A wireless local area network (WLAN) is a wireless computer network that links two or more devices using wireless communication within a limited area such as a home, school, computer laboratory, or office building. This gives users the ability to move around within a local coverage area and yet still be connected to the network. Through a gateway, a WLAN can also provide a connection to the wider Internet.

Most modern WLANs are based on IEEE 802.11 standards and are marketed under the Wi-Fi brand name.

Wireless LANs have become popular for use in the home, due to their ease of installation and use. They are also popular in commercial properties that offer wireless access to their employees and customers.

802.11 Architecture

The 802.11architecture defines two types of services and three different types of stations

802.11 Services The two types of services are

1. Basic services set (BSS)
2. Extended Service Set (ESS)

Basic Services Set (BSS)

• The basic services set contain stationary or mobile wireless stations and a central base station called access point (AP).

• The use of access point is optional.

• If the access point is not present, it is known as stand-alone network. Such a BSS cannot send data to other BSSs. This type of architecture is known as adhoc architecture.

• The BSS in which an access point is present is known as an infrastructure network.

* Extend Service Set (ESS)*

An extended service set is created by joining two or more basic service sets (BSS) having access points (APs).These extended networks are created by joining the access points of basic services sets through a wired LAN known as distribution system.