Overview

The ability to support voice services over a wireless LAN is important, but the functionality of that solution would increase exponentially if we could integrate that capability with a cellular service. Solutions that are geared toward merging those two environments are referred to as Fixed-Mobile Convergence (FMC). The ultimate solution would be one where the user could place a free call over the WLAN, and then have that call handed off to the cellular network when he or she moves out of range.

While there has been considerable interest in Wi-Fi/cellular integration, from the cellular carrier s standpoint there are challenges on two fronts: technology and marketing. From a technical standpoint, Wi-Fi and cellular networks use completely different technologies, and the task of handing off calls between the two is not trivial. The bigger challenge is on the marketing front, as the cellular carriers will have the primary say in whether or not these offerings come to market; thus far they have been decidedly lukewarm on the idea of converged offerings.

Faced with that reluctance, the industry has responded with a bevy of products that simulate integration but require no support from the cellular carriers. The simplest of these are handsets that include both Wi-Fi and cellular capability, but provide no ability to hand off calls between the networks. While these offer the benefit of carrying one device instead of two, this is a far cry from a truly integrated network offering.

In this chapter we will begin with a...