o deliver performance over significant distances (tens of metres), given an understanding of the characteristics of Ir transmitters, detectors and infrared propagation. This page intentionally left blank WIRELESS LAN IMPLEMENTATION Introduction Wireless networking technology at the local area scale is perhaps the most widespread, most commercially significant and most well developed of all wireless networking technologies. In less than a decade since the ratification of the IEEE 802.11a and b standards in 1999, some 200 million 802.11 chipsets have been shipped, a business sector has grown to an estimated turnover in excess of $800 million (chipset cost alone) in 2005, and the standard has developed to the point where a 600- fold increase in data capacity, vehicular speed roaming and mesh networking are now on the horizon. Part III looks at the technologies and practical considerations that underpin successful wireless LANs. The main technical features of wireless LAN standards are described in Chapter 6. This is an area now firmly dominated by the IEEE 802.11 standards, starting with the original 802.11b based Wi-Fi, and now including the improved security features of 802.11i and the upcoming enhancements to throughput and mobility in progress with 802.11n, r and S. Non-IEEE WLAN standards are also reviewed, the brevity of this section being a clear indication of the dominance of the IEEE standards on the local area scale. Chapter 7 covers the implementation of WLANs, from the point of view of a medium scale corporate network, starting with the definition of user Part Three and technical requirements, through planning and installation to operation and support. This chapter concludes with a case study that looks at the specific requirements for a voice over WLAN (VoWLAN) application. Technologies providing security for wireless LANs are described in Chapter 8, including the most recent encryption and authentication mechanisms of 802.11i. Practical WLAN security measures are then described, including checklists co