浅析IEEE802.11i标准的改进及运营问题

针对IEEE802.11标准在数据加密和身份认证两方面存在的设计缺陷,IEEE802．11i标准进行了相应改进,较好地解决了存在的问题,但IEEE802．11i在运行中也可能存在一些问题。     

两种无线局域网安全标准WAPI与 IEEE802.11i的比较

本文从两个标准的技术实质与工作原理两方面来加以分析和比较，并在文末预测了它们的前景。     

谈无线局域网的应用

简要介绍了WLAN的定义、特点,讨论了802．11协议族主要内容．重点论述了无线局域网在网络安全方面的发展及应用．通过对无线局域网的应用分析,探讨了它在电信级的运营思路．     

无线局域网安全威胁及802.11i协议关键技术研究

本介绍了当前无线局域网中的安全缺陷以及常见的无线局域网攻击手段，在介绍了无线局域早期802．11i标准安全缺陷的基础上重点分析了刚刚通过的由IEEE制定的802．11i标准中的安全机制和关键技术。     

NEC推出支持IEEE802．11g无线网络的投影机

NEC最新推出支持IEEE802．11g无线网络技术的DLP投影机——LT245 ／LT265 。这两款投影机拥有无线网络投影功能,同时兼容IEEE802．1lb无线网络,机身轻巧便携、画面亮度高。     

无线网络技术在校园网中的应用

随着信息化建设的深入和无线网络技术的发展,无线网络在校园网络建设中的应用越来越广泛．为推动高校信息化资源建设的发展起到了重要作用。本文就无线局域网相关的概念和技术以及在高校内的应用进行探讨.     

无线局域网安全问题及解决方案

本研究了无线局域网常用的安全技术,分析了IEEE802．11b存在的主要安全缺陷,提出了一些解决无线安全问题的方案。     

无线校园网的组建技术与设计

文章分析了无线局域网的基本原理、拓扑结构以及网络设备的选择。阐述了设计无线校园网络的原则、方法和步骤,并结合湖南理工学院的实际情况设计了一个无线校园网络的可行方案。     

浅谈无线局域网在高校图书馆的应用以及安全防范措施

文章简单分析了无线局域网的特点,重点论述了无线局域网是高校图书馆有线局域网中的补充和完善,并提出了无线局域网在图书馆应用时的一些安全策略。     

网络服务质量体系

本文主要描述当前Internet中发展在结构、体系和协议上的服务质量(QoS),在短期的被提议的QoS的标准方法已经开始实施。我们关注网络QoS目前的发展水平,主要是建立在区分服务的原理上。在现实中当我们设法去执行这些结构时会遇到以下几个问题:QoS的问题、提供QoS的网络监控和终端用户接受控制QoS。     

一种基于802.11i的拒绝服务攻击的解决方案

文章分析了802.11i新标准下的无线局域网可能发生的分布式拒绝服务攻击,提出了一种解决方案用来检测并防御这种攻击,并且提出了惩罚不正确行为的矫正措施。在充分考虑了无线局域网中抵御拒绝服务攻击技术上和经济上的困难后,作者提出了一种利用Agent软件的解决方案,能够实现行为监视并且采取适当的措施。     

Performance Improvement of Distributed Coordination Function in IEEE 802.11 Wireless LAN

This paper proposes a modification to distributed coordination function (DCF) to improve the channel utilization in IEEE 802.11 wireless local area networks (WLANs). In the modified DCF, when a station has contended for the channel, it may transmit multiple data frames continuously to the same destination, which is called transmission burst(TB). When the maximum number of data packets transmitted continuously in a TB is set to be 2, the performance is expected to be the best. The theoretical analysis and simulation results show that compared with the standard DCF, the modified DCF can increase the throughput and decrease the delay of the WLAN, and the modification does not introduce any additional control overhead.     

IEEE 802.11协议直扩技术的实现

802.11标准直扩技术主要是对网络的物理层(PH)和媒质访问控制层(MAC)进行了规定,其中对MAC层的规定是重点.同一物理层上可以互操作,逻辑链路控制层(LLC)是一致的,即MAC层以下对网络应用是透明的.这样就使得无线网的"(同网段内)多点接入"和"多网段互连",易于质优价廉地实现.     

Performance analysis of IEEE 802.11 DCF networks

This paper presents an analytical saturation throughput model of IEEE 802.11DCF （distributed coordination function） with basic access in ad hoc mode. The model takes into account freezing of the backofftimer when a station senses busy channel. It is shown that taking into account this feature of DCF is important in modeling saturation throughput by yielding more accurate and realistic results than models known from literature. The proposed analytical model also takes into account the effect of transmission errors. All essential features of the proposed analytical approach are illustrated with numerical results. The presen- tation of the model is proceeded by an overview of approaches to IEEE 802.11 network performance evaluation presented in the literature.     

Mathematical Analysis of Energy Efficiency in IEEE 802.11 DCF

The standardized IEEE ,802. II distributed coordination function （ DCF） provides a contention-based distributed channel access mechanism for mobile stations to share the wireless medium. However, when stations are mobile or portable units, power consumption becomes a primary issue since terminals are usually battery driven. This paper proposes an analytical model that calculates the energy efficiency of both the basic and the RTS/CTS access mechanisms of the IEEE 802. II protocol. The model is validated with simulation results using NS-2 simulation package. The effects of the network size, the average packet length, the initial contention window and maximum backoff stages on the energy efficiency of both access mechanisms are also investigated. Results show that the basic scheme has low energy efficiency at large packet length and large network size, and depends strongly on the number of stations and the backoff procedure parameters. Conversely, the RTS/CTS mechanism provides higher energy efficiency when the network size is large, and is more robust to variations in the backoff procedure parameters.     

IP网络下QoS体系结构

IP网络的QoS技术是当前研究的热点问题,为使IP网络能够提供高质量的服务以满足音频、视频、图像等多种业务要求,应采用合理的分配网络资源的QoS技术。基于IP网络,既能提供保证电信级QoS的业务,同时支持普通互联网业务的网络体系结构,具有良好的网络与业务扩展性。     

On service differentiation in mobile Ad Hoc networks

A network model is proposed to support service differentiation for mobile Ad Hoc networks by combining a fully distributed admission control approach and the DIFS based differentiation mechanism of IEEE802.11. It can provide different kinds of QoS (Quality of Service) for various applications. Admission controllers determine a committed bandwidth based on the reserved bandwidth of flows and the source utilization of networks. Packets are marked when entering into networks by markers according to the committed rate. By the mark in the packet header, intermediate nodes handle the received packets in different manners to provide applications with the QoS corresponding to the pre-negotiated profile. Extensive simulation experiments showed that the proposed mechanism can provide QoS guarantee to assured service traffic and increase the channel utilization of networks.     

On service differentiation in mobile Ad Hoc networks

A network model is proposed to support service differentiation for mobile Ad Hoc networks by combining a fully distributed admission control approach and the DIFS based differentiation mechanism of IEEE802.11. It can provide different kinds of QoS (Quality of Service) for various applications. Admission controllers determine a committed bandwidth based on the reserved bandwidth of flows and the source utilization of networks. Packets are marked when entering into networks by markers according to the committed rate. By the mark in the packet header, intermediate nodes handle the Received packets in different manners to provide applications with the QoS corresponding to the pre-negotiated profile.Extensive simulation experiments showed that the proposed mechanism can provide QoS guarantee to assured service traffic and increase the channel utilization of networks.     

基于QoS的Web服务发现与组合框架

本文提出了一个全面支持QoS的通用Web服务发现与组合框架。该框架将基于QoS的服务发现与组合过程分为接收用户请求、服务发现、功能流程设计、全局QoS服务选择、服务组合执行、组合结果评估6个阶段．能够支持服务组合中功能流程的自动构建和QoS全局最优的Web服务自动选择。     

基于NS2的无线网络传输性能仿真分析

探讨了IEEE 802.11 DCF的特点和NS2的结构、功能和仿真原理.通过NS2对无线网络传榆性能进行仿真测试,并提出了改善无线网络效能异常现象的有效方法.