Improving Accuracy of Localization with Portable APs in Ultra-Narrow-Band-based LPWA Networks

Low-Power Wide-Area networks (LPWA) are useful to collect data from tiny devices distributed in a wide geographic area of land. Since LPWA devices often need to save power consumption and are less functional, localization of devices are addressed as one of the important practical problems. UNB (Ultra Narrow Band)-based LPWA networks such as Sigfox are one of the major LPWA services for IoT applications, which has a long communication range more than 10km. However, due to the long-range communications and the property of UNB-based modulation, it is preferable to use RSSI (Radio Signal Strength Indicator) in localization so that position estimation errors are large. In this paper, we propose a method to improve accuracy of device localization by utilizing portable Access Points (APs). We use a vehicle equipped with a portable AP to collect RSSI measurements. By introducing distance-based weighting technique, we improve the localization accuracy in combination with stationary and portable APs. Through evaluation in Wakayama city, we demonstrated that the portable AP and the new weighting technique effectively work in UNB-based LPWA networks.