 in the 1890s, the road to truly mobile quencies, which became fundamental to all subsequent radio communication has been quite long. To understand mobile-communication systems. Commercial mobile the complex third-generation (3G) mobile-communica- telephony continued to be car-borne for many years be- tion systems of today, it is also important to understand cause of bulky and power-hungry equipment. In spite of where they came from and how cellular systems have the limitations of the service, there were systems evolved from an expensive technology for a few selected deployed in many countries during the 1950s and 1960s, individuals to today's global mobile-communication sys- but the users counted only in thousands at the most. tems used by almost half of the world's population. These first steps on the road of mobile communication Developing mobile technologies has also changed, from were taken by the monopoly telephone administrations and being a national or regional concern, to becoming a very wire-line operators. The big uptake of subscribers and complex task undertaken by global standards-developing usage came when mobile communication became an in- organizations such as the Third Generation Partnership ternational concern and the industry was invited into the Project (3GPP) and involving thousands of people. process. The first international mobile communication system was the analog NMT system (Nordic Mobile Tele- phony) which was introduced in the Nordic countries in 4.1.1 History and background of 3G 1981, at the same time as analog AMPS (Advanced Mobile Phone Service) was introduced in North America. Other The cellular technologies specified by 3GPP are the most analog cellular technologies deployed worldwide were widely deployed in the world, with the number of users Total Access Communications System (TACS) and passing 2 billion in 2006. The latest step being studied Japanese-Total Access Communication System (J-TACS). and developed in 3GPP is an evolution of 3G into an They all had in common that the 