STM-1信号中63个2Mbi/s的互通

介绍了SDH的STM—1信号中的TU-12支路信号时隙安排,以便读者对不同厂家的设备是否符合ITU-T建议有所了解。     

交换机局间155Mbit/s接口在北京网的使用

1 问题的提出1999年在讨论北京电信本地网汇接交换机扩容方案时,我们看到,由于交换机的集成度越来越高,汇接局容量越来越大(当时一个汇接局准备安装8万线),使得2 Mbit/S电缆更加拥塞.由于各汇接局机房(交换机房和传输机房)面积紧张,无论是交换机房还是传输机房,2 Mbit/S电缆占用空间较大.以一个汇接局安装8万线为例,如果按照2 670个2Mbit/S计算,交换机房至传输室DDF的电缆,因不同厂商的电缆程式各异、条数不同,以最多电缆条     

STM-1中2 Mbit/s信号的解映射及去同步

论述了ＳＴＭ－１的解映射及去同步以获得Ｗｂｉｔ／ｓ异步信号的实现方案,并提出了减小指针调整引起的抖动的自适应比特泄漏率算法,ＦＰＧＡ、ＡＳＩＣ实现的硬件电路测试结果证明,文中论述的实现方法其性能完全满足ＩＴＵ标准。     

利用光纤数字同步传送网2.048 Mbit/s支路传送高精度标准时间信号

首次提出一种利用光同步数字传送网的2.048Mbit/s信号传送高精度时间编码信号的方法和实验结果。它可以使整个通信网的交换机、计费系统、网管系统、基站控制器等设备实现与UTC的时间同步。目前的实验证明,时间同步的不确定度优于±5μs。     

交换机采用155Mbit/s中继对通信网络带来的影响

1 前言在当今通信领域激烈竞争的时代,各通信运营商面临着严峻的挑战.为了在竞争中立于不败之地,必须不断地改进自己的网络,使其具有灵活快速提供业务的能力,同时要不断降低网络运营维护管理的成本.简化网络结构,使其易于扩展、易于网络话务规划、最大限度的利用网络资源是降低网络运营成本的重要途径,是电信运营商非常关注的问题.     

同步数字体系中155Mbit/s净荷的误码测试

本文基于光纤传输同步数字体系(S D H)系统的开发背景,较为详细地总结了155Mbit/s速率下的净荷误码测试机理.最后给出了净荷的误码测试方法以及误码测试系统的信号流程.     

SONET／SDH155Mbit／s分插复用器中光群路单元板的参考设计

分插复用器（ＡＤＭ）是组成同步数字传输网（ＳＤＨ／ＳＯＮＥＴ网）的基本单元,它可以同ＳＤＨ的终端复用器（ＴＭ）、同步数字交叉连接设备（ＳＤＸＣ）及网络管理设备（ＴＭＮ）等网络单元（ＮＥ）一起组成配置灵活的ＳＤＨ传输网络。光群路单元板（ＯＡＵ板）是ＡＤＭ的核心部分。本文简要介绍ＡＤＭ的功能组成与ＯＡＵ板的参考设计。     

一种用于SDH 2Mbit/s支路输出口的全数字锁相环

在本文中我们提出了一种具有极低通带宽度的二阶全数字锁相环，并采用了一些非线性的改进措施，使其具有一个相对较宽的牵出范围，从而可以用来恢复Ｅ１支路信号的时钟。经硬件实验证实，完全可以满足ＩＴＵ－Ｔ对抖动抑制特性的要求。由于数字集成电路技术成熟，集成度远远高于模拟集成电路，因而采用全数字锁相环对系统的集成有明显的益处。     

Time slot assignment in a heterogeneous environment of a SS/TDMA system

In this paper we consider the time slot assignment for a heterogeneous environment in which circuit-switched traffic and packet-switched traffic share the same satellite. In constructing a single time division multiple access (TDMA) frame for both traffic types, their different characteristics must be taken into account. This problem is known to be NP-complete and a couple of heuristic partial optimization algorithms have been developed. In this paper, we first provide a theoretical result to improve the existing partial optimization algorithms; then a fully optimizing heuristic algorithm is presented. Simulation results show that our algorithm provides a much better solution quality than existing ones. © 1997 John Wiley & Sons, Ltd.     

关于TD-LTE网络物理层峰值吞吐率的分析

本文主要着重探讨了TD-LTE网络小区和和终端物理层理论上的峰值吞吐率,分析了上下行不同时隙配比下是否与TD-SCDMA共存系统等不同情况的区别,最后给出相应的理论物理层峰值吞吐率,可供TD-LTE网络规划参考。     

基于MPC8260的双100Mbit/s快速以太网的VxWorks驱动实现

介绍了基于MPC8260的FCC(快速通信控制器)实现双100Mbit/s快速以太网的简要原理,并结合ATM(异步传输模式)综合交换系统的工程实现,介绍了硬件配置过程.在基于VxWorks嵌入式操作系统的BSP(板级支持包)的编写中,叙述了100Mbit/s以太网驱动的实现流程,并简要给出了应用程序的调用入口方法.     

A co-designed coding,modulation and equalization scheme for the transmission of 155-52 Mbit/s data over a 72 MHz intelsat transponder. Part 1: Coding and modulation performance

This paper reports on the application of co-designed coding, modulation and equalization techniques to an INTELSAT requirement for transmitting 155-52 Mbit/s data over a 72 MHz satellite channel. A specific solution as regards coding, modulation and equalization is proposed and analysed that differs from ‘standard’ concatenation in that the inner decoder integrates equalization, modulation and coding. In Part 1 results of extensive computer simulations are presented, examining the effect of adjacent channel interference, co-channel interference, non-linear distortion in representative ground and space TWTAs, multiplexers and filter distortion. In Part 2 a novel technique for integrating decision feedback equalization into the inner decoder is described. The gains in integrating the coding and equalization are shown to be significant for channels that need equalizing.     

矢量网络分析仪的时域功能在天线测量中的应用

介绍了利用矢量网络分析仪的时域功能测量天线系统驻波系数、增益和方向图的方法.这种方法通过确定各反射点的位置和反射大小,以及在天线增益和方向图的测量中去掉周围环境的反射影响,使测量的结果更精确.     

A Neural Network Approach to Blind Estimation of PN Spreading Sequence in DS/SS Signals

As the power spectrum density of direct sequence spread spectrum (DS/SS or DS), signals is often much lower than the noises’, the DS signals have the ability to resist interception and interference. But in point of fact, if we have get some parameters of the DS signals, including information symbol period, chip period of the pseudo noise (PN) sequence, we can estimate the PN sequence in DS signals blindly, this has great value for management or interception of DS communications. Ref.[1…