通信工程专业英语 Lesson 17 The Mobile Telephone System 第17课 移动电话系统 邓 磊 denglei@dgut.edu.cn https://leideng.github.io/communication-english/ (Some pictures are from the Internet) 东莞理工学院 电子工程与智能化学院 2018.10.23/24

Outline Technical Contents Technical Terms Structures and Sentences 1G: Analog Voice 第一代移动电话：模拟话音 2G: Digital Voice 第二代移动电话：数字话音 3G: Digital Voice and Data 第三代移动电话：数字话音和数据 Technical Terms Structures and Sentences

The Evolution of Mobile Communication System

The Evolution of Mobile Communication System

1G: Analog Voice 第一代移动电话：模拟话音 Source: Qualcomm

2G: Digital Voice 第二代移动电话：数字话音

3G: Digital Voice and Data 第三代移动电话：数字话音和数据 Source: Qualcomm

Technique Terms overload n. 过载 microcell n. 微蜂窝 handoff n. （越区）切换 base station 基站 handoff n. （越区）切换 identify vt. 识别 identification n. 鉴定，识别 identity n. 身份 encrypt vt. 加密 encryption n. 加密 decrypt vt. 解密 decryption n. 解密 cryptography [krɪp‘tɒgrəfɪ] n. 密码学 route vt. &n. 按某条路径传输，路线 multimedia n. & adj. 多媒体，多媒体的 packet-switch network 分组交换网 circuit-switch network 电路交换网 channel assignment 信道分配 time slot 时隙

Technique Terms MSC abbr. Mobile Switching Center 移动电话交换中心 MTSO abbr. Mobile Telephone Switching Center 移动电话交换局 PSTN abbr. Public Switched Telephone Network 公共交换电话网 FDD abbr. Frequency Division Duplex 频分双工 TDD abbr. Time Division Duple 时分双工 GSM abbr. Global System for Mobile communications 全球移动通话系统 CDMA abbr. Code Division Multiple Access 码分多址 SIM abbr. Subscriber Identity Module 用户身份模块 BSC abbr. Base Station Controller 基站控制器 SMS abbr. Short Message Service 短信业务

Structures and Sentences The key idea that gives cellular systems far more capacity is the use of relatively small cells and the reuse of transmission frequencies in nearby (but not adjacent) cells. 使蜂窝系统具有很大容量的关键在于使用了相对较小的蜂窝小区和在附近（但不是临近的）小区间应用频谱复用。

Structures and Sentences Notice that for each frequency set, there is a buffer about two cells wide where that frequency is not reused, providing for good separation and low interference. 需要注意的是：为了实现效果良好的隔离和低干扰，每组频率存在约两个小区的缓冲带。在这些缓冲带中，频率不被复用。

Structures and Sentences In an area where the number of users has grown to the point that the system is overloaded, the power can be reduced and the overloaded cells split into smaller microcells to permit more frequency reuse, as shown in Figure 17.1(b). 在一个地区，如果用户数量太大以致系统过载，我们就可以通过减少传输功率并将过载小区分为更小的微蜂窝小区来实现更高的频率复用（见图17.1(b)）。

Structures and Sentences When it was first proposed for cellular systems, the industry gave it approximately the same reaction that Columbus first got from Queen Isabella when he proposed reaching India by sailing in the wrong direction. 当CDMA最初被提出用于蜂窝系统时，工业界对此的反应几乎就像伊丽莎白女王听到哥伦布提出走错误的航向到达印度一样。

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