High Reliability Redundancy Method Of Train Communication Network

With the rapid development of high-speed trains,the bandwidth required for train communication networks is increasing,and fieldbus technology has been difficult to meet demand.Ethernet has been widely used in industry because of its high bandwidth,good compatibility and flexible topology.Ethernet-based train communication network has become a new research direction in the rail transit industry at home and abroad.In order to improve the reliability of the train communication network and realize the real-time data transmission of the train communication network,this thesis starts with the ladder topology protocol,studies the reliability problem and redundant management method of the train communication network topology,and studies the real-time scheduling method based on real-time MAC protocol.The main research results of this thesis are as follows:(1)Researching the topology and characteristics of the Ethernet Train Backbone network and the Ethernet Consist Network.The failure cases of different ECN architectures are analyzed,and the train communication network architecture based on ladder topology is established.Establishing a reliability model of network structure by Dynamic Fault Tree Analysis.Binary Decision Diagram and Markov matrix are adopted to resolve static and dynamic fault tree.The superiority of the ladder topology is verified.(2)Analyzing the operation mechanism of ladder topology protocol and the impact of End Device redundancy on system reliability,and the specific implementation scheme of ladder redundancy is studied.The ladder topology redundancy management method is designed to improve the reliability of the system.The basic requirements of the discarding algorithm are summarized.The redundant frame dropping algorithm based on dynamic linear HASH is used to reduce the data search and insertion time,and the effectiveness of the proposed method is verified.It lays a solid algorithm foundation for the application of ladder topology protocol on train communication network.(3)A ladder topology real-time scheduling method based on real-time MAC protocol is designed to improve the deterministic and real-time performance of traditional Ethernet based on CSMA/CD medium access control.The end-to-end delay components in the data transmission process are analyzed,and an example calculation is carried out.A token-based ladder topology fault detection mechanism is designed to realize the alternative transmission and fault recovery processing under fault.The method draws on the token idea,effectively solves the competition problem in the network,and improves the certainty and real-time of the network.(4)The trapezoidal topology network architecture is built by OPNET network simulation software.The normal and faulty transmission is simulated,and the high reliability and real-time performance of the ladder redundancy scheme is verified.A real-time Ethernet redundant network card with dual network adapters was designed,and a network communication verification platform was built by using nodes and switches.Through the platform,and the data packet is analyzed by the packet capture software.The test results show that the redundancy management scheme can meet the real-time and reliability requirements of the train communication network.Finally,the research content of the whole article is summarized,and the research direction of the next step is prospected.