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Two of the major developments reshaping the telecommunications landscape are
mobile wireless connectivity and the migration of voice telephone services to IP
technology. Those two ideas come together in networks that carry voice services
over a wireless LAN (VoWLAN). The purpose of this text is to provide network
professionals with the technical background and practical guidance needed to
deploy these networks successfully.
That is a tall order in that both wireless LANs and voice over IP (VoIP) are
relatively new technologies and both are advancing at a breakneck pace. We can
place the inception of the wireless LAN (WLAN) market at 1999 with the
ratifi cation of the 802.11b radio link protocol that boosted transmission rates to
11 Mbps. Since then, hundreds of millions of WLAN compatible devices have
been sold around the world and the technology continues to evolve.
The cost of a Wi-Fi interface has dropped from several hundred dollars to
essentially zero; a Wi-Fi card is now a standard component in virtually every
laptop sold. The penetration of that technology is now expanding to cell phones,
PDAs, digital cameras, and other types of consumer electronics. Data rates have
grown to 54 Mbps, and the new 802.11n radio link could push that to hundreds
of millions of bits per second. Along with that we have seen important
developments in security and manageability that make WLANs a trusted
technology element in enterprise environments.