A Distributed Localization System Based on Phase Measurement for Wireless Sensor Networks

We present a localization system based on phase measurement for wireless sensor networks. The system features at least 3 anchor nodes with known locations. The anchor nodes broadcast synchronized reference signal to the location-unknown user nodes. The user nodes measure relative phase offset of reference signals from different anchors, and the relative phase offset indicates relative distance offset between user nodes and anchors. The distance offset can be utilized by hyperbolic localization algorithm, from which the 2-D coordinates of all user nodes can be efficiently calculated by user node itself. The advantage of the proposed method is that the user node itself conducts ranging and localization in a completely distributed manner, with no necessity of information exchange with other user nodes. It thus effectively protects the location privacy of user nodes from radio exposure, while significantly reducing the network overloads.