【作者】 朱铨；

【导师】 蒋新华；

【作者基本信息】 中南大学 ， 交通信息工程及控制， 2014， 博士

【摘要】 摘要：随着我国高速铁路的大规模建设及移动互联网应用的快速普及,迫切需要为车载快速移动环境下的用户提供更好的移动互联网服务,但目前尚有诸多挑战性问题,如：地面无线网络覆盖技术、车-地宽带互联机制、车-地互联流量管理以及车载移动互联网接入网络的智能化管理等。为此,论文开展了如下研究：通过对国内外研究现状的深入比较分析,论文设计了一种基于集中接入模式的四层车载移动互联网体系结构,并确定了论文待研究的六个关键技术问题。为实现对铁路交通干线沿线合理的无线宽带网络覆盖,论文提出了基于无线Mesh网络和3G/LTE/4G的地面无线专网建网策略,从而以较优的投资成本实现铁路交通干线沿线的无线宽带网络覆盖,并获得较好的传输性能。在实际网络部署中,可采用P层榕树型网络拓扑结构以提高实施的可行性。针对无线Mesh网络存在的多跳传输带宽急剧下降且传输时延快速增长的难题,论文建立了多跳无线Mesh网络骨干链路传输模型,对影响其传输性能的关键因素进行了深入研究,并设计了多模Mesh节点结构和正交频道分配方案。在此基础上,论文研发了基于IEEE802.11n标准和B.A.T.M.A.N. adv路由协议的无线Mesh路由器原型系统,实验结果表明其单跳传输基带宽大于140Mbps,经过八跳传输后的带宽仍大于60Mbps,且传输时延较小为实现车载通信网关在异构网络中的垂直切换,论文基于效用函数设计了异构无线网络垂直切换策略HWNHS,通过系统延迟容忍系数对传输链路进行灵活地选择,以实现最优的传输性能和最大的传输收益。由于车载移动互联网用户的快速移动特性,论文设计了快速无线Mesh网络切换算法FWMNSA。通过对其切换性能进行仿真研究,结果表明车载通信网关的移动速度、扫描时间间隔以及接入信道数将影响其切换成功的概率。同时,论文针对车-地互联的应用环境,设计了区内快速切换策略FSSFA以及车载通信网关的原型系统,实验结果表明,采用FWMNSA的车载通信网关可以实现Mesh节点间的快速切换,通过FSSFA策略,将使车载通信网关在Mesh节点间进行快速切换的传输时延降低至600-700ms,从而实现了车载通信网关在无线Mesh网络中的快速、无缝水平切换。为优化车-地宽带互联Internet流量的传输,提高用户的使用体验,论文基于ON/OFF模型和叠加模型建立了适合车-地宽带互联Internet流量的数学分析模型,并对车-地互联Internet流量的特性进行了研究,在此基础上设计了代理服务器的预取访问算法PAA,仿真和实验结果表明其能够明显提升车-地宽带互联链路在高负载情况下的承载能力。为实现对长距离、大规模的地面覆盖无线Mesh网络的智能化管理,论文建立了Mesh节点故障预测处理策略NFPPS,实现了对节点的链路通信质量、节点负载的自动感知,缩短了Mesh节点发生故障时网络重新收敛的时间,从而增强了网络的健壮性。在此基础上,本文开发了无线Mesh网络的本地管理平台和集中云管理平台,实现了对无线Mesh网络及Mesh节点实时、在线的智能监控与管理。图62幅,表30个,参考文献190篇。更多还原

【Abstract】 Abstract:With the large-scale construction of railways and the rapid spread of mobile Internet applications, the urgent need is to provide better Internet services for on-board users in the fast moving environment. Therefore, the current studies face the following challenges:the ground wireless network coverage, train-ground Internetworking mechanism, management for traffic of train-ground and intelligent management for on-board mobile Internet. The main works are as follows:Based on the research actuality, the four-layer centralized-access-mode-based on-board mobile Internet network architecture was designed. Then the six key technical problems which would research was determined.In order to realize the reasonable broadband wireless coverage along the railway trunk line, the private wireless network solution based on WMN and3G/LTE/4G was proposed. It would augment WiFi using3G/LTE/4G to obtain a higher bandwidth and lower investment. For the actual network deployment, the P-layer banyan-tree network topology was proposed to improve the feasibility of the implementing.For the problem of WMN which the multi-hop transmission bandwidth dropped while the transmission delay dramatically increased, the key main factors that influence transmission performance of the backbone link was researched based on the transmission model for backbone link, then the multi-radio mesh node structure and orthogonal channel allocation scheme was designed. On this basis, the wireless mesh router prototype system based on the IEEE802.11n standard and B.A.T.M.A.N. adv routing protocol was developed. Experimental results showed that its single-hop transmission bandwidth is greater than140Mbps, after eight hops the bandwidth is still greater than60Mbps, simultaneously has a smaller transmission delay. To achieve vertical handover in heterogeneous networks for on-board communication gateway, the heterogeneous wireless networks handoff strategy HWNHS based on utility function was designed. The system delay tolerance factor could be used to select the transmission link, in order to realize the optimal transmission performance and the largest transport income.For the fast-moving feature of on-board mobile Internet, the fast WMN switching algorithm FWMNSA was designed. By researched its handover performance through simulation, the thesis found that the moving speed, scan interval and the number of access channels would affect the handoff success rate of the terminal. Focus on the environment of train-ground Internetworking, the fast switching strategy for area FSSFA and the prototype system of on-board communication gateway was proposed. Experimental results showed that FWMNSA can realize fast switching and FSSFA will reduce the transmission delay of path update to600-700milliseconds, achieved the goal of fast and seamless switching.In order to optimize the traffic flows of train-ground Internetworking and improve the user experience, an Internet traffic model which is based on the ON/OFF model and overlay model was proposed to research the feature of Internetworking flows, then the prefetching access algorithm PAA was designed. Simulation and experimental results showed that the PAA can obviously improve the load capacity of the train-ground transmission link.To realize the intelligent management for the wireless coverage WMN, the node failure prediction processing strategy NFPPS based on B.A.T.M.A.N. adv was established, realized the automatic perception of the link quality and load capacity for mesh nodes, shorten the re-convergence time when the mesh node brake down, and enhanced the robustness of the network. Then the local management platform and cloud management platform for WMN were developed, realized the real-time, on-line intelligent monitoring and management for the WMN and Mesh nodes. There are62pictures,30tables and190references.更多还原