BDS-3/GPS在遮挡环境下定位性能分析

针对在全球卫星导航系统(GNSS)信号易遮挡地区，单一系统可见卫星数较少，定位性能不理想甚至难以满足定位需求的问题，分析北斗三号(BDS-3)在不同区域遮挡环境下对定位性能的改善. 通过全球不同区域MGEX(Multi-GNSS Experiment)监测站的观测数据，采用GPS、BDS-3、BDS-3/GPS组合定位三种模式，在不同模拟遮挡环境下进行伪距单点定位，分析了各模式下可见卫星颗数、历元利用率、几何精度衰减因子(GDOP)值和定位精度. 结果表明:在北半球区域，相较于其他方向遮挡，GPS模式在低纬度地区南面遮挡的定位稳定性和精度最高，在中高纬度地区北面遮挡的定位稳定性和精度最高，BDS-3和BDS-3/GPS组合模式在低纬度地区各方向遮挡定位精度相当，在中纬度和中高纬度地区，北面遮挡的精度明显优于其他方向遮挡的定位精度. BDS-3/GPS组合定位模式，大大增加了可见卫星颗数，历元利用率提高，卫星空间几何结构改善，GDOP值降低，稳定性和定位精度明显优于单系统. 

Analysis of positioning performance of BDS-3/GPS in shadow environment

In areas where GNSS signals are easily sheltered, the number of visible satellites in a single navigation system is small, and the positioning performance is not ideal or even difficult to meet the requrements of positioning needs. In this paper, the improvement of BDS-3's positioning performance in shadow environments is analyzed in different area. Based on the observation data of MGEX monitoring stations in different regions of the world, three modes of GPS, BDS-3, and BDS-3/GPS combined positioning are used to perform pseudo-range single-point positioning under different simulated shadow environments, and the number of visible satellites in each mode is analyzed, together with epoch utilization, GDOP value and positioning accuracy. The results show that in the northern hemisphere, compared to shadow in other direction, the GPS mode has the highest positioning stability and accuracy in the south of low latitudes, and the highest positioning stability and accuracy in the north of the middle and high latitudes. BDS-3 and BDS-3/GPS mode has the same positioning accuracy in all directions in low latitude areas. In mid-latitude and mid-high latitude areas, the accuracy of north shadowed is significantly better when shadow is in the north direction than that of other directions. The BDS-3/GPS combined positioning mode greatly increases the number of available satellites, improves the epoch utilization rate, improves the satellite spatial geometry, and reduces the GDOP value, which is significantly better than a single system in stability and positioning accuracy.