【作者】 史凡；

【导师】 刘乃安；

【作者基本信息】 西安电子科技大学 ， 通信与信息系统， 2005， 硕士

【摘要】 目前，无线局域网(WLAN)已经得到了比较广泛的应用。为满足人们对随时随地高速无线数据接入的需求，无线局域网应该从网络组成和对移动性的支持上作进一步的发展。 本文主要研究无线局域网在支持快速移动方面的相关技术。因为铁路交通系统具有移动的速度高、范围大、路线固定等特点，这对研究支持快速移动的无线局域网有着网络结构简单、网络环境相对稳定的好处。本文根据这些特点，首先研究了采用无线网状网拓扑结构建立快速移动无线局域网网络的方法，同时研究了用于建立大规模无线局域网的网络规划方法。根据支持快速移动的无线局域网的网络结构，引出了支持快速移动的无线局域网中的物理层传输技术和快速越区切换技术。在物理层技术中主要研究了快速移动无线环境的MIMO-OFDM系统的信道估计算法，建立了STTC-OFDM和SFBC-OFDM两种MIMO-OFDM系统的信道估计模型，分析了MIMO-OFDM中的基于导频的MMSE信道估计算法，利用该算法对系统适应频率选择时变信道的性能进行了详细的分析，并根据仿真结果得出了有用的结论，对支持快速移动的无线局域网物理层的开发有指导作用。在文章最后概要的介绍了无线局域网在快速移动无线环境中的快速切换方法。更多还原

【Abstract】 At present, Wireless Local Area Networks (WLAN) is widely used. To meet the demand on wideband wireless data accessing whenever and wherever, new kind of WLAN should be developed by researching in the aspect of network structure and enhancing the capability of supporting-mobile.In this paper, the main research is on the technologies of supporting-fast-move WLAN。 In the railway system there are the characteristics of moving fast, wide scope, stead track, which provide the convenience for researching on the supporting-fast-move WLAN with the simple network structure and the relative steady environment. Wireless mesh network topology and network planning are used to design the network structure of the new WLAN system. With the new WLAN network structure, the technology of physical layer is deeply researched. In the environment of time variety channel, the channel estimation of MIMO-OFDM system is been researched as the physical layer technology. Two kinds of model of MIMO-OFDM system are been developed, STTC-OFDM and SFBC-OFDM. The pilot based MMSE algorithm of MIMO-OFDM is deeply researched and detailed analyzed. With the result of system simulation, useful conclusion is gotten, which could take a directive effect on the new WLAN development. In the last part of this paper, the fast handoff technology in the new WLAN system is briefly analyzed.更多还原