UMTS Services and Applications

The best known new feature of UMTS is higher user bit rates: on circuit-switched connections 384 kbps, and on packet-switched connections up to 2 Mbps, can be reached. Higher bit rates naturally facilitate some new services, such as video telephony and quick downloading of data. If there is to be a killer application, it is most likely to be quick access to information and its filtering appropriate to the location of a user: see Figure 2.1. Often the requested information is on the Internet, which calls for effective handling of TCP/UDP/IP traffic in the UMTS network. At the start of the UMTS era almost all traffic will be voice, but later the share of data will increase. It is, however, difficult to predict the pace at which the share of data will start to dominate the overall traffic volume. At the same time that transition from voice to data occurs, traffic will move from circuitswitched connections to packet-switched connections. At the start of UMTS service not all of the Quality of Service (QoS) functions will be implemented, and therefore delaycritical applications such as speech and video telephony will be carried on circuit-switched bearers. Later, it will be possible to support delay-critical services as packet data with QoS functions. Compared to GSM and other existing mobile networks, UMTS provides a new and important feature, namely it allows negotiation of the properties of a radio bearer. Attributes that define the characteristics of the transfer may include throughput, transfer delay and data error rate. To be a successful system, UMTS has to support a wide range of applications that possess different quality of service (QoS) requirements. At present it is not possible to predict the nature and usage of many of these applications. Therefore it is neither possible nor sensible to optimise UMTS to only one set of applications. UMTS bearers have to be generic by nature, to allow good support for existing applications and to facilitate the evolution of new applications. Since most of the telecommunications applications today are Internet or N-ISDN applications, it is natural that these applications and services dictate primarily the procedures for bearer handling.