Broadband Wireless Access (BWA) is gaining interest due to the increasing demand of high-quality mobile wireless systems. In this context, the IEEE 802.16 standard, and particularly its OFDMA physical transmission mode, is one of the most promising and researched technologies. In OFDMA, data have to be mapped into a time-frequency matrix before the actual transmission. Efficiency, power consumption and QoS factors should be taken into account by mapping algorithms. In this paper, we focus on the OFDMA resource allocation problem in WiMAX networks.