In the final chapter, we will look at some of the likely future developments of UMTS. We begin with the IP multimedia subsystem, which was introduced into the 3GPP specifications in release 5, and is intended for the delivery of real time, packet switched services to the user. We continue with a look at the long term evolution of UMTS, which is intended to be part of release 8, and will involve changes to the radio interface that will supply the user with much higher data rates than before. We conclude with an overview of the process for defining fourth generation systems, and a look at some of the likely candidates.

The IP multimedia subsystem

The IP multimedia subsystem (IMS) is an extra component of the fixed network. Its main objective is to deliver real time services such as voice and video over the core network's packet switched domain, which have not been supported by previous implementations of UMTS. This section describes the objectives and architecture of the IP multimedia subsystem. It then gives an overview of the protocols and operational procedures that it uses, and describes the services that have been defined for use on the IMS.

Objectives

The IMS is intended to bring three main benefits to network operators and to the user.

First, the IMS provides good end-to-end quality of service for packet switched data streams.