Research On Real-time Performance Of Data Transmission In Urban Rail Train Sensor Network

This paper is based on urban rail train sensor network project, including access point, fusion point and test evaluation platform(national863program). Study and design on the construction of urban rail train sensor network platform. The domestic train control technology are introduced fromabroad, and we are lack of own intellectual property rights.Especially there is no independent, high-capacity, systematic train running safety inspection system, to provides the guarantee on reliable, punctuality and the safety of train running. Focus on the urban rail operation security features in our country, to establish a standardized, systematic urban rail train sensor network is of great significance.Firstly, put forward the development direction of train communication network, it do some reference for urban rail train sensor network.And the function structure of sensor networks, network structure, the sensor data transmission are analyzed.In addition, the technical problems existing in the sensor network is proposed. Pointing out the main work on the establishment of urban rail train sensor network is to solve the problem of the gateway node scheduling strategy, in order to meet the requirements of platform in real-time.Secondly, design an urban rail train sensor network data transmission platform, this can emulate the actual operation of network and system. And theEthernet communication technology is introduced. Starting from the angle of the functional requirements of the platform, design the function of network node. From the network reliability to design thenetworking mode of network function node.Set up a data acquisition layer,data collectionlayer,data access layer, data transmission layer,and data processing layer consisting of four layer network structures. According to the function definition of functional nodes chooses equipment, construct a physical platform. Design data transmission simulation system, to realize the data transmission function of platform.Again, analyze the main influencing factors in data transmission platform of urban rail trains sensor network.It is concluded that the queuing delay is the largest influence.In order to reduce the data transmission delay, IEEE802.1P standard frame structure deadline field is introduced, and in the gateway has designedthe FCFS with EDF scheduling policy under the priority queue. By using opnet simulation technique to identity the effectiveness of the improved scheduling policy.Finally,do some improvements in the delay modelabouturban rail trainsensors network。Using the improved delay model to evaluate the performance of real-timetransmission.The Service Curve is defined according the working principle of hybrid scheduling in the network calculus. Calculate transmission delay of urban rail train sensor network about data transmission platform. The analyzing results concluded that the network delay is less than the data delivery cycle. Thus, the real-time performance of data transmission platform can be guaranteed.