Modeling And Implementation Of TCN Underlying Protocol

Train Communication Network is the core technology in the modern train. This paper is based on the major research project - "Research of TCN low-layer protocol and key technology" which is carried out by the Ministry of Railways. The application of the train communication network has been the necessary steps to provide a more safe and faster railway experience. As a main part of the train control system, the train communication network has to have high real-time and high reliability and high safety performance. We have been late on the research of the TCN, and we still lag far behind the foreign vendors. This paper mainly studies the key problems related with the performance evaluation, optimization and the interface implementation method. It can be divided into four main parts:1. Aiming at the dynamic performance evaluation of the train communication network, the paper presents the methods to model the field bus, and it points out that the Petri net is the best way to model the distributed, discrete, concurrent, stochastic systems. General Stochastic Petri Network (GSPN), Determentic and Stochastic Petri Network (DSPN) and Stochastic Colored Petri Network (SCPN) can be used in the different level in modeling the field buses. The method to analyze the performance of field bus is talked. With the development of the hardware and software, the method based on the simulation will be the main method to solve the Petri net. To analyze the performance of the MVB, the GSPN model of MVB, and SCPN model of the MVB events arbitration, and the CPN model of the MVB are presented in the paper, and the results are also given. The GSPN model is used to analyze the performance of pure process data throughput. The model of events arbitration can be used to analyze the relationship between the event arbitration performance and the time width of stochastic phase, the similarity of the device address and the uniformity of stochastic phase. From the analysis, the optimization problem of the period polling table is proposed. After comparing the Petri nets modeling method and the discrete event simulation method, the TCN simulation method combined with SCPN and OMNET++ is proposed. This method is more suitable to analyze the real TCN.2. To maximize the message transmitting performance on the premise of reliability of process data scheduling, an optimization method of the MVB period polling table is presented. Based on the basic definition of the period polling table, the shortage of the recommended method in IEC61375-1 standard is talked. Two methods have been proposed to solve the two different problems. The first named filling step by step method can be used to construct the period polling table that was time independent. And the time dependent problem is solved by the hybrid genetic algorithm. The model of the TPPT problem has been presented, and the target function, and other related problem have also been given out. The computing result presented in the paper proved that these methods can optimize the MVB period polling table efficiently. To overcome the shortage of the genetic algorithm and increase the optimization speed, the hybrid chaos and genetic algorithm based on the S-Tent map is proposed. The S-Tent map has better ergodicity, and the scaling method of the chromosome is also given. The result showed that this method is an effective method to optimization the period polling table.3. The fusion method of the mvb bus controller and application processor using SOPC technology is presented, based on the independently designed bus access IP core. The MVB bus controller is the main parts to implement the bus access function. The controller worked with an application processor commonly. This paper has given the interface implementation method of the MVB bus controller, the application processer and the controller is integrated into one FPGA chip using the SOPC technology.4. The TCN hardware-in-the-loop simulation platform is created to complete the experiment and test of the TCN. On this platform the interface implementation method proposed in this paper can be verified, and the performance measurement can be done. This platform includes the equipment on the driver's desk and the other large equipments are simulated by the PC software. The experiments can verify the correctness of the model, the optimization method and the implementation method proposed in this paper.In the last part, the paper presents the research conclusions, proposes the innovative ideas, and points out the remaining problems that need further research.