Research On Real-time Data Transmission Of New Train Control System Based On All IP

In order to realize the optimization of the urban rail transit signal system,a new train control system based on vehicle-to-vehicle communication,all-IP architecture and cloud computing technology has been proposed.It has now become the main development direction of urban rail transit in various countries around the world.While the new train control system simplifies the overall structure,it also places higher requirements on the real-time performance of data transmission between devices.In addition,since urban rail trains frequently trigger handovers during the travel process,the real-time performance is seriously affected.The existing retransmission method with equal retransmission interval will only further aggravate network congestion.Therefore,it is critical to adopt new transmission structures and retransmission methods to improve the system’s real-time performance under communication degradation conditions such as handover.At the same time,countries all over the world are promoting the integration of cloud computing into the train control system.The efficiency of different cloud platforms and the real-time data transmission with locals are important research directions that urgently need experimental verification.This article first introduces the organizational structure and working principle of the new train control system to summarize its characteristics in data transmission.At the same time,it explains the LTE wireless communication technology,focusing on the analysis of the impact of handover on time delay under the coverage of LTE network,indicating that it is crossed.Switching is the main reason that affects the real-time performance of urban rail transit data transmission.Later,a distributed data transmission structure based on the communication controller was proposed,and the advantages of the new train control system using this structure in the deployment of cloud computing were explained.In order to improve the real-time performance of data transmission,this paper draws on the idea of time triggering,and proposes the use of variable retransmission interval time triggering method to reduce the transmission delay of the system when handover occurs,and uses random network calculations for data between on-board equipment The transmission scenario is modeled,the equal retransmission interval mode and the variable retransmission interval time trigger mode are compared,the arrival curve and service curve of the normal service flow are analyzed respectively,and the delay boundary is derived.The simulation results show that the variable retransmission interval trigger mode can effectively reduce the system delay boundary value.Finally,the real-time performance is verified based on the laboratory platform.Use MAX10 FPGA and W5500 Ethernet controller to design the hardware composition of the host and communication controller,and write the corresponding code to realize the logic control function of the host to the communication controller and the external communication function of the communication controller.At the same time,the software is used to simulate the wireless communication scene of urban rail transit,and the transmission delay of the system under the action of two retransmission methods is tested separately.Experimental results show that under the 100 ms transmission period,the variable retransmission interval method can reduce the transmission delay of the system during handover by 8.23%,which can achieve the purpose of improving real-time performance.Next,build two cloud platforms,Openstack virtual machine and Docker container,to test the real-time data transmission between local devices and devices on the cloud,and compare them with physical servers.The test results show that the container method is superior to the virtual machine method in terms of real-time performance,and is a cloud computing implementation method that is more suitable for the use of the new train control system,but both have a large gap with the physical server.In addition,based on the test results of the physical server,this article makes a reasonable speculation on the real-time performance of the bare metal server,and believes that the bare metal server has significant advantages in real-time and efficiency.