中文摘要：

定位技术是无线传感器网络重要的共性支撑技术之一。在近似三角形内点测试APIT算法基础上提出了基于中垂线分割的改进算法PB-APIT。利用三条边的中垂线将APIT算法中的三角形分割为4个或6个可用小区域，并以检测信号的强弱进一步来判定未知节点的位置，即判断未知节点处于哪一个可用小区域，从而减小原APIT算法的定位区域，提高定位精度。仿真结果表明，与原APIT算法相比，所改进的算法精度上有较大提高。

英文摘要：

APIT is a canonical range-free localization algorithm for wireless sensor networks. Although it can make a well localization performance, it ignores some features that can be used to further reduce the error of localization. In order to improve the localization accuracy, a novel algorithm is proposed to reach a better performance. To localize an unknown node, the neighbor anchors establish triangles and estimate the topology relationships between the unknown node and these triangles. When a triangle contains the unknown node, it utilizes the perpendicular bisector of each side to divide itself into 4 or 6 sub-areas for further judgment. And, the position of the unknown node is set as the center of mass with overlapped small sub-areas. Simulation experiments prove that PB-APIT algorithm can remarkably improve localization accuracy compared to APIT algorithm, especially in the large scale wireless sensor network.