System Design of WiFi-Signaling Based Accurate Occupancy Detection Scheme

摘要

Indoor location systems are the key technology to providethe location of a human or a device in indoor space. SinceWiFi technology has been spread in various spaces, WiFi isthe practical standard to realize the indoor location systems. Asa receiver can typically find some WiFi access points (APs),indoor location systems use multiple signals from some APs toestimate a position. Initial systems use Received Signal Strength(RSS) as the measurement of distance because RSS decreasesaccording to the distance between AP and a receiver. Recently,more practical service using indoor location systems has beendiscussed. This paper proposes an occupancy detection schemebased on a WiFi-based indoor location system. The proposedscheme tracks users’ smartphone devices as a human location.The location of a human in a room is useful information tomanage human resources efficiently. Therefore, some systemstrack a beacon tag to estimate the location or typical locationsystems use WiFi signals from several APs to estimate alocation. As a result, the conventional systems require a specialbeacon tag or special tracking application to realize the humanlocation system. On the contrary, the proposed system usesusers’ smartphones instead of special devices or applications. Inthis situation, the proposed system must track all WiFi devicesthat do not associate with a WiFi access point. Therefore WiFiAPs cannot detect all users’ devices. The proposed schemefocuses on the WiFi signaling process to detect a user’s deviceand estimates the location of a user’s device. The WiFi signalreceivers detect a probe request message from a user’s devicebecause a probe request message should be transmitted even ifthe user’s device does not associate an AP. We have developeda prototype system to evaluate the performance.