125 Copyright © 2010, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. Chapter 7 User Experience in 4G Networks Pablo Vidales Deutsche Telekom Laboratories, Germany Marcel Wältermann Deutsche Telekom Laboratories, Germany Blazej Lewcio Deutsche Telekom Laboratories, Germany Sebastian Möller Deutsche Telekom Laboratories, Germany abstract Forthcoming 4G networks will enable users to freely roam across different communication systems. This implies that formerly independent wireless and wired technologies will be integrated to deliver transparent access to a plethora of mobile services and applications. This will also involve changes in the user’s experience mainly derived from (1) mobility across heterogeneous technologies, (2) drastic changes in the underlying link conditions, and (3) continuous adaptation of applications, e.g. fexible coding schemes. This chapter presents a detailed study of these so far unknown phenomena arising in the context of 4G networks. Current instrumental models employed to estimate user perception, such as PESQ (ITU-T Rec. P.862, 2001) for predicting the quality of transmitted speech, were designed to measure conditions that are common in today’s wireless and wired systems. However, it is expected that new conditions encountered in 4G networks are not going to be accurately handled by today’s models. Thus, they need to be adjusted, or new models should be proposed in order to predict the perceptual infuence of new phenomena such as the three aspects aforementioned. The authors undertook this task and designed a novel methodology and experimental setup to measure user perception in future 4G networks. Moreover, the authors carried out an extensive set of subjective tests to accurately quantify user perception and derive conclusions for optimal user experience in 4G networks. These processes and initial results are included in this chapter. DOI: 10.4018/978-1-61520-674-2.ch007