Abstract
In recent years, applications of positioning have become more and more popular. Since the signals transmitted from global positioning system (GPS) satellites cannot penetrate inside the buildings, there are demands for indoor positioning systems with other technologies. In this thesis, we propose a indoor positioning system based on Bluetooth low energy (BLE) with characteristics of low power, low cost and high portability . The proposed system consists of BLE tags, BLE/WiFi repeaters and a fusion server. The BLE tag in our system is a device which broadcasts BLE beacons. The BLE/WiFi repeaters collect the beacons transmitted from the tag and extract the received signal strength (RSS). The RSS values are then transmitted to our fusion server through Wi-Fi, and the server will estimate the position of the BLE tag with RSS-based positioning algorithm. We propose a indoor positioning algorithm which is a hybrid from received signal strength indication (RSSI)-fingerprint and cell of origin (CoO). Some modifications are made to typical RSSI-fingerprint and CoO algorithm to get better accuracy. To verify the performance of our system, we take two indoor environments into considerate. The first is the rest area of Delta building in National Tsing-Hua University (NTHU). The second is the office of GYRO system company. Each environment is covered by four BLE/WiFi repeaters. The mean error distance of these two environments are 1.2 m and 1.37 m respectively. Moreover, the size of the BLE tag is 1.7 cm in radius and 0.5 cm thick, that can be easily attached to the localization target. Each BLE tag costs 3 US dollars. So it is friendly for those who need large amounts of them for multi-objects positioning. The current consumption of the tag is 50 A which can be used without charge for 136 days with a CR2025 battery.