZSS and BDS system can increase the number of satellites and provide better spatial geometry distribution, thus ensuring the accuracy, reliability and availability of positioning. Because the constellation structure of QZSS satellite is similar to that of BDS satellite, its multipath effect is consistent with that of BDS satellite. The SNR of MEO(medium earth orbit) satellite is 2-3 dBHz higher than that of inclined geosynchronous orbit(IGSO) satellite at the same altitude angle. For static and kinematic PPP, the improvement of BDS+QZSS combination is more obvious than that of BDS single system at low altitude angle when the altitude angle is larger (40°). The improvement rate of E, N and U directions static PPP can reach more than 20%, where kinematic PPP can reach more than 30%. QZSS plays a complementary and enhanced role in BDS positioning in Japan, China and surrounding areas. In the complex environment (such as city, building intensive area, mountain area, et al.) where the signal is easy to block, it will have better application value.