System Design of WiFi-Signaling Based Accurate Occupancy Detection Scheme

Yukina Miwa, Akari Ushiyama, Hijiri Komura, Katsuhiro Naito

Indoor location systems are the key technology to provide the location of a human or a device in indoor space. Since WiFi technology has been spread in various spaces, WiFi is the practical standard to realize the indoor location systems. As a receiver can typically find some WiFi access points (APs), indoor location systems use multiple signals from some APs to estimate a position. Initial systems use Received Signal Strength (RSS) as the measurement of distance because RSS decreases according to the distance between AP and a receiver. Recently, more practical service using indoor location systems has been discussed. This paper proposes an occupancy detection scheme based on a WiFi-based indoor location system. The proposed scheme tracks users’ smartphone devices as a human location. The location of a human in a room is useful information to manage human resources efficiently. Therefore, some systems track a beacon tag to estimate the location or typical location systems use WiFi signals from several APs to estimate a location. As a result, the conventional systems require a special beacon tag or special tracking application to realize the human location system. On the contrary, the proposed system uses users’ smartphones instead of special devices or applications. In this situation, the proposed system must track all WiFi devices that do not associate with a WiFi access point. Therefore WiFi APs cannot detect all users’ devices. The proposed scheme focuses on the WiFi signaling process to detect a user’s device and estimates the location of a user’s device. The WiFi signal receivers detect a probe request message from a user’s device because a probe request message should be transmitted even if the user’s device does not associate an AP. We have developed a prototype system to evaluate the performance.

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