WiFi辅助下附有高程先验信息的GNSS定位

WiFi Assisted GNSS Positioning with Priori Geodetic Height

WiFi(wireless fidelity)辅助下附有高程信息的GPS定位可以解决城市环境下卫星数不足时的定位问题,该方法首先利用WiFi定位获得概略二维坐标,然后通过附有高程先验信息的GPS定位来求解最后的位置参数。在此基础上作了进一步的研究和探讨,将卫星数不足情况下的单GPS定位问题延伸到多系统(BDS+GPS)定位,并探讨了卫星天空几何分布和先验高程精度对最终定位结果的影响。实验结果表明:当卫星分布不均匀或过于集中时,观测方程系数矩阵趋于病态,使得定位结果误差变大,多系统(BDS+GPS)定位可以削弱卫星分布对于定位结果的影响;另外,当先验高程偏差增加时,最后的定位精度也会随之下降,但合理范围内的偏差仍然可以满足普通导航定位的需求。

WiFi assisted GPS positioning with fixed geodetic height could be used to solve positioning problems in the situation where there are not enough GPS satellites in view. This method includes two steps: firstly, approximate longitude and latitude are obtained through WiFi positioning method, and then final coordinates is worked out by combing three GPS observations and fixed geodetic height. This paper extends the study from using GPS to using BDS due to insufficient satellites. Also, the influence of satellite geometric distribution and priori geodetic height bias on positioning accuracy is discussed. An experiment is carried out and results showed that, observation equation coefficient matrix tends to be ill-conditioned and the positioning accuracy would be greatly decreased if satellites observed in view are too closed to each other. But the influence mentioned above could be weakened by using observations from different navigation satellite systems, such as BDS+GPS. In addition, the final positioning accuracy will decrease as the priori height bias increases, but bias within a reasonable range can still meet the needs of ordinary navigation and positioning.