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]) technology to support operation of up to 11Mbps data rates in the 2.4GHz band.

As with other 802.11 Physical layers, 802.11b includes Physical Layer Convergence Procedure ([PLCP]) and Physical Medium Dependent ([PMD]) sub-layers. These are somewhat sophisticated terms that the standard uses to divide the major functions that occur within the Physical Layer. The PLCP prepares 802.11 frames for transmission and directs the [PMD] to actually transmit signals, change radio channels, receive signals, and so on

* (http://www.wi-fiplanet.com/tutorials/article.php/2107261 802.11B PHY revealed)

||''' Data Rate '''||''' Modulation Technology '''||
|| 11Mbps    || [CCK]                 ||
|| 5.5Mbps   || [CCK]                 ||
|| 2 Mbps    || [QPSK]                ||
|| 1 Mbps    || [BPSK]                ||
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