WiMAX is short for Worldwide Interoperability for Microwave Access and it is defined by the IEEE 802.16 Working Group. Although first intended for fixed applications, the initial WiMAX standards have evolved to form the basis for mobile WiMAX as well.
The current version of the fixed WiMAX standard is 802.16-2004, sometimes also referred to as 802.16d. It is essentially frequency independent, allowing also nonline-of-sight (NLOS) operation in the lower end of the frequency range (frequencies below 3 GHz, according to Richardson (2006)). The radio access interface is based on orthogonal frequency division multiplexing (OFDM) with 256 subcarriers, although OFDMA2048 and single carrier access modes are included in the 802.16-2004 standard as alternatives. OFDM allows good resistance to interference and multipath fading.
