Research On Real-time Performance Of Train Communication Network Based On Switched Ethernet Technology

Due to the Ethernet technology has advantages of high transmission rate and low cost, rail transit industries from both international and domestic are working on the development of train communication network based on Ethernet. To comply with this trend, this thesis focuses on improving Ethernet deterministic and real-time performance methods to meet the needs of train communication network without modifying the Ethernet general chip. The main contents and innovative points include the following aspects:(1)Through a deep research on factors affecting deterministic and real-time of Ethernet, an improved method was introduced in this thesis. This thesis suggests the solution of full duplex switched technology in dealing with the deterministic of Ethernet. Furthermore, a topology of train communication network which is based on switched Ethernet is designed, and a detailed analysis of the factor of data end-to-end delay is made.(2)Based on a comprehensive analysis of train communication network, this thesis proposes a mixed priority scheduling mechanism, which may effectively decrease the queuing delay of train real-time data in switch buffer queue. The calculations of the upper bound of train real-time data end-to-end delay are listed at the priority queuing scheduling mechanism and mixed priority scheduling mechanism. In addition, models are established to testify the superior of the mixed priority scheduling mechanism through the network simulation technology.(3)According to the design problem of switched Ethernet topology, mathematical models were built up. This thesis comes up with the approach of solving the train switched Ethernet optimal topology through adopting immune genetic algorithm with satisfying the demand of all real-time data stream. Furthermore, a real case is used to verify the feasibility and effectiveness with the approaches of theoretical calculations and network simulation.(4)Through depth analysis of TDMA mechanism, a real-time Ethernet test network segment based on TDMA mechanism in lab environment is set up in this thesis. With designing a variety of test scenarios, the author sums up the principle of TDMA mechanisms slice division and verifies the improvement of Ethernet on applying TDMA mechanism.