WiFi辅助的基于坐标搜索格网的卫星定位

WiFi Assisted GNSS Positioning Based on Coordinate-Searching Grid

针对城市复杂环境下卫星观测数不足情况下的定位问题,并结合"智慧城市"发展过程中无线信号资源日益丰富这一背景,本文提出了典型泛在无线WiFi信号辅助下的卫星定位方法。该方法首先通过WiFi定位获得概略二维位置信息,在此基础上附加先验高程,然后建立坐标搜索格网,应用最小距离误差算法来获得最后的定位结果。仿真实验结果表明,与WiFi定位得到的初始概略坐标相比,基于格网搜索的卫星定位精度有了明显提高,并且可以避免由于卫星分布过于集中而产生的观测方程系数矩阵的病态问题;另外,先验高程误差也会对最后定位结果产生影响,总体趋势是高程误差越大,定位精度越低,但是合理范围内的高程偏差(例如10m以内)仍然可以满足普通导航定位的需求。

A kind of new method called WiFi assisted GNSS positioning using minimum range error algorithm is proposed in this paper to solve positioning problem when the satellites in view is not sufficient in urban canyon while wireless signal resources are increasingly rich in the development of smart city.The proposed method firstly obtains the coarse two-dimensional position information through WiFi positioning.Secondly,a coordinate-searching grid is established,and the minimum distance error algorithm is used to get the final position with the help of adding priori geodetic height data.An experiment is carried out and the results show that the satellite positioning accuracy by grid-searching is significantly improved compared with that of the initial coordinates obtained from WiFi positioning,and the ill-conditioned coefficient matrix problem could be avoided as there is no need to solve observation equation.In addition,bias in priori geodetic height would also have an impact on the final positioning accuracy,and the overall trend is that,the greater the deviation is,the lower the positioning precision is.What’s more,the magnitude of which within specific range(for instance,less than 10 m)could still meet the need of ordinary positioning and navigation.