14.4 WIRELESS LOCAL AREA NETWORKS (WLANs)

Wireless Local Area Networks (WLANs) provide network connectivity using radio transmission rather than fixed cabling. WLANs may function as an alternative to wired Ethernet within a building or campus, or as a complementary access layer integrated with a wired distribution system. Unlike wired Ethernet, which uses point-to-point full-duplex links, WLANs operate over a shared radio channel and must therefore coordinate medium access among multiple transmitting stations.

Several wireless LAN standards were developed in the late 1990s. One of the most significant alternatives was HIPERLAN/2, a European WLAN standard developed by ETSI. Although technically competitive with early OFDM-based IEEE 802.11 systems, HIPERLAN/2 did not achieve widespread global adoption and was eventually eclipsed by the IEEE 802.11 family. Today, the dominant WLAN standards are defined by IEEE 802.11 and are commonly referred to as Wi-Fi, a certification trademark administered by the Wi-Fi Alliance.