摘要与有线局域网相比,无线局域网(Wireless Local Area Networks，WLAN) 以无线多址信道作为传输媒介，提供传统有线局域网(Local Area Network，LAN)的功能，并摆脱线缆的缺点，可以随时随地接入Internet。具有灵活性强、安装简单、部署成本较低、扩展能力好等优点,受到了广泛的应用。
随着IEEE802.11无线局域网迅猛发展，其自身存在的一些问题如:远近效应，隐藏终端问题，捕获效应等也逐渐受到关注，而解决这些问题的媒体访问控制技术是影响无线局域网性能的关键，因此对无线MAC层研究也日益增多。IEEE 802.11是目前广泛应用于WLAN的协议标准,主要用于解决有限的信道资源在多用户间进行分配的问题，通过有效的共享介质访问机制，提高资源的使用率和系统的性能。本论文针对 IEEE802.11DCF协议进行研究，着重对吞吐量进行了分析讨论。本文对bianchi提出的饱和吞吐量条件下的Markov模型进行比较了分析,比较协议在不同基站数及数据帧长条件下基本访问模式和RTS/CTS访问模式性能的差异。最后对协议进行改进，在考虑了竞争窗口的动态调节,改进了算法减少了系统碰撞,加强了系统吞吐量。9226
关键词:802.11b;DCF;二文马尔可夫链模型;吞吐量;NS2
毕业设计说明书（论文）外文摘要
Title The Performance Analysis Of IEEE 802.11 Protocol
Abstract
Compared with Local Area Networks(LAN),the Wireless Local Area Networks(WLAN) uses wireless multiple access channel as transmission medium to provide the function of LAN. In addition,the WLAN avoids the deficiency of cable and can access the Internet whenever and wherever possible.As for its strong flexibility, simple installation, low cost and expansion capability,it has been widely applied in the life.
With the rapid development of IEEE802.11 wireless local area network, it also exits some problems such as the near-far effect, hidden terminal problem and capture effect .These problems also attract more and more attention, and the solution to them is the key influencing the performance of the WLAN.The research on the media access control(technology(MAC) of wireless LAN is increasing.IEEE 802.11 is a standard protocol now widely used in the WLAN, which is mainly used to solve problem of the limited channel resource distribution between multiple users .It improves the utilization rate of resources and the performance of the system through effective shared medium access mechanism. The paper is based on the IEEE802.11DCF protocol research, focusing on the analyzation and discussion of the throughput. This paper analyses the saturation throughput on the Markov model which is reprensented by Bianchi. It compares performance difference of protocols in different base station number and data frame length under the condition of basic access mode and RTS/CTS mode. Taking the dynamic competition window adjustment into consideration,the paper adjusts the algorithm to improve the protocol,which has the enhancing system throughput and reduced system crashes.
Key words:802.11b; DCF; two-dimensional Markov chain model; throughput; NS2
目 次
1 绪论 1
1.1 WLAN的拓扑结构 1
1.1.1 点对点模式 1
1.1.2 基础架构模式 1
1.1.3 多AP模式 2
1.1.4 无线网桥模式 2
1.1.5 无线中继器模式 3
1.2 IEEE802.11系列标准概述 3
1.2.1 几种常见的 IEEE802.11标准 4
1.2.2 IEEE802.11协议体系结构 5
1.3 本论文的章节安排 6
2 无线局域网MAC协议简介 6
2.1 IEEE 802.11 MAC中的主要技术 6 IEEE协议性能分析+文献综述:http://www.youerw.com/tongxin/lunwen_7866.html