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HUBEI NORMAL UNIVERSITY
计算机科学与技术学院 College of Computer Science and Technolo
课 题 t接线器的时隙交换仿真 专 业 通信工程 班 级 1203 班 姓 名 张 豪 学 号 2012115020330
目录
第1章 绪论 ··································································································· 1
1.1 交换机 ··································································································· 1
1.1.1交换的诞生····················································································· 1 1.1.2交换机的发展与分类 ········································································ 1 1.1.3交换机的组成 ················································································· 1 1.1.4程控数字交换机的功能 ····································································· 2 1.1.5程控数字交换机的基本原理 ······························································· 2 1.1.6程控交换机的优越性与技术发展 ························································· 2 1.2 MATLAB简介 ························································································· 3 1.3 C语言简介 ······························································································ 4 第2章 接线器 ································································································ 5
2.1 空间接线器 ····························································································· 5
2.1.1空间接线器的组成结构 ····································································· 5 2.1.2 空间接线器的工作方式 ····································································· 5 2.2 时间接线器 ····························································································· 6
2.2.1时间接线器的组成结构 ····································································· 6 2.2.2时间接线器的工作方式 ····································································· 7
第3章 T接线器时隙交换原理的MATLAB仿真和C语言编程实现 ······························ 10
3.1 T接线器时隙交换原理的MATLAB仿真 ······················································· 10
3.1.1 MATLAB仿真程序设计流程如下 ·························································· 10 3.1.2 MATLAB仿真程序 ············································································ 10 3.1.3仿真结果 ······················································································· 11 3.1.4仿真结果分析 ················································································ 13 3.2 T接线器时隙交换原理的C语言实现 ··························································· 13
3.2.1 C语言程序设计流程 ······································································· 14 3.2.2 C语言程序设计 ············································································· 14 3.2.3 运行结果 ······················································································ 15 3.2.4运行结果分析 ················································································ 16 3.3 两种实现方式的比较 ················································································ 16 第4章 总结 ··································································································· 17 参考文献 ········································································································· 18
第1章 绪论
1.1 交换机
1.1.1交换的诞生
1978年，美国人阿尔蒙.B.史端乔提出了交换的构想，其基本思想是将多个终端与一个转接设备相连，当任何两个终端要传递信息时，该转接设备就把这两个用户的有关电路接通，通信完毕再把相应的电路断开。我们称这个转接设备为交换机。交换机的出现不仅降低了线路投资，而且提高了传输线路的利用率。
1.1.2交换机的发展与分类
交换机的发展通常是由于交换技术或控制器的技术的发展而引起的。早期的交换设备有人工交换机、步进制交换机、纵横制交换机、空分式模拟程控交换机等，目前先进的交换机有时分式数字程控交换机、ATM交换机等。
按交换机的使用对象，电话交换机可分为局用交换机和用户交换机；按呼叫接续方式，可分为人工接续交换机和自动接续交换机；按所交换的信号特征，可分为模拟信号交换机和数字信号交换机；按接线器的工作方式，可分为空分交换机（接线器采用空间开关方式）和时分交换机（接线器采用时间开关方式）；按控制器电路的结构，可分为集中控制、分级控制和全分散控制。
1.1.3交换机的组成
一台程控数字交换机主要由交换网络、处理机控制系统和接口电路三部分组成。
图1.1 交换机组成结构框图
（1）交换网络
交换网络可看成是一个有M条入线和N条出线的网络。其基本功能是根据需要是某一入线与某一出线连通，提供用户接口之间的连接。此连接可以是物理的，也可以是逻辑的。物理连接指通信过程中，不论用户有无信息传送，交换网络始终按预先分配方法，保持其专用的接续通路；而逻辑连接即虚连接，只有在用户有信息传送时，才按需分配提供接续通路。
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（2）接口电路
接口电路分为用户接口电路和中继接口电路，其作用是把来自用户线或中继线的消息转换成交换设备可以处理的信号。 （3）控制系统
控制系统是程控数字交换机工作的指挥中心，它由处理机、存储器、I/O接口等部件组成。控制系统的功能通常分为三级。第一级为外围设备控制级，主要对靠近交换网络侧的端口电路及交换机的其他外围设备进行控制，跟踪监视终端用户、中继线的呼叫占用情况，向外围设备送出控制信息。第二级为呼叫处理控制级，主要对由第一级控制级送来的输入信息进行分析和处理，并控制交换机完成链路的建立或复原。第二级的控制部分有较强的智能性，所以这一级称为存储程交换系统的各个部分进行状态检测或试验，诊断各种可能出现的故障，并及时报告输出序控制。第三级为维护测试控制级，用于系统的操作维护和测试，定期自动地对异常情况信息。控制系统三级功能的划分可以是“虚拟”的内在分工，仅说明逻辑控制关系；也可以是“实际”的物理分工，即分别设置专用或通用的处理机来完成不同的功能。
1.1.4程控数字交换机的功能
程控数字交换机的功能分为交换机业务功能和用户功能两类。 （1） 交换机业务功能
控制功能、交换功能、接口功能、信令功能、公共服务功能、运行管理功能、维护诊断功能及计费功能。 （2） 用户功能
程控交换机为用户提供了诸如缩位拨号、热线服务、呼叫转移、禁止呼叫等20多种服务功能。
1.1.5程控数字交换机的基本原理
程控数字交换机的基本原理是一种电路交换原理，主要包括以下三个通信阶段： （1） 电路的建立阶段。通过呼叫信令完成逐个节点的接续，建立起一条端到端的通信电路。 （2） 通信阶段。在已建立的端到端的直通电路上，透明地传送和交换数字化的语音信息。 （3） 电路的拆除阶段。结束一次通信时，拆除电路连接，释放节点和信道资源。
1.1.6程控交换机的优越性与技术发展
与传统的交换机相比，程控数字交换机由于采用了存储程序控制（SPC）技术，不仅大大增强了呼叫处理的能力，增添了许多方便用户的业务，而且显著地提高了网络运行、管理和维护（OAM）的自动化程度。
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