Using area judgment to adjust Indoor Positioning

Abstract

Indoor Positioning (IP) has become a hot technology, enabled by the expansion of wireless communications, as a result of the Internet of Things. Several wireless technologies, such as Wi-Fi, ultrasonic, and Bluetooth, can be used to build IP systems. Because of the low power and cost requirements, using Bluetooth Low Energy for IP systems is more popular now than ever before. However, positioning accuracy can be adversely affected by several factors, including environmental interference, temperature, obstacles, transmission distance, and antenna angle. As the distance between transmitter and receiver increase, so the amount of change in the received signal strength indicator (RSSI). However, even when the distance between the transmitter and receiver is constant, a change in the angle between the two antennas is enough to cause RSSI values to differ drastically. This study uses an Android phone to observe the RSSI value of Estimote beacons inside an experimental area divided into six regions. Based on the resulting observations, we are able to correct distance errors due to the different angles and obtain the device's position in the area via triangulation. We find that our calculation of the device's position differs from its actual position by an average of 0.713 meters, but no less than 0.309 meters. The method we propose consistently minimizes the difference between the calculated and actual position of the device, taking into account large angle deviations, and provides stable and accurate indoor positioning information.