摘要随着城市轨道建设的快速发展和城市无线网的全面建设，城市无线网引入地铁已是发展的必然。由于列车的高速移动，如何保证信息的低延迟、高带宽、安全性地在地铁无线网上使用成为应用探索的焦点。随着我国科技发展，人们对无线通信的需求必不可少，运用手机无线网络通信已经成为生活中的一部分，在我国高速公路和铁路上基本已经覆盖，地铁高铁也在逐步发展中，人们在地铁带来的方便通行时，总是被高速环境下和地下的信号衰弱所困扰，使得乘客在乘车时无法进行数据通信。74059

通过分析研究可知，Wifi是一种无线宽带技术，广泛用于家庭和企业单位，同时人们对Wifi的需求与日俱增。其特点在于传输速率快、覆盖范围广、有效距离长、组网简单并且网络可靠性高。其发展迅速，将Wifi技术引入地铁也是发展的必然，但由于地铁运行时，处于地下以及隧道，并且运行速度快。如何解决Wifi对地铁的覆盖问题，以及信号的传输问题已成为关键。

本设计针对地铁在高速运动下，车体，小区切换以及多普勒频移带来的影响进行了理论分析，并且阐述了地铁中无线通信技术的特点，讨论了地铁的网络覆盖，设计方案以及技术的突破。论文最后提出了光载无线（ROF）技术，采用光纤通信，以配置AP主机进行网络覆盖，利用多种节点技术达到传输速度快，损耗低，安全性高等特点，解决了车体传播损耗高，小区频繁切换带来的问题，为地铁的无线通信技术的发展和未来Wifi-ROF技术的发展提出了建设方案。

该论文有图20幅，表4个，参考文献50篇。

毕业论文关键词：地铁  无线网络  快速  移动

Application of Wifi in Metro

Abstract With the rapid development of urban railway construction and the comprehensive construction of urban wireless network, the introduction of metro is the inevitable development of urban radio network。 Due to the high speed of the train, how to ensure the information of low latency, high bandwidth, security in the subway wireless network to use as the focus of research。 With the development of science and technology of our country, people's demand for wireless communication is essential, using mobile phone wireless network communication has become a part of life, in our country freeway and railroad has basically been covering, the subway high iron also in progressive development, people in the subway will pass, always be plagued by high speed environment and underground signal attenuation, so that passengers on the bus to data communication。 

Through the analysis, we can see that Wifi is a kind of wireless broadband technology, which is widely used in family and business units, while the demand for Wifi is increasing。 The characteristic of the network is characterized by high transmission speed, wide coverage, long effective distance, simple network and high reliability。 Its development into all walks of life, the introduction of Wifi technology into the subway is inevitable, but because of the subway operation, in the underground and tunnel, and running fast。 How to solve the problem of Wifi coverage of the subway, as well as the signal transmission problem is imminent。 

This design in view of the subway in high-speed motion, body, cell switching and doppler frequency shift impact is analyzed in theory, and expounds the characteristics of wireless communication technology in subway, discuss the subway network coverage, the design scheme and technical breakthrough。 At the end of this paper the optical carrier radio over fiber (RoF) technology, using optical fiber communication, achieve faster transmission speed, low loss, high security features to solve the propagation loss of car body, the problems caused by frequent cell switching, subway wireless communication technology and the future development of the Wifi-ROF technology development put forward the construction scheme。