The first generation of mobile communication (1G) is cellular mobile communication based on analog signal, and it mainly provides voice service.
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 cellular mobile communication systems contained few if any security measures to protect the system operator and users.
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.
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。
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