11.10 Summary

The addition of wireless capabilities allows LANs to be extended without the use of wires or cables, thus enabling untethered communications. The other significant advantage is inherent mobility for the users.

The IEEE introduced the standards for local area networks using the 802 standards. The standards were enhanced to also include wireless LAN (WLAN) standards under the 802.11 umbrella. The 802.11 family continues to use the same logical link control (LLC) layer as the other wired LAN systems.

The IEEE introduced the 802.11 standards initially, followed by other standards such as 802.11b and 802.11a that provide higher data throughputs. 802.11 also introduced a common architecture model that includes the independent base station subsystems (IBSSs) or the infrastructure base station subsystems or simply BSS. The BSS includes the wireless stations , which are coordinated by an access point (AP). A distributed system allows mobility and also forms the backbone network to provide extended coverage.

IEEE 802.11 allowed several physical layer mechanisms, such as spread troduced, only direct sequence spread spectrum (DSSS) was allowed and spectrum and infrared techniques. When the higher data rate 802.11b was inachieved data rates of up to 11 Mbps. 802.11a uses the OFDM technique in the new 5 Ghz band to achieve peak data rates of up to 54 Mbps.

The MAC layer provides consistent and fair access to the wireless medium. Several wireless-specific features, such as added reliability, security, and contention resolution were added for the IEEE 802.11 family.

The life of an 802.11 station requires operations to scan, select, authenticate, and associate itself with the IEEE 802.11 system. To facilitate roaming, the IEEE 802.11 standards have defined mechanisms such as reassociation to refresh the 802.11 station's location within a WLAN system.

The applications of IEEE 802.11 WLAN, such as home versus enterprise versus public WLANs, may dictate the key factors to be considered and prioritized for deployment. Several factors, such as cost, range, throughput, mobility, and security, need to be considered and the appropriate decisions made based on service affecting features.