Apparatus and method for controlling transmission power

An apparatus and method are provided for controlling a transmission power of a wireless communications device to comply with an output energy limit during a measurement period, including calculating a target output energy based on a communications channel; calculating a first average output energy corresponding to a previous period having a duration substantially equal to the measurement period; calculating a second average output energy by low-pass-filtering the target output energy and the first average output energy; and limiting the transmission power of the wireless communications device based on an energy margin between the output energy limit and the second average output energy.