Field Guide to Wireless LANs for Administrators and Power Users, A

MAC/PLCP Interactions

The PLCP is used to specify certain properties of the subsequent frame, most importantly its speed (which is intimately related to the modulation that is used to transmit the digital data over the inherently analog WM). By using PLCP, each transmitted PSDU is endowed with a label that lets it be transmitted at any of the valid speeds in the Operational Rate Set as specified by the AP.

The short-format PLCP header was introduced as an optional performance-enhancing feature in the IEEE 802.11b-1999 standard. The forthcoming IEEE 802.11g standard, if approved, will be the first 2.4 GHz PHY to mandate support for the short-format PLCP header.^[14] The usage of the optional Short Preamble primarily affects the efficiency of sending ...