移动通信基本知识:从通信网的角度看，移动网可以看成是有线通信网的延伸，它由无线和有线两部分组成。无线部分提供用户终端的接入，利用有限的频率资源在空中可靠地传送话音和数据；有线部分完成网络功能，包括交换、用户管理、漫游、鉴权等，构成公众陆地移动通信网PLMN。从陆地移动通信的具体实现形式来分主要有模拟移动通信和数字移动通信这两部种。-Basic knowledge of mobile communications: From the perspective of communication networks, mobile networks can be seen as an extension of wired communication network, which is both wireless and wired components. Part of user terminals to provide wireless access, frequency of use of limited resources in the air and reliable transmission of voice and data　wired part of the completion of network functions, including switching, subscriber management, roaming, authentication and so on, constitute a public land mobile communication network PLMN. From land-based mobile communications to the specific forms of the main points have analog and digital mobile communications that two kinds of mobile communication.