CDMA2000信号的实时捕获及分析

随着第三代移动通信(3G)技术的发展,如何开设3G实验项目是本课程面临的一大问题。3G设备相对十分昂贵,又存在WCDMA、CDMA2000、TD-SCDMA 3种不同的标准,全面开设实验存在不少困难。利用已购买的大型仪器完成对CDMA2000信号的实时捕获及分析,给出了实验步骤、指标测试与相关分析。     

3G基站3KW风光发电互补型独立供电系统的设计

研究3G基站3KW风光发电互补型独立供电系统的结构设计与控制系统,系统基站备用储蓄电源,以充分保证基站在任何情况下都能正常供电。在不同天气状态下,实现风力发电和太阳能发电系互补。通过对不同天气和负载下的系统仿真实验,验证了3KW风光发电互补型独立供电系统的有效性。     

W-CDMA系统中的Turbo Code仿真

在第三代移动通信系统W CDMA和CDMA2 0 0 0中 ,turbocode在高速数据传输业务方面已倍受青睐 .本文给出了turbocode在瑞利衰落信道和加性高斯白噪信道下的性能仿真结果 ,并在各种不同条件下与卷积码的性能进行了比较 .得到了较为可信的仿真结果 .     

新一代移动通信系统--CDMA

本文介绍了新一代移动通信系统的主要技术CDMA(Code Divitior Multigl Acces)技术,提出了CDMA系统中的关键术语,并对其优势作了简要的介绍.     

“新生代农民工”犯罪问题及对策研究

新生代农民工是因当前中国经济社会高速发展和城乡二元社会结构长期存在而形成的一个特殊群体。和第一代农民工相比,"新生代农民工"具有诸多特征,其中最突出的一点是他们希望成为城市的正式成员,但社会却还没有做好接受他们的准备。在这种情况下,部分"新生代农民工"犯罪,主要在于社会的不公正、相对剥夺感的产生以及社会性歧视等。预防和控制"新生代农民工"犯罪,应在充分认识"新生代农民工"的群体特征、社会地位、犯罪原因的基础上,从铲除诱发其犯罪的根源和土壤着手。     

Learning to Teach Through Teaching and Being Taught

Teacher shortage has been a problem in northern Norway for decades. The authorities have taken steps to stimulate the supply of teachers in these regions through economic incentives and decentralized or part‐time teacher education. The full effect of these measures cannot be fully evaluated till the early or middle 1990s. In this article, structure and assessments of first and second generation decentralized and part‐time teacher education are referred. Even though this approach to teacher education has been disputed, it now seems to be accepted by most interest groups. The main problems of these programs seem to be related to the pressures on students trying to fill multiple roles (student, part‐time teacher, mother), and the supervision of students.     

Evolution to 3G mobile communication

For the last couple of years, one of the hottest topics in computing and communications has been wireless technology. During this time, the technology has attracted many users and has undergone numerous changes, including Internet connectivity. It appears that wireless technology has reached a turning point, as vendors and researchers prepare to take it to the next level. A key issue for wireless is what form the technology’s next generation will take. The selection of the ‘air interface’ for a wireless system is a seminal decision for a service provider. The air interfaces and an overview of data transfer in cellular networks for first generation (IG) analog systems, second generation (2G) digital systems, enhanced second-generation (2.5G) systems, and third generation (3G) advanced digital cellular systems are discussed in this article. The emphasis is on covering the key characteristics of each air interface technology.     

数控车床编程加工技术及典型实例分析

利用数控车床进行零件的加工,要根据零件的复杂程度确定是手工编程还是自动编程,手工编程是自动编程的基础。以FANUC系统手工编程为例,从零件图纸分析,确定加工方案,数值计算,根据编程规则,主要是利用复合循环指令G71、G72、G76、G70进行编程,使用复合循环指令编程,可以大大简化程序编制,加工出符合技术要求的零件。     

第三代移动通信中的一种新型AFC算法

在无线移动通信中 ,接收机的本地振荡频率和载波频率之间往往存在较大的频率偏差 ,AFC用于克服此频偏 .传统的AFC采用了模拟环路滤波器 ,因此只能工作在连续的输入信号模式 ,而不能工作于间断导频的W CDMA系统中 .本文对此提出了新的AFC算法 :用最大似然方法估计衰落信道 ,得到间断导频信道的幅度和相位 ,并在一个时隙中进行最大比合并 ,从而得到一个判决变量 .最后用这些变量调节本地振荡频率 ,以跟踪载波频率 .仿真结果显示这种新的AFC算法是可靠而有效的 .     

CDMA2000的体系演进及其关键技术

本文首先介绍了从IS-95到CDMA2000的体系演进过程和CDMA2000IX的技术优势，然后讨论了其扩展版本CDMA20001XEV的基本要求、技术特点和关键技术，最后分析了其发展前景。     

利用CDMA技术原理求解一套试题

笔者在讲授网络工程专业主干课《计算机网络》时,碰到过一道试题,起初无从下手,学习CD-MA技术后找到了答案。通过这道试题,旨在介绍介于第二代和第三代移动通信技术之间的CDMA概念的同时,重在推广应用其基本原理。     

CDMA扩频通信中m序列与Gold序列的比较及应用

m序列和Gold序列是CDMA扩频通信中两种常用的伪随机序列.就这两种序列的性质、生成原理进行了详细的分析研究,然后用表格及Matlab仿真的结果将这两种序列的主要性能进行了比较,最后在比较的基础上分析了它们在CDMA扩频通信中的典型应用.     

CDMA技术在数据通信系统中的应用

人类对更高质量无线通信的需求推动了CDMA技术的出现．CDMA是按照码型结构的差别来分割信号的．在CDMA系统中，用户数的增加相当于背景噪声的增加．在保持高质量通话的同时，CDMA可以容纳更多的用户，CDMA手机的用户每次通话时，系统编码有4．4万亿种可能的排列，具有天然的保密性，其消息在空中信道上被截获的概率几乎为零．CDMA技术的标准化，推进了这项技术在世界范围内的应用．     

Parental Socioeconomic Status,Communication, and Children's Vocabulary Development: A Third‐Generation Test of the Family Investment Model

This third‐generation, longitudinal study evaluated a family investment perspective on family socioeconomic status (SES), parental investments in children, and child development. The theoretical framework was tested for first‐generation parents (G1), their children (G2), and the children of the second generation (G3). G1 SES was expected to predict clear and responsive parental communication. Parental investments were expected to predict educational attainment and parenting for G2 and vocabulary development for G3. For the 139 families in the study, data were collected when G2 were adolescents and early adults and their oldest biological child (G3) was 3–4 years of age. The results demonstrate the importance of SES and parental investments for the development of children and adolescents across multiple generations.     

一种光纤CDMA系统的双极码编解码方案

提出一种光纤ＣＤＭＡ系统的双极码编解码方案．该方案综合利用光波分复用ＷＤＭ与现有的光纤ＣＤＭＡ技术,把已经较为成熟的射频ＣＤＭＡ的双极码编码技术移植到光纤ＣＤＭＡ系统中,以达到改善光纤ＣＤＭＡ地址码相关性能的目的     

The story of large electron positron collider

In this first part of the article on LEP detector, we have described in brief the standard model for the fundamental constituents of matter. We have also described the experimental supports for the electroweak theory and quantum chromodynamics, which are the two pillars of the standard model. In the next part of the article, we will focus on the LEP detector and the measurements that have been carried out with it.     

基于电力系统仿真软件的光伏发电系统建模

通过对光伏发电系统光伏电池的原理分析,得出光伏电池的数学理论模型,进而搭建光伏发电系统的光伏电池等效模块,再经过直流-直流变换模块、逆变桥变换环节、滤波环节,得到完整的光伏发电并网系统模型.利用PSCAD软件建立了光伏发电的模型,完成了光伏发电各环节的搭建和调试.该模型可以定量地分析在外部输入参量,如外部光照量、电池板温度等变化时,光伏系统的输出电压、输出功率、输出波形的变化情况以及并网后对于系统网络的影响.作为一个等值电源,还可以计算出光伏发电系统并网的等值阻抗.     

THE TRANSNATIONALIZATION OF SOCIAL AND CULTURAL LIFE THROUGH MIGRATION: IS THERE AN IMPACT ON HIGHER EDUCATION?

In an increasingly interdependent and inter‐linked world, the phenomenon of migration takes on added importance. It has existed in Europe for many years even if in recent times the immigrants have come from outside Europe rather than from southern European to northern European countries. Economic problems have stimulated increased xenophobia on the part of host societies while at the same time, the children of the first generation of immigrants have faced challenges and have promoted the cultural enrichment that comes from bi‐culturalism. Multi‐culturalism is well worth studying and promoting for it represents a cultural enrichment for Europeans leading to a new cultural synthesis for the continent. Both schools and higher education institutions must take up the challenge of multi‐cultural education which should be more than a superficial dose of folklore, dancing, and exotic food. The children of the second generation of immigrants have frequently studied their home cultures and languages in their university courses, this in order to better understand themselves and their relationship to their two cultures. In their active lives, these graduates will further enrich European culture by helping to elaborate a new cultural synthesis.     

CDMA直放站隔离度自适应检测方法

直放站的使用虽然有很多优点怛是当收发天线隔离度不够时会出现自激现象,对网络造成严重影响。因此本文主要实现对CDMA直放站收发天线之间隔离度检测功能。当CDMA直放站天线隔离度低干直放站正常工作所要求时,检测出当前实际天线隔离度大小,并根据当前实际天线隔离度大小提出了自适应的隔离度检测算法,消除CDMA直放站自激现象,提高系统性能。     

一种新的并行干扰消除Rake系统

为了消除DS CDMA系统中的多径干扰,本文提出了一种新的采用并行干扰消除算法的Rake系统:数据符号的假设检验值通过线性判决获得,根据假设检验值和其它已知用户信息估计多径干扰,然后进一步分析了该系统在Rayleigh衰落信道下的性能并与传统的并行干扰消除算法、传统的Rake接收机进行了比较.结果表明:该系统不仅可大大改进传统Rake接收机性能,且结构简单、易于实现.