Implementation of Indoor Positioning Using Signal Strength from Infrastructures

Real time location system is not a brand new technology. The most typical approach is using global position system (GPS). However, GPS can only be used outdoors. It is unable to work completely indoors or in an environment with obstacles. Therefore, the development related to indoor position technology is quite important. In the system developed in this study, it makes use of Received Signal Strength Index value of low-power active RFID (Radio Frequency Identification) for movement detection. Besides, it adopts ZigBee wireless transmission technology as reference nodes for positioning detection. Information gathered by reference points is delivered to the server through the Internet. All positioning information is computed by the server. Positioning algorithm uses the average values of signals in its operation. The advantage is to compare many average values with the closing nodes in order to locate the closest position node for the mobile device and reduce the multi-path interference which is caused by other environmental factors. Positioning results can be accessed through the networked computer or mobile device with WiFi functionality. The experimental results are more stable than other positioning algorithms, and the installation of the system is more convenient.