Reducing Error of Positioning Based on Unstable RSSI of Short Range Communication

Many services that use location information have been proposed; however, improving positioning accuracy in these devices remains an important challenge. The existing conventional positioning method uses trilateration to estimate the target node from three anchor nodes. For short-range communication, such as Bluetooth, the distance between each node is estimated by the received signal strength indicator (RSSI). However, if radio waves are blocked, the positioning estimation error increases because the RSSI value may be reduced signi?cantly. We propose a method to reduce positioning error in an environment with four or more nodes. First, the proposed method estimates the position of the target node relative to three anchor nodes. The positions of the remaining anchor nodes are estimated by two of the three anchor nodes and the target node. The proposed method adjusts the Unit RSSI value such that the difference between the estimated and actual anchor position is minimized. The results of an experiment performed with four anchor nodes demonstrate that the positioning error can be reduced by 37.5% compared to the existing method.