A Hybrid RSSI-based Indoor Localization Scheme in Wireless Sensor Networks

• Main Authors: Yu-Tso Chen, 陳宥佐
• Other Authors: Yeim-Kuan Chang
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/23634532353998865949

碩士 === 國立成功大學 === 資訊工程學系碩博士班 === 97 === For the various applications in home automation, the service system requires to precisely estimate user’s locations by certain sensors. It is considered as a challenge to automatically serve a mobile user in an indoor environment. However, indoor localization cannot be carried out effectively by the well-know Global Positioning System (GPS). In recent years, Wireless Sensor Networks (WSNs) are thus popularly used to locate a mobile object in an indoor environment. Some physical features are widely discussed to solve indoor localization in WSNs. In this paper, we inquired about the RSSI-based solutions for indoor localization, and proposed a new hybrid-styled Closer Tracking Algorithm (CTA) to locate a mobile user in an indoor environment. Under the proposed CTA, a mode-changed operation was designed to automatically switch the Approximately Closer Approach (ACA) and the Real-time Tracking (RTT) methods according to the pre-defined thresholds, which we had tuned. At the same time, we designed the movable reference nodes to reduce the uncovered ranges of the RTT part for increasing the accuracy. The proposed CTA was evaluated by using ZigBee CC2431 modules. In the experimental results, the CTA can properly select an adaptive mode to improve the localization accuracy with high confidence. Furthermore, the accuracy can be improved by the deployment and movement of the reference nodes. The results showed that the proposed CTA can accurately determine the position with error distance less than 1 meter. At the same time, the CTA has at least 90% precision when the distance is less than one meter.