Research On The Scheduling Policy Of Train Control And Service Network On Differentiated Service

With the rapid development of high-speed train and information technology,the train communication network has been widely used in the train,especially,in high speed train.The train communication network can realize train control information transmission.But with the rapid development of mobile intelligent devices and the improvement and popularization of network services,the people to improve the ride comfort requirements,It is extremely urgent for trains to provide Internet service to passengers.The following question is how to transmit the large amount of traffic which generated by the network service? and is the train original control information affected in the transmission? In the integrated transmission environment of train control and passengers service data,how to ensure the safety of train control information transmission and then provide high quality network services? All these problems need to be further studied.The national science and technology support program--"train control and information service network(TCSN)’ key technology and system development" was proposed for this purpose.Based on the technology project,this paper’s purpose is the design and implementation of TCSN scheduling algorithm.Based on the research analysis of train communication network at home and abroad and the scheduling algorithm,according to the requirements and features of the transport business,DWDRR/PRI,a two-level scheduling scheme for TCSN environments,was designed,and the first-level scheduling algorithm DWDRR and the second –level scheduling algorithm PRI were studied and implemented.First of all,according to distinguish service demand of TCSN,through researching the interface documentation and the papers of passenger service business,analyzeing the types of train control business and passenger service business,and the characteristic and transport service demand of all kinds of flow,the TCSN business flow model is designed and the simulation flow is generated based on the business flow model.Through TCSN business classification method,the corresponding relationship between each business and DSCP value was determined.Secondly,according to the characteristics of TCSN,the traditional WDRR scheduling algorithm is improved,and a new DWDRR scheduling algorithm is proposed.considering the different flow characteristic of TCSN business flow,transmission requirements,and the current network utilization,when the two-level scheduling scheme DWDRR/PRI was designed and the scheduling algorithm of detailed design was completed.Again,scheduling quota and weight calculation were simulated and verificated by MATLAB.Finally,the performance parameters such as the delay and loss rate of the three classical scheduling algorithms were simulated by OPNET,and compared with the performance of the two-level scheduling scheme.The effectiveness and advantages of the two-level scheduling scheme are verified by the comparison.