In this tutorial, we'll take a look inside the 802.11a PHY Layer, which uses orthogonal frequency division multiplexing (OFDM) technology to support operation of up to 54Mbps data rates in the 5GHz band.

The IEEE (define) 802.11 standard includes a common Medium Access Control (MAC) Layer, which defines protocols that govern the operation of the wireless LAN. In addition, 802.11 comprises several alternative physical layers that specify the transmission and reception of 802.11 frames. Let's take a closer look at the 802.11b Physical Layer, which uses direct sequence spread spectrum (DSSS) (define) technology to support operation of up to 11Mbps data rates in the 2.4GHz band.

The 802.11 standard ensures that all stations, both radio-based network interface cards (NICs) and access points, implement access methods for sharing the air medium. When installing wireless LANs (WLAN), most people don't give much thought to these mechanisms.

In addition to data frames that carry information from higher layers, 802.11 includes management and control frames that support data transfer. The beacon frame, which is a type of management frame, provides the "heartbeat" of a wireless LAN, enabling stations to establish and maintain communications in an orderly fashion.