自动推算室内接入点坐标算法

随着基于位置服务的应用与发展，室外和室内定位技术都得到了飞速发展。特别是在WiFi定位技术的不断完善下，室内定位技术有了广泛的应用，但是，WiFi定位技术的两种定位方式均需预先知道室内网络接入点的精确坐标，这一要求无法满足一些紧急情况下的定位需求。因此，本文提出了一种基于M估计的自动推算室内接入点坐标算法。该算法借助在室内外交界处同时获取卫星定位信息和WiFi信号的RSSI信息，巧用分段RSSI测距算法提高长距离RSSI测距精度，结合残差绝对和最小的M估计改进距离交会定位算法，最终推算出室内接入点的三维坐标，实现自动化推算过程。试验结果表明：该方法的定位精度比常规距离交会最小二乘算法提高了50%，能够快速实时较精确地推算室内接入点的坐标，进一步完善了WiFi定位技术。

An Algorithm for Automatically Calculating the Coordinate of Indoor Access Points

With the application and development of location-based service, outdoor and indoor positioning technology has been developing rapidly.Indoor positioning technology has been widely utilized especially in the continuous improvement of WiFi positioning technology.But two positioning methods of WiFi positioning technology are required to know the exact coordinates of the indoor network access points. This requirement cannot meet some emergency location requirements. Therefore, this paper presents an algorithm for automatically calculating the coordinate of indoor access points based on M estimation. The algorithm utilizes the satellite location information and the RSSI value of WiFi signal at the junction of indoor and outdoor, uses the segmented RSSI ranging algorithm to improve the accuracy of long distance RSSI distance and combines the residual absolute and minimum M estimation to improve distance intersection positioning algorithm. Finally the three-dimensional coordinates of the indoor access points were calculated, to achieve automated projection process.The experiment results show that the positioning accuracy of this method is 50％ higher than conventional distance intersection least squares algorithm and the coordinates of the indoor access points can be calculated more accurately in real time,and the WiFi positioning technology is further improved.