Chapter 1 - IEEE 802.11 WLAN systems

Abstract

This chapter elaborates various aspects of IEEE 802.11 WLAN systems. 802.11 WLANs use an entirely different network protocol and are deployed in different topologies. The purpose of a WLAN is primarily to provide LAN connectivity to portable and mobile stations, though fixed-station use is becoming more popular as the technology becomes widely adopted. WLANs provide data communications over radio links, and are subject to all the vagaries of RF propagation and interference that any radio communications system suffers. As radio signals propagate well outside the area covered by the WLAN and could interfere with other radio services, the operation of WLANs is governed by national and international regulations rather than being exclusively limited by technical or market considerations. While the IEEE 802.11 protocol allows for different types of WLAN topologies to be set up, nearly all deployed WLANs comprise two types of stations: clients and access points. The physical or PHY layer deals with the transmission and reception of radio signals, and is further divided into the physical media-dependent portion and the PHY-layer convergence protocol. It is found that the Medium Access Control (or MAC layer) deals with the exchange of suitably formatted packets.