an example of a game that has this transporting mechanism (and are therefore called IP-based characteristic. services). Hence future mobile-communication networks, Voice: This has the characteristic to require small including the 3G evolution, need to be optimized for amounts of data (voice packets) frequently with no IP-based applications. delay jitter. The end-to-end delay has to be small enough not to be noticeable. 4.2.1.2.3 Wide spectrum of service needs Interactive file download and upload applications: Trying to predict all the services that will be used over the These have the characteristics of requiring low mobile-communication systems 10 years from now is delay and high data rates. very difficult. The technology advancements in the vari- Background file download and upload applications: ous areas enable higher data rate connections, more These have the characteristics of accepting lower memory on local devices, and more intelligent and easy to bit rates and longer delays. E-mail (mostly) is an use man-machine interfaces. Furthermore, the human example of background file download and upload. need of interaction and competition with other humans Television: This has the characteristics of streaming drives more intensive communication needs. All these downlink to many users at the same time requiring combinations point toward applications and services that low delay jitter. The service can tolerate delays, as consume higher data rates and require lower delays com- long as it is approximately the same delay for all users pared to what today's mobile-communication systems can in the neighborhood. The television service has deliver. moderate data rate requirements. However, the relatively low-rate voice service will still A mobile-communication system designed to handle be a very important component of the service portfolio that these services and the services in between will be able mobile-network operators wish to provide. In addition, to facilitate most services (see Figure 4.2-2). Un- services that have 