Beacon devices transmit beacon messages to alert an application on a mobile user device of the Beacon device's proximity. A Received Signal Strength Indication (RSSI) field may indicate the power level at which the beacon message was received at the mobile device. Where the transmission power of the beacon device is standardized, the application can infer the distance between the mobile user device the beacon device based upon the RSSI field. By considering successive RSSI values over time while the mobile device is in motion, in conjunction with GPS information for the mobile device, the location of the beacon device relative to the mobile device may be inferred. Multiple mobile devices may be used together to infer the beacon device's position.