TABLE OF CONTENTS In Chapter 7, we described the service model intended for the integrated VoWiFi/3G application. The design of this service model makes use of many of the modeling methodologies discussed in Chapter 5, and it also reflects a lot of the network aspects of the integrated VoWiFi/3G technology detailed in Chapter 6. From a modeling perspective, we have shown how the general service model concept can theoretically be applied to provide operators with a unified approach to solving the complicated service assurance problem.
In this chapter, we take two additional steps to illustrate how the VoWiFi/3G service model is applied in a practical operations environment. First, we look at practical scenarios involving the most commonly encountered service-quality problems of an integrated VoWiFi/3G network described from a user perspective. Some of these voice-quality problems are typical quality problems documented in the literature. For example, while the echo problem is well known and generally well controlled in the PSTN, it reappears differently in a VoWiFi/3G network. The nature of the echo problem changes as a result of the artifacts introduced by the IP packet network. Consequently, many known theories and solutions behind echo modeling and analysis from the PSTN need to be modified to match new network scenarios. Other service problems are manifestations of the problems in the new WiFi or cellular radio environment. Examples include RF interference and handoff-related performance problems. These are relatively new problems that the industry is still grappling to understand. No matter what the causes, having...
