To improve the locating accuracy for wireless sensor networks (WSN) in the mixed propagation environment of non-line-of-sight (NLOS) and line-of-sight (LOS) during passive localization

an algorithm named residual test based on arc-edged convex hull (RTAC) is proposed. RTAC algorithm uses the distribution characteristics of ranging residuals of sensors to construct an offset circle model reflecting the distribution of residual points in the polar coordinate system

and uses the minimal arc-edged convex hull to group and identify the sensors in order to realize the LOS sensor identification in the network. The simulation results demonstrate that RTAC algorithm can realize the correct identification of LOS sensors under a lower computational complexity

and can obtain better location performance. RTAC algorithm is an efficient algorithm for LOS sensor identification in mixed propagation environment.