In 1977, the Institute of Electrical and Electronics Engineers, known as the IEEE, ratified the 802.11 specification as the standard for Wireless Local Area Networks (WLANs). The specifications originally defined 1 Mbit/s and 2 Mbit/s data transmission rates and a set of basic signaling methods. However, those earlier data transmission rates were too slow to support most business requirements and were ineffective in encouraging WLAN adoption.
Therefore, in 1999 the IEEE ratified the 802.11b standard (or 802.11 High Rate), which provided for data transmission rates up to 11 Mbit/s. In June 2003 the 802.11g standard was ratified to allow for data transmission rates up to 54 Mbit/s.
The 802.11 specification defines a pair of devices: (1) a wireless station—typically a PC with a wireless network interface card (known as NIC); and (2) an access point (known as AP)—which serves as a bridge between the wired and the wireless worlds.
An AP usually has a radio, an Ethernet interface (such as IEEE 802.3), and software meeting the 802.1d “bridging” standard. The AP serves as the wireless network’s base station so that many wireless end stations can get access to the wired network. Wireless end stations, though they vary, typically include 802.11 PC cards and embedded solutions in useful items such as telephone handsets.
The 802.11 standard also defines two modes: the infrastructure mode and the ad hoc mode. In infrastructure mode, the wireless network is made up of at least one AP connected to the wired network infrastructure as well as a number of wireless end stations. The latter is known as a Basic Service Set (BSS). An Extended Service Set (ESS) has two or more Basic Service Sets forming a subnetwork. Because most large companies’ WLANs need access to the wired LAN for functional services (such as file servers, Internet links, and printers), they tend to operate in infrastructure mode.
PCTechGuide.com. Wireless Networks. [Online, December 1, 2002.] PCTechGuide Website. http://www.pctechguide.com/29network_Wireless_networks.htm.