Directional Beaconing: A Robust WiFi Positioning Method Using Angle-of-Emission Information

WiFi-based positioning has been widely used because it does not require any additional sensors for existing WiFi mobile devices. However, positioning accuracy based on radio signal strength is often influenced by noises, reflections, and obstacles. The Time-of-Arrival (TOA) or Angle-of-Arrival (AOA) methods may be used, but both require additional sensing mechanisms and cannot be applied to existing WiFi mobile devices. In this paper, we propose a new WiFi-based positioning method called directional beaconing. This method uses the Angle-of-Emission (AOE) method instead of the AOA. Using this method, access points (APs) emit beacon signals through rotating directional antennas with angle information encoded in beacons. WiFi devices estimate the direction and distance to the AP by receiving and decoding these beacons. This method integrates the advantages of the AOA and signal strength methods without requiring additional sensors. We constructed revolving directional APs and verified positioning accuracy is improved using the proposed method.