A method for filling a WiMAX downlink frame by the base station of a WiMAX network, wherein the downlink MAC Protocol Data Units (MPDUs) are fitted into the WiMAX downlink frame by means of a DL-MAP scheduler, which allows the concatenation of downlink MPDUs from different connections in single bursts, the bursts having a rectangular shape in terms of the two dimensions—OFDMA (Orthogonal Frequency Division Multiple Access) symbols and subchannels—of a WiMAX downlink frame, is characterized in that the DL-MAP scheduler is configured in a way that it considers the concatenation of downlink MPDUs from different connections in single bursts based on the available and/or the remaining free space in the WiMAX downlink frame, such that it simplifies the DL-MAP scheduler task of filling the WiMAX downlink frame minimizing the amount of wasted radio resources.