Research Of QoS And Routing For WSNs In High-speed Railway

At present, the high-speed railway has gradually become the main force of China’s railway transportation because of its remarkable feature of high speed, little pollution, high comfort, fast and punctual, while the characteristic of high speed also puts forward a higher requirement of the operating environment monitoring of the high-speed train. Fortunately, a wireless sensor network (WSN) has a favorable capacity of monitoring and can remote monitor and control, and is used to apply to many fields. Thus, applying WSN to high-speed railway will be a meaningful topic. For the research of QoS in WSN, most of the existing literatures are aimed at the general sensor networks without combining with the specific application scenarios, which results in that these works are not suitable for application in high-speed railway directly. In addition, the research on routing algorithm in WSN, most resluts search for the feasible optimal routing from the view of optimizing single index, such as to maximize the lifetime of the network, to shortest the path or balance the energy load, all of which do not take into account of the mutual restriction relationship among indexes. In this paper, combined with the environment characteristics of high speed railway, the QoS indexes which can significantly reflect the performance of WSN are selected and a QoS index system is constructed. Considering the different ways of nodes’deployment along the track and in scenarios, we study routing algorithms for WSNs in high-speed railway for two scenarios.The main research works in the thesis are as follows:The first chapter introduces the significance of application of WSNs in high-speed railway and the research status of related works.The second chapter analyses both the deployment characteristics of sensor nodes in high-speed railway and the requirement of different type nodes for monitoring environment. Then, combined with the network performance and cost, the selection of performance indexes is conducted and a relatively sophisticated QoS evaluation index system for high-speed railway operating environment is proposed which is based on the correlation among the indexes. Finally, the quantitative relationship among indexes is given by using the analytic hierarchy method.The third chapter studies respectively the problem of routing along the track and routing in typical environment respectively in terms of the different ways of node deployment in two different scenarios. For nodes deployed along the track constitute a linear network, this thesis gives several different routing algorithms and makes a comprehensive evaluation for these algorithms based on QoS evaluation index system, then a method for deploying and routing which is suitable for the nodes along the track is proposed. While the nodes in typical scenarios are deployed irregularly, which build a regional type network. For a routing problem with multiple indexes to be optimized simultaneously, the multi objective constraints is constructed as an objective optimizing function which is solved by an improved ant colony algorithm. Finally, the effectiveness of the given algorithm is illustrated by simulation.The fourth chapter concludes the main research works of the thesis and prospects some research issues in future.