What, technically speaking, is 802.11b and how does it relate to IEEE 802.11? This chapter covers the technology of transmitting data over the airwaves, the process of that transmission, and the topologies and components of wireless networks. Thousands of enterprises worldwide are "cutting the wires" to their LANs to enjoy greater productivity from their unwired workforce. The 802.11b technology also presents the potential to save money on infrastructure (wiring buildings for networks) and telecommunications services.

Because Vo802.11 is VoIP transmitted on 802.11, it is necessary to understand how this transmission medium functions. Just as voice has been transmitted over asynchronous transfer mode (ATM), frame relay, X.25, and the Internet Protocol, it can also be transmitted on 802.11. This chapter discusses how 802.11 works. From this, the reader will gain a better understanding of how 802.11 can be used to transmit voice.

How Does WiFi Work?

A networked desktop computer is connected to a larger network [LAN, widearea network (WAN), Internet] via a network cable to a hub, router, or switch. The computer's network interface card sends zeros and ones down the cable by changing the voltage on the wires from +5V to -5V in a prearranged cadence. WiFi simply replaces these cables with small, low-powered two-way radios. Instead of changing voltage on a wire, it encodes the zeros and ones by laying an alternating radio signal over a constant existing signal, again in a prearranged cadence. The alternating signal encodes zeros and ones on the radio waves. The...