ABSTRACT
The WiMAX forum is an industry consortium promoting the Institute of Electrical and Electronic Engineers (IEEE) 802.16 family of standards for broadband wireless access systems. Historically, the first IEEE 802.16 standard (and associated 802.16c profile definitions) addressed primarily line-of-sight (LOS) environments at high-frequency bands (10-66 GHz) via conventional QAM modulated single-carrier techniques. The limited market potential for mm-wave LOS systems resulted in the development of the IEEE 802.16a amendment to support non-line-of-sight (NLOS) modes in radio bands between 2 and 11 GHz. The 802.16-2004 standard [2] (also known as 802.16d) made more radical changes to 802.16 physical layer (PHY) operations for low-frequency (2-11 GHz) bands by adding two orthogonal frequency division multiplexing (OFDM)-based PHY modes:
A 256-point FFT (Fast Fourier Transform) OFDM PHY mode.• A 2,048-point FFT OFDMA (Orthogonal Frequency Division Multiple • Access) PHY mode.
