摘 要： 轨道交通系统中的各车-地信息传输方式有GSM-R、应答器、感应环线、WLAN等，本文对各种通信方式做了对比分析，得出了 WLAN的无线车地通信方式相对于其它系统，具有良好的标准性及传输效率。因此，重点对基于 WLAN 的车地信息传输方式做了详细分析。分析了影响 WLAN 性能的电波传播特性，工作频段，吞吐量稳定性，系统冗余以及无缝切换等。 结果表明： 基于IEEE802.11n 的 WLAN 近距离传输、 接入速度快、系统容量较大，抗干扰能力强；在传输带宽上足够满足要求，冗余覆盖较容易实现。在此基础上设计了基于WLAN的车头车尾双网冗余的车底无线通信系统。 采用一个嵌入式封装转发模块，将车载数据进行数据二次封装并冗余发送。并通过 socket 编程实现车载视频封装转发模块，将视频编码器的数据包以相同的备份发往车头车尾不同的子网，实现数据的冗余传输。最后根据设计的原理搭建了系统的测试模型，对模型进行了吞吐量与视频传输的测试，测试结果表明：基于 802.11n 的车头车尾双网冗余车地无线通信系统具有较高的鲁棒性，针对列车运营时 WLAN 总是会发生的硬切换丢包现象，给出了完备的解决方案。20193
关键词： 无线；车地通信；点式通信；连续通信；WLAN
Analysis and Design of train-ground communication mode
in rail transport
Abstract：The information transmission mode in rail transport system includes GSM-R,
transponder, induction loop, WLAN, etc This paper does comparative analysis on each
transmission mode to get the result that WLAN has a good and standard transmission
efficiency. Thus, the paper focuses on making a detailed analysis on information transmission
between the train and ground based on WLAN. It analyzes the characteristics of radio wave
propagation which influences WLAN performance, working frequency, throughput stability,
system redundancy, seamless switching, etc As the result shows, it has quick access speed,
large system capacity and strong antijamming capability based on short distancecommunication in WLAN with IEEE802.11n. It is enough to meet the demands on the
transmission bandwidth, and it is easy to achieve redundant cover. On this basis, the paper
designs wireless communication system under the vehicle which has WLAN dual-redundancy
network on the front and rear of vehicle. It uses an embedded encapsulation transmitting
module to make vehicle data have secondary encapsulation and then sends it out. Socket
programming makes it realize the encapsulation transmitting module with on-board video. So
the same backup of video encoder’s data packet can be sent to the different subnets on the
front and rear of vehicle, which achieves redundant data transmission. In the end, it establishes
system test model which tests the throughput and video transmission according to design
principle. As the test result shows, such wireless communication system has high robustness.
Moreover, complete solution is given to WLAN which has hard-switching and data loss when
the train runs.
Keywords: wireless; train-ground communication; dot-communication; continuous
communication;WLAN 目 录
1 绪论1
2 车地通信方式对比分析. 4
2.1 车地通信方式的分类.4
2.1.1 点式通信4
2.1.2 连续式通信5
2.1.3 车地通信方式比较6
2.2 无线通信式车地通信的对比研究.7
2.2.1 GSM-R7
2.2.2 卫星通讯8
2.2.3WLAN.9
2.2.4WiMAX.9
3 基于 WLAN的车地无线通信分析.12
3.1 无线局域网 IEEE 802.11标准分析对比 12
3.2 无线局域网的PHY层和 MAC 层. 14
3.2.1 无线局域网的物理层(PHY).15
3.2.2 无线局域网的媒体接入控制层(MAC)15
3.3WLAN 应用于轨道交通车地无线通信时的特殊考量.16 轨道交通车地通信方式分析与设计:http://www.751com.cn/tongxin/lunwen_11869.html