Indoor localization for Wi-Fi devices by cross-monitoring AP and weighted triangulation

A novel indoor localization method for Wi-Fi devices such as smart phones is presented. With an indoor path loss model, the distance between a mobile device (MD) and an access point (AP) can be estimated form the received signal strength (RSS). Then, least-squared-error (LSE) triangulation yields the position of the MD. Though indoor channel characteristics are highly fluctuating with perturbations, a reference point (RP) can be used to compensate for channel instability. We present two contributions: cross monitoring AP and weighted triangulation. Cross monitoring AP removes the need of deploying RPs since it can play the dual role of a regular AP and a RP. Weighted triangulation yields improvement in the accuracy of LSE estimation of the MD position. Experimental results show weighted triangulation with cross monitoring AP provides indoor localization with an error less than 2 meters.