UMTS : The Physical Layer of the Universal Mobile Telecommunications System

It took more than 15 years of research, standardization work, and develop- ment with an enormous effort of manpower to bring third generation (3G) wireless communication systems to life. The first research work on 3G sys- tems started around 1988 [1]. At this time the striking success of second generation (2G) systems, especially of GSM (Global System for Mobile Com- munications), was not yet evident. A substantial part of these early research activities took place in Europe and was sponsored by the European Commis- sion in the course of research programs such as: Research and Development of Advanced Communications Technologies in Europe (RACE-I, RACE-2) and Advanced Communications Technology and Services (ACTS) [2]. Even before these activities, 3G systems were considered in 1992 at the WARC (World Administrative Radio Conference), where 230 MHz of spectrum around 2 GHz was identified for 3G, and in standardization bodies like the ITU (Interna- tional Telecommunications Union) from a global perspective and ETSI (Eu- ropean Telecommunications Standards Institute) in Europe. At the present time 3G networks are deployed or are already operating (e. g. , in Japan the first commercial 3G system started its service in October 2001). Unfortu- nately, the initial idea to create one single 3G standard to allow for seam- less world-wide roaming could not be realized. However, three of the five members of the so-called IMT-2000 (International Mobile Telecommunica- tions, the official acronym for 3G systems) family of standards are based on Wideband-CDMA (Code Division Multiple Access).