In the localization service of two dimensional space

reference nodes optimizing selection theorem in two dimensional space is proposed on the basis of analyzing the location error areas.The theorem of refeence nodes optimizing selection indicates that purposive selection of reference nodes will minimize the location error in the process of indoor localization.Meanwhile this theorem builds up theoretical foundation for the layout and selection of reference nodes in indoor environment.Based on this

reference nodes optimization selection algorithm(RNOS Algorithm)is proposed by improving the traditional polygon positioning algorithm.This algorithm is based on the relationship between the position of reference nodes and the position of unknown node.By selecting optimum reference nodes in the process of calculating the unknown nodes’ position

the more accurate location information can be obtained.The simulation results indicate that the location reference node optimization selection(RNOS)algorithm can meet the requirement of pervasive terminal’s real-time localization and possesses the preferable localization precision.