School of Computer Science and TechnologyTian Jin University

School of Computer Science and Technology，Tian. Jin University （James A. Senn’s Information Technology, 3 rd Edition） Chapter 8 Enterprise and Personal Communications Networks 企业与个人通信网络 Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

第一部分 通信基础 Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

Principles of Communications Networks Definition (Continued) • 通信：借助电信号（含光信号）实现的消息的传递 – Communication: The sending and receiving of data and information over a communications network. • 通信系统：实现消息传递所需的全部技术设备和传 输媒介的总和称为通信系统 Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

Principles of Communications Networks Definition (Continued) • 通信方式（按照通信终端的数量分） – 点对点通信 – 一点到多点 – 多点到多点 Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

Principles of Communications Networks Definition (Continued) • 通信网络 – Communications Network: A set of locations, or nodes, consisting of hardware, programs, and information linked together as a system that transmits and receives data and information. Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

理解“信道带宽”： 2. 信号的失真 Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

理解“信道带宽”： 3. 带宽对传输的影响 Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

调制与解调 数字信号调制 • 调制方式 – 振幅键控 amplitude shift keying, ASK – 移频键控 frequency shift keying, FSK – 移相键控 phase shift keying, PSK • 最常见的应用：借助于调制解调器利用公用电话线 路上网 Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

调制与解调 数字信号调制 Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

模拟数据数字化 (续) Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

数字信号——模拟传输 Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

模拟数据——模拟传输 • 有线电视网络 Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

模拟信号——数字传输 • 数字电话 返回 Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

多路复用 • 信号间分割信道的方式 – 频分多路复用：模拟通信 （Frequency Division Multiplexing Access, FDMA） – 时分多路复用：数字通信 （Time Division Multiplexing Access, TDMA） – 波分多路复用 （Wavelength Division Multiplexing Access, WDMA） – 码分多路复用 （Coding Division Multiplexing Access, CDMA ） Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

TDMA • 时分复用可能会造成线路资源的浪费 Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

TDMA • 统计时分复用 Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

TDMA Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

TDMA Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

TDMA Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

CDMA Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

CDMA Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

CDMA Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

CDMA Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall

Senn, Information Technology, 3 rd Edition © 2004 Pearson Prentice Hall