A method for transmitting to a direct mobile communications (DMC) device by a user equipment operating in both a cellular mode and a DMC mode includes estimating a first pathloss of a first channel from the user equipment to a base station according to a difference between a known base station transmit power level and a received base station power level, and estimating a second pathloss of a second channel from the user equipment to the DMC device according to a difference between a known DMC device transmit power level and a received DMC device power level. The method also includes setting a transmit power level for transmission to the DMC device according to the first pathloss and the second pathloss, and transmitting a signal to the DMC device at the transmit power level.