0 kHz (one AMPS carrier) Figure 10.15 Resource allocation in an AMPS system Terrestrial Broadband Wireless Telecommunications Table 10.2 1G standards Standard Countries/region Nordic countries, Switzerland, Holland, Eastern Europe North and South America, Australia C-450 West Germany, Portugal, South Africa Radiocom 2000 France Italy TZ-801, 802, 803 Japan (NTT) JTACS Japan (DDI) Circuit-switching technology was used in 1G mobile systems. An exclusive end-to-end connection between a mobile and a base station and beyond to the telephony network was established and maintained for each call. That is, the radio wave spectrum resources required for a call (e.g. a 25 kHz voice channel) and the public telephony fixed network links, were assigned at the beginning of the call and maintained until the call ended. A number of 1G FDMA system were developed in the late 1970s and early 1980s. A list of these standards is given in Table 10.2. Most major telecommunications manufacturers independently developed analogue FDMA systems, and marketed them to their operator clients. Because of this independent development, little to no interoperability existed between different standards, and therefore no roaming was possible between different operators and countries. However mobile phone services were deemed a success, and policy makers, operators and manufacturers worked together to develop a new generation of mobile communications standards with a more universal reach. Digital technologies were deemed as essential in achieving a higher degree of efficiency. Time Division Multiple Access The growing popularity of mobile telephony, and an increasing need for higher efficiency and quality of wireless communications services by using digital technologies led to the development of a number of new standards in the 1980s. Led by national and regional regula- tors, many manufacturers and operators were brought together to develop more universal stan- dards. These standards are generally classified as the second generation or 2G. Two of the