Proposals on UMTS system configuration

The Universal Mobile Telecommunications System (UMTS) is a third generation mobile system, which is expected to be launched within the next 10 years. It is expected to offer global coverage (by using the universal personal standard), services up to multimedia, and air interface bit rates up to 2 Mbps through all personal, business and residential modes. Therefore, UMTS is expected to be an integration of mobile and fixed networks by using hierarchical layered cell structures. There are many research programmes that are focussing on UMTS and the possible scenarios of its implementation. One of them is the Advanced Communications Technologies and Services (ACTS), which is the successor of RACE. UMTS has to be economic viable and 'future-proof' to be able to support forthcoming services. Hence, any possible launch schemes have to take into account the fact that some particular second generation systems have proved to be very popular and constitute serious investments. For these reasons, they cannot be discarded. An analytical review of the most important existing candidate schemes are presented.