Читать книгу Spatial Multidimensional Cooperative Transmission Theories And Key Technologies - Lin Bai - Страница 12

The first generation of mobile communication systems (1G) was born in the 1970s and 1980s when the integrated circuits, microcomputers, and microprocessor technologies were rapidly developed. In 1978, Bell Labs of the United States introduced an analog cellular mobile communication system, extending mobile communication into personal field. In 1983, the US advanced mobile phone service (AMPS)¹ was put into commercial use. The AMPS system employed a 7-cell multiplexing mode and could use “sectorization” and “cell splitting” to increase capacity when needed. At the same time, Europe and Japan had also established their own mobile communication networks, including the UK’s extended total access communication system (ETACS) and Japan’s narrowband total access communication system (NTACS). The wireless communication system of this period mainly used analog modulation and frequency division multiple access (FDMA) technology. There is no doubt that the first generation of mobile communication system has many shortcomings, such as limited user capacity, difficulty in system expansion, mixed modulation methods, inability to achieve international roaming, poor confidentiality, low call quality, and inability to provide data services.