第一代移动通信系统

第一代移动通信系统（1G）是模拟制式的蜂窝移动通信系统，主要提供话音服务。

The first generation of mobile communication systems ( 1G ) was analog cellular system for mobile communication standard with the main voice services .

第一代蜂窝移动通信系统几乎没有采用任何安全机制来保护运营商和用户。

The first Generation of cellular mobile communication systems contained few if any security measures to protect the system operator and users .

自20世纪90年代，蜂窝移动通信从第一代模拟蜂窝移动通信系统发展成第二代的数字移动通信系统。

1990s , Cell mobile communication system develop the second generation of digital mobile communication system into while being the first generation of mobile communication .

自20世纪80年代中期以来，蜂窝移动通信已从第一代的模拟蜂窝移动通信系统发展到了第二代的数字蜂窝移动通信系统，并正在向第三代蜂窝移动通信系统演进。

Since the mid of 1980 's , cellular mobile communications have developed from the first generation analog cellular mobile communications systems to the second generation digital cellular mobile communications systems . Now they have been evolved into the third generation cellular mobile communications systems .

第一章介绍了移动通信发展状况和发展趋势，阐述了第一代移动通信系统、第二代移动通信系统、第三代移动通信系统、第四代移动通信系统的特点，以及未来移动通信发展状况。

Chapter I introduced the developments and trends of mobile communication , introduced the characteristics of the first generation of mobile communications systems , the second generation of mobile communications systems , 3G mobile communications systems and fourth-generation mobile communication system and the future of mobile communications developments .