8 B] Explain the IEEE 802.11 Wi-Fi stack and Wi-Fi deployment architecture.
• Wi-Fi or WiFi is technically referred to by its standard, IEEE 802.11, and is a wireless technology for wireless local area networking of nodes and devices built upon similar standards (Figure 4.25).
• Wi-Fi utilizes the 2.4 GHz ultra-high frequency (UHF) band or the 5.8 GHz super high frequency (SHF) ISM radio bands for communication. For operation, these bands in Wi-Fi are subdivided into multiple channels. The communication over each of these channels is achieved by multiple devices simultaneously using time-sharing based TDMA multiplexing. It uses CSMA/CA for channel access.
• Various versions of IEEE 802.11 have been popularly adapted, such as a/b/g/n.
The IEEE 802.11a achieves a data rate of 54 Mbps and works on the 5 GHz band using OFDM for communication. IEEE802.11bachieves a data rate of 11 Mbps and operates on the 2.4 GHz band. Similarly, IEEE 802.11g also works on the 2.4 GHz band but achieves higher data rates of 54 Mbps using OFDM.
The newest version, IEEE802.11n, can transmit data at a rate of 140 Mbps on the 5 GHz band.
Wi-Fi devices can network using a technology referred to as wireless LAN (WLAN), as shown in Figure 4.26. A Wi-Fi enabled device must connect to a wireless access point, which connects the device to the WLAN. WLAN is then responsible for forwarding the messages from the devices to and fro between the devices and the Internet.
