이동노드의 RSSI를 활용한 실내 위치 인식 시스템 개발

Abstract

In this thesis, more accurate and efficient indoor location-aware system, which uses Zigbee protocol of short-range wireless communications technology and the technique of selecting RSSI(Received Signal Strength Indication), is proposed. There are several methods in an indoor location-aware approach using the RSSI values. First of all, the distances among three fixed nodes having predetermined coordinates and a mobile node are measured. With three computed distance values, the final coordinate of a mobile node can be obtained. Among many distance measuring methods, typical one is to use triangulation. But the measured or calculated coordinates of a mobile node through the triangulation have a lot of errors. The RSSI values are irregularly measured due to several environmental causes. Thus, the database, which is the reference point every distance of RSSI, should be built up. The RSSI values at every distance are measured and stored using the fingerprint method. The distances on each node are measured with the stored values. But the received RSSI value should be stabilized in environmental causes for more accurate indoor location-awareness. In this thesis, this method choosing the node having reliable RSSI values based on the reliability of the signal is proposed for the more accurate indoor location-awareness when the distance is calculated using RSSI values. To find final coordinate, the determining method of coordinate of a mobile node using the EKF instead of triangulation is proposed.