Wireless lan standards

The 802.11 standards cover the physical (PHY) and media access control (MAC) layer definition for local area wireless networking. In the 802.11 standards, wireless local area networks (WLANs) are based on a cellular structure where each cell, under the control of an access point (AP), is known as a basic service set (BSS). The 802.11 standards define two modes of operation for a BSS—the ad-hoc mode and infrastructure mode. The MAC layer is implemented in every 802.11 station, and it enables the station to establish a network or join a pre-existing network and to transmit data passed down by Logical Link Control (LLC). These functions are delivered using two classes of services—station services and distribution system services—which are implemented by the transmission of a variety of management, control, and data frames among MAC layers in communicating stations. The 802.11 standards specify an optional priority-based media-access mechanism—the point coordination function (PCF) that is able to provide contention free media access to stations with time-critical requirements.