A transmitting communication device may iteratively adjust its transmit power, and may estimate, based on iterative transmit power adjustment, relative location of a receiving communication device. The transmit power may be initialized to a maximum value, and the transmit power may be iteratively reduced until connectivity with the receiving communication device is lost. The loss of connectivity may be determined based on reception of responses to ping messages transmitted by the transmitting communication device. The transmitting communication device may authenticate the receiving communication device and/or a user of the receiving communication device. The authentication may comprises utilizing transmit power adjustment and/or relative location estimation therefrom to ensure that a separation between the devices does not exceed a maximum value. The transmitting communication device may generate location info associated with the receiving communication device based on the relative location estimation, and may communicate the location info to a location server.