无线局域网在电力系统中的应用方案设计

简单介绍了无线局域网技术及其发展情况，给出了电力系统中的典型应用方案。以无线局域网技术为依托，结合最新的网络技术、VOIP语音技术及接口转换技术，可以提供一套全新的变电站、供电所通信通道整体解决方案，满足电力系统的话音、数据、图像及计算机联网的需求。     

无线局域网标准与应用

随着无线局域网技术的不断发展，无线局域网的应用与日益广泛。介绍了无线局域网的基本概念和特点，分析了无线局域网的相关标准，并对无线局域网技术的应用前景做了展望。     

无线局域网QoS技术发展研究

无线局域网由于技术简单、成本低廉并能提供高速率的数据传输而得到广泛的应用，然而已经发布的IEEE 802．11协议并没有内建对QoS的支持。介绍了无线局域网QoS技术的发展，包括针对IEEE 802．11MAC层协议进行的各种QoS增强技术，以及即将发布的IEEE 802．11e标准对QoS的支持。     

高速无线局域网主要技术

以IEEE802．11标准为基础的无线技术已经成为目前无线局域网（WLAN）技术的主流。通过接入无线网络实现移动办公已经成为很多人生活方式的一部分。为了满足人们对传输速率日益增长的要求，在相继推出了802．11b、802．11a以及802．11g标准以后，IEEE工作组即将提出下一代高速无线局域网标准——802．11n。     

无线局域网标准 IEEE802.11g的技术优势

本文详细介绍了无线局域网标准IEEE802.11g的发展历程及其技术优势。     

无线局域网标准与应用

本文首先介绍了无线局域网的概念及标准ＩＥＥＥ８０２１１,并详细说明了无线局域网的特点及应用范围,最后通过实际工程案例说明无线局域网的组网方式。     

基于IEEE802．11的无线局域网技术及其应用

本文介绍了IEEE802．11无线局域网的概念与标准、协议体系和组网模式，进一步探讨了无线局域网的应用。     

无线局域网技术探讨

无线局域网成为计算机网络的一个重要组成部分,采用什么的技术标准显得很重要,本文探讨了几种技术标准,包括80．211系列,蓝牙技术和我国的WAPI技术,并分析了安全性。     

无线局域网在移动机器人远程控制中的应用

介绍了无线局域网技术的发展、特点，并详细介绍了IEEE802．11b无线局域网标准，在此基础上以ActivMedia Robotics公司的P3一DX型移动机器人为对象，构建了一种基于无线局域网的移动机器人远程控制系统应用方案，开发了基于服务器／客户模式的控制平台。     

无线局域网的安全机制探讨

本文分析了无线局域网的五种安全机制的原理及特点，在此基础上，提出了它们各自的优、缺点及适用范围．     

基于IEEE 802.11n无线局域网系统的符号同步

IEEE 802.11n无线局域网标准为了避免不必要的波束成型采用了循环移位机制,该机制对符号同步造成障碍,使得符号同步产生所谓的假多径问题。针对这个问题,本文提出了一种采用移位叠加的本地训练序列互相关的同步方法。通过对IEEE 802.11n无线局域网系统进行建模仿真,对新提出的方法和前人所提出的方法进行比较。最终验证该同步方法具有实用性,能够大幅度的提升同步的精度,使得符号同步的定位误差控制在2个采样点之内。     

应用于802.11b无线局域网的低噪声高线性度的CMOS射频接收机

实现了一个单片集成、直接转换结构的2.4GHz CMOS接收机. 这个正交接收机作为低成本方案应用于802.11b无线局域网系统,所处理的数据传输率为该系统的最大速率--11Mbps. 基于系统设计以及低噪声高线性度考虑,设计了低噪声放大器、直接转换混频器、增益可变放大器、低通滤波器、直流失调抵消电路及其他辅助电路. 该芯片采用中芯国际0.18μm 1p6m RF CMOS工艺流片,所测的接收机性能如下：噪声系数为4.1dB,高增益设置下低噪声放大器与混频器的输入三阶交调点为-7.5dBm,整个接收机的输入三阶交调点为-14dBm,相邻信道干扰抑制能力在距中心频率30MHz处达到53dBc,输出直流失调电压小于5mV. 该接收机采用1.8V电源电压,I, Q两路消耗的总电流为44mA.     

针对WLAN的特定攻击手段与相关检测技术

文章分析了各种针对无线局域网的攻击手段,并提出了相应的检测机制。针对基于MAC欺骗的攻击手段提出了一种基于802.11帧序列号的异常进行检测的技术,对于其它的无线网络入侵手段等则利用匹配攻击特征的方法,实现入侵检测。     

IEEE802.11无线局域网标准

介绍了IEEE802.11无线局域网技术规范.给出了ISM频段、扩频技术的背景及各国相应的标准、规范.描述了允许可证2.4GHzISM频段的直接序列扩频技术及IEEE802.11协议规范。     

无线局域网IEEE 802.11的安全缺陷分析

文章主要分析了无线局域网（Wireless Local Area Network，WLAN）IEEE802．11的安全机制，从认证和加密的角度讨论了IEEE802．11存在的主要安全问题。给出了Wireless LAN安全机制应具备的安全性质，并提出了改善WLAN安全性的解决方案和安全措施。     

802.11b和蓝牙共存技术的研究

首先介绍了在通信技术迅猛发展的当今时代,将802.11b和蓝牙集成在同一系统上会更加方便人们的日常工作,然后分析了802.11b和蓝牙共存的技术难点,提出了一种实际应用中解决方案。并通过分析得到了这个方案优势,对实际的工程应用具有一定指导意义。     

WLAN802.11n组网规划相关问题研究

802.11n标准的众多可选特性增加了其组网规划的复杂性.本文从802.11n关键技术人手,分析了影响802.11n组网规划中网络覆盖、容量、双流工作模式、信道捆绑等关键问题,并结合实际测试,给出了802.11n实际组网规划中应注意的问题和规划设计建议.     

下一代无线局域网标准802.11ac

802.11ac是新一代无线局域网技术标准,是802.11n标准的延续。在继承了已有WLAN标准中许多先进技术的基础上,802.11ac在物理层和MAC层做了一系列的技术改进,来保证高质量、高传输速率的网络服务。就像以前的每次技术标准的进步一样,802.11ac标准同样有很强的向后兼容能力,能和已有的802.11a/n网络很好的共存,为用户体验网络服务提供更多的选择。     

Throughput Analysis and Admission Control for IEEE 802.11a

We propose a new Markov model for the distributed coordination function (DCF) of IEEE 802.11. The model incorporates carrier sense, non-saturated traffic and SNR, for both basic and RTS/CTS access mechanisms. Analysis of the model shows that the throughput first increases, and then decreases with the number of active stations, suggesting the need for an admission control mechanism.We introduce such a mechanism, which tries to maximize the throughput while maintaining a fair allocation. The maximum achievable throughput is tracked by the mechanism as the number of active stations increases. An extensive performance analysis shows that the mechanism provides significant improvements.Mustafa Ergen received the B.S. degree in electrical engineering from Middle East Technical University (METU) and was the METU Valedictorian in 2000. He received the M.S. and Ph.D. degrees in electrical engineering in 2002 and 2004, the MOT certificate of HAAS Business School in 2003, and the M.A. degree in International and Area Studies in 2004 from the University of California, Berkeley.Dr. Ergen has been conducting research in wireless communication networks with an emphasis on sensor networks, wireless LAN and OFDM systems and is the author of many works in the field, including the book (with A.R.S. Bahai and B.R. Saltzberg) Multi-Carrier Digital Communications: Theory and Applications of OFDM (New York: Springer, 2004).He is National Semiconductor Post Doctoral Fellow and was awarded eight times Bulent Kerim Altay Award by department of electrical engineering in METU and received Best Student Paper Award in IEEE ISCC 2003 and has an invited paper in IEEE GLOBECOM CAMAD 200.Pravin Varaiya is Nortel Networks Distinguished Professor in the Department of Electrical Engineering and Computer Sciences at the University of California, Berkeley. From 1975 to 1992, he was also Professor of Economics at Berkeley. His research is concerned with communication networks, transportation, and hybrid systems. He has taught at MIT and the Federal University of Rio de Janeiro, Varaiya has held a Guggenheim Fellowship and a Miller Research Professorship. He received an Honorary Doctorate from L’Institut National Polytechnique de Toulouse, and the Field Medal of the IEEE Control Systems Society. He is a Fellow of IEEE and a member of the National Academy of Engineering. He is on the editorial board of several journals, including “Discrete Event Dynamical Systems” and “Transportation Research-C.” He has co-authored three books and more than 250 technical papers. The second edition of “High-Performance Communication Networks” (with Jean Walrand) was published by Morgan-Kaufmann in 2000. “Structure and interpretation of signals and systems” (with Edward Lee) was published in 2002 by Addison-Wesley.     

Adaptive Power Saving Mechanisms for DCF in IEEE 802.11

Distributed Coordination Function (DCF) is the basis of IEEE 802.11 MAC sublayer. To improve energy efficiency, IEEE 802.11 has specified power saving mechanism (PSM) for DCF. However, the performance of PSM degrades seriously when load is heavy. In this paper we first analyze the reason of performance degradation, and then propose two adaptive mechanisms: PSM+ and fairPSM+. Numerous simulation results have shown that these two mechanisms can achieve high performance with heavy load and still get the same performance as PSM when load is light.Shihong Zou was born in 1978. He received his Bacchelor of Engineering degree in Computer Engineering from Nanjing University of Posts and Telecommunications (Nanjing, China) in 1999, and his Ph.D. degree in communication and information systems from Beijng University of Posts and Telecommunications (BUPT) in 2004. He is currently a lecturer in BUPT. His research interests include IP QoS, WLAN, mobile ad hoc networks and network security.Haitao Wu was born in 1976. He received his Bachelor of Engineering (B.E.) degree in Communication Engineering from Beijing University of Posts and Telecommunications (BUPT) in 1998, and his Ph.D. degree in communication and information systems from BUPT in 2003. He is currently a Post-doctor in Microsoft Research Asia (MSRA), wireless and networking group. His research interests include IP QoS, TCP/IP, wireless networks and peer-to-peer networks.Shiduan Cheng graduated in communication engineering at the Beijing University of Posts and Telecommunications (BUPT) in 1963. Since then she has been working at BUPT. From 1984 to 1987 and in 1994 she twice joined Alcatel Bell, Belgium as a visiting scholar, where she was involved in R&D work on ISDN and B-ISDN networks and systems. She became vice dean of the computer department of BUPT in 1987. From 1992 to 1999 she was the director of The National Key Laboratory of Switching Technology and Telecommunication Networks of BUPT. In the same duration she was also the head of The Switching and Networking Expert Group in 863 program, a national high-tech R&D plan organized by The Ministry of Science and Technology of China. She has published more than 100 papers and several books in the field of telecommunications. She is currently the vise director of Standing Committee of Science of BUPT. Her research interests cover ISDN, ATM, TCP/IP, switching software, protocol engineering, traffic engineering, network performance, QoS, security and survivability. Currently she is working on QoS control, measurement and management for the next generation Internet.