WiMAX Technical specifications of 802.16a

WIMAX 802.16 operates at up to 124Mbps in the 28MHz channel (in 10-66GHz), 802.16a at 70Mbps
in lower frequency, 2-11GHz spectrum. Fundamental technologies in 802.16a OFDM Support for OFDM (orthogonal frequency division multiplexing), which can continue to be implemented in various ways by different operators (the precise variant of OFDM can often be their key differentiator).

Fundamental technologies in 802.16a
OFDM
Support for OFDM (orthogonal frequency division multiplexing), which can continue to be implemented in various ways by different operators (the precise variant of OFDM can often be their key differentiator). OFDM is well established and is incorporated in some new generation carrier services as well as being fundamental to digital TV. It transmits multiple signals simultaneously across one cable or wireless transmission path, within separate frequencies, with the orthogonal element spacing these frequencies to avoid interference. It is also supported in the 802.11a WLAN standard.

802.16a has three PHY options: an OFDM with 256 sub-carriers – the only option supported in Europe by the ETSI, whose rival HiperMAN standard is likely to be subsumed into WiMAX; OFDMA, with 2048 sub-carriers; and a single carrier option for vendors that think they can beat multipath problems in this mode. OFDM will almost certainly become dominant in all wireless technologies including cellular and its industry body, the OFDM Forum, is a founder member of WiMAX Forum.

WIMAX Support for Smart Antenna
Smart antenna mechanisms are one of the most important methods of improving spectral efficiency in non-cellular wireless networks. 802.16 standards allow vendors to support a variety of these mechanisms, which can be a key performance differentiator.