802-11a Definition

Also known as Wi-Fi5 (Wi reless Fi delity 5 GHz). The IEEE standard for an 802.11 wireless local area network (WLAN) operating in the 5-GHz range. 802.11a uses coded orthogonal frequency division multiplexing (COFDM), which sends a stream of data symbols in a massively parallel fashion across multiple subcarriers, each of which is 20 MHz wide and is subdivided into 52 subcarrier channels, each of which is approximately 300 KHz wide. Of those subcarrier channels, 48 are used for data transmission, and the remaining 4 for error control. The specific modulation scheme depends on link quality, with the highest link quality employing the most complex technique, which yields the greatest signaling rate.As the link quality deteriorates, the modulation technique ratchets down to the least capable. In order of complexity and yield, those techniques are as follows.
Webster's New World Telecom