2
Background
2.1 Evolution of Cellular Systems
Mobile communications were originally introduced for military applications. The concept of a cellular network was taken into commercial use much later, near the beginning of the 1980s, in the form of the Advanced Mobile Phone System (AMPS) in the USA and in the form of the Nordic Mobile Telephone system (NMT) in northern Europe. These first-generation cellular systems were based on analogue technologies. Simultaneous access by many users in the same cell was provided by the Frequency Division Multiple Access (FDMA) technique. Handovers between different cells were already possible in these systems and a typical use case was a phone call from a car.
The second generation of mobile systems (2G) was introduced roughly a decade later, at the beginning of the 1990s. The dominant 2G technology has been the Global System for Mobile (GSM) communications, with more than three and a half billion users worldwide at the time of writing. The second generation introduced digital information transmission on the radio interface between the mobile phone and the base station. The multiple access technology is Time Division Multiple Access (TDMA).
The second generation provided an increased capacity of the network (owing to more efficient use of radio resources), better speech quality (from digital coding techniques) and a natural possibility for communicating data. Furthermore, it was possible to use new types of security feature, compared to analogue ...
