UMTS architectures

The Universal Mobile Telecommunication System (UMTS) is being developed within Europe as a third generation system for mobile telecommunications. It will complement and, in many cases, provide integration with the Global System for Mobile communications (GSM) which is in service within Europe and increasingly globally. The requirements for UMTS to be commercially viable are discussed. The resultant UMTS system will provide network and service infrastructure convergence for fixed and mobile networks by allowing network operators to flexibly and efficiently offer service to customers irrespective of their access means. This does not imply that fixed and mobile networks will not exist in their own right when UMTS is introduced, but that UMTS will supplement existing systems such as GSM. The paper introduces general cellular concepts and efficiency improvements that could be made over current second generation systems, the proposed high level UMTS network architecture and the different evolution paths to UMTS. This paper is based upon ongoing UMTS standards work in the European Telecommunications Standards Institute (ETSI) and the results of the RACE Mobile Networks (MoNet) project.