Overview

Take a moment to look around you. Unless you are outside, you should see walls and ceilings decked out in technological artifacts: lighting fixtures, jacks (telephone and data), power outlets, and so forth. They are so common they've become a part of the landscape. Now an invisible artifact is joining this landscape. It provides high-speed, low-cost, low-power, wireless access to the Internet and other networks over a short range. It is Wi-Fi, which is a marketing term that has grown to encompass technology built upon the three latest 802.11 Physical Layer specifications: 802.11a, 802.11b and 802.11g.

In its base set of applications, Wi-Fi provides wireless connectivity via portable devices, including laptops, tablet PCs, handheld computers, personal digital assistants (PDAs), digital cameras, audio and video players, cell phones, headsets, and even portable devices that people can wear on their clothing. Wi-Fi also provides end-users wireless access to a host of new services through a topology referred to as a "wireless local area network" (WLAN), which usually consists of a wired Internet connection and more traditional wired voice and data connections.

Wireless LAN technologies (i.e. the 802.11 series of specifications) emphasize a high data speed and a range that makes using these technologies in a networked environment feasible. Typically, WLANs provide wireless links from portable computing devices to a wired LAN via access points (essentially a wireless hub), but there are also a growing number of stand-alone WLANs.

Now, what many people don't realize is that the wireless LAN's foundation is...