目 录

2.2 数据通信理论基础 ·····················25

2.2.1 傅立叶分析 ····················25

2.2.2 尼奎斯特定理 ·················25

2.2.3 香农公式 ·······················26

2.3 传输介质 ·································26

2.3.1 有线介质 ·······················27

2.3.2 无线介质 ·······················30

2.4 编码和传输 ······························34

2.4.1 数字-数字编码 ···············34

2.4.2 模拟-数字编码 ···············39

2.4.3 数字-模拟编码 ···············40

2.4.4 模拟-模拟编码 ···············45

2.5 传输技术 ·································45

2.5.1 多路复用技术 ·················46

2.5.2 同步控制技术 ·················49

2.5.3 压缩和压缩方法 ··············52

2.6 交换技术 ·································53

2.6.1 电路交换 ·······················53

2.6.2 存储转发 ·······················54

2.6.3 几种交换方式的比较 ········58

2.7 流量控制技术 ···························58

2.7.1 停等协议 ·······················59

2.7.2 滑动窗口协议 ·················59

2.8 差错控制技术 ···························61

2.8.1 奇偶校验码 ····················62

2.8.2 海明码 ··························63

IV 网络工程师考试辅导

2.8.3 CRC 码 ·························66

2.8.4 差错控制的基本方式 ········68

2.8.5 ARQ ·····························68

2.9 公用网络和租用线路 ··················71

2.9.1 公用网络 ·······················71

2.9.2 租用线路 ·······················71

2.9.3 其他网络 ·······················72

2.10 物理层接口协议 ······················72

2.10.1 RS-232 简介 ··················72

2.10.2 V.35 简介 ·····················73

2.10.3 G.703/G.704 简介 ···········74

2.10.4 USB 简介 ·····················74

2.10.5 1394 接口简介 ···············75

2.11 网络设备 ·······························75

2.11.1 按逻辑功能划分网络设备 ··76

2.11.2 按体系结构划分网络设备 ···76