The worldwide interoperability for microwave access (WiMAX) extends the transmission rate and range of wireless communications beyond the limits of existing technologies while allowing for heterogeneous traffic transmissions. To achieve all these goals, qualified protocols for WiMAX should effectively utilize the spectrum and overcome the deficits of wireless channel while maintaining a satisfactory level of heterogeneous services for users. WiMAX supports air interfaces based on orthogonal frequency division multiplexing (OFDM) which is a robust and flexible technique for transmissions and resource allocations, respectively, over wireless channel. The basic characteristics of OFDM that mitigate the wireless channel impairments are stated in this chapter.Moreover, several resource allocation schemes for subcarrier and power allocation problem in OFDM-based networks are surveyed that provides a deep insight into the problem. Besides, a resource allocation scheme for WiMAX is presented that considers the heterogeneous requirements of WiMAX users and the utilization of scarce resources simultaneously.