Wireless Local Area Networks (WLANs) are designed to provide wireless access in areas with a typical range up to 100 meters and, are used mostly in home, school, computer laboratory, or office environments (Figure 1.6). This gives users the ability to move around within a local coverage area and still be connected to the network [2,5]. WLANs are based on IEEE 802.11standards, marketed under the Wi-Fi brand name. Due to competition, other standards such as HiperLAN never received much commercial implementation. IEEE 802.11 was simpler to implement and made it faster to the market. The complete family will be revised in more detail in section 4.
The IEEE 802.11 is a family of different standards for wireless local area networks. The IEEE 802.11b was the first accepted standard, supporting up to 11 Mbps in the 2.4 GHz unlicensed spectrum band. Then, the IEEE 802.11g standard was designed as a higher-bandwidth successor to the IEEE 802.11b. An IEEE 802.11g access point will support 802.11b and 802.11g clients. Similarly, a laptop with an IEEE 802.11g card will be able to access existing 802.11b access points as well as new 802.11g access points. That is because wireless LANs based on 802.11g will use the same 2.4-GHz band that 802.11b uses. The maximum transfer rate for the IEEE 802.11g wireless link is 54 Mbps, but it will automatically back down from 54 Mbps when the radio signal is weak or when interference is detected.