Evolution of Wireless LAN

In late 1980s, vendors started offering wireless products, which were to substitute the tra­ditional wired LAN (Local Area Network) products. The idea was to use a wireless local area network to avoid the cost of installing LAN cabling and ease the task of relocation or otherwise modifying the network's structure. When the Wireless LAN (WLAN) was first introduced in the market, the cost per node was quite high and higher than the cost compared to its counterpart in the wired domain. However, as time progressed, the cost per node started dropping making wireless LAN quite attractive. Slowly WLAN started becoming popular and many companies started offering products. The question of inter- operability between different wireless LAN products became critical. IEEE standard committee took the responsibility to form the standard for WLAN. As a result IEEE 802.11 series of standards emerged.

WLAN uses the unlicensed Industrial, Scientific, and Medical (ISM) band that different products can use as long as they comply with certain regulatory rules. These rules cover characteristics such as radiated power and the manner in which modulation occurs. WLAN is also known as Wireless Fidelity or WiFi in short. There are many products which use these unlicensed bands along with WLAN; examples could be cordless telephone, microwave oven etc. There are 3 bands within the ISM bands. These are 900-MHz ISM band, which ranges from 902 to 928 MHz; 2.4-GHz ISM band, which ranges from 2.4 to 2.4853 GHz; and the 5.4 GHz band, which range from 5.275 to 5.85 GHz. 1A^TLAN uses 2.4 GHz and 5.4 GHz bands. WLAN works both in infrastructure mode and ad hoc mode.