An Improved Point-in-Triangulation Localization Algorithm Based on Cosine Theorem

Self-localization of sensor nodes is one of the important technologies in wireless sensor networks. APIT is a range-free localization algorithm; it has the advantages of high localization accuracy and low communication overhead. However, the localization coverage of APIT is low, and when the proportion of anchor nodes is low, APIT is prone to OutToIn and InToOut error. To solve the above problems, this paper proposed a new point-in-triangulation test method based on cosine theorem according to APIT's basic idea to prevent OutToIn and InToOut error, and added RSSI model to locate the unknown nodes which are judged outside the triangles through trilateral measurement method to improve the localization coverage. Simulation results shows that compared with APIT algorithm, the new algorithm has higher localization accuracy and coverage.