User`s guide

Aironet Wireless Communications, Inc. 3-1 Confidential and Proprietary
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CHAPTER 3 A
Overview of the 802.11 Wireless LAN Protocol
The IEEE 802.11 Wireless LAN Specification addresses only the lowest two layers of the protocol
model. The main intent is to provide a framework such that multiple vendors can design interoperable
products.
When compared to a wired protocol (like 802.3 for ethernet) which guarantees that all stations can
directly communicate with each other, the uncertain nature of wireless communications does not
guarantee that all users will be able to have direct communications with each other. To overcome this
uncertainty, the 802.11 protocol is based on a MAC scheme known as CSMA/CA (carrier sense multiple
access with collision avoidance). CSMA/CA allows for efficient use of the available bandwidth while
arbitrating between all users.
Architecture Overview
Figure 3.1 - Architecture Reference Model
LLC
MAC
Sublayer
MAC Layer
Management
PHY Layer
Management
Station
Management
MAC
PHY
PLCP Sublayer
PMD Sublayer