Research On DCS Network Information Security Of Urban Rail Transit And Implementation Of Network Monitoring System

The Data Communication System(DCS)is one ot the most important subsystems of communications based train control system(CBTC).Therefore,the protection of DCS information security is very important for the safe transportation of Urban Rail Transit.The traditional information security protection technology will not satisfy the future requirement because of the grim situation of information security in the future.Therefore,the research on the information security technology suitable for the urban rail transit is beneficial to handle the increasing threat of information security.The main work of this paper is as follows:Firstly,we analyze the weakness of DCS information security based on WLAN and the possible attack.Through the analysis of characteristics of the wireless communication network of Urban Rail Transit,different states of wireless terminal of train are defined.By combining the states of wireless terminal and wireless intrusion detection,the detection ability of wireless intrusion detection is improved.The paper describes the state of the wireless terminal by finite state machine,and analyses the whole process of access.Then,based on the static detection of wireless intrusion detection,we design a wireless intrusion detection algorithm according to the train state.Secondly,we present the minimum variable delay clock synchronization algorithm.When analyzing the clock synchronization of wireless communication system,it is found that the clock synchronization accuracy is affected by the high speed movement of trains.The main reason for the decrease of clock synchronization accuracy is the retransmission of data in data link layer.In order to improve the precision of clock synchronization,this paper proposes a minimum variable delay clock synchronization algorithm based on the traditional clock synchronization technology.In order to improve the accuracy of clock synchronization,the minimum variable delay clock synchronization algorithm is proposed based on the traditional clock synchronization technology.The simulation results show that the proposed clock synchronization algorithm can effectively improve the accuracy of clock synchronization.Thirdly,the design and development of DCS network monitoring system software is completed.The wireless intrusion detection algorithm based on train status and the algorithm of minimum time delay clock synchronization are implemented in the software.At the same time,the system has the function of monitoring the working status of the network equipment,detecting the legitimacy of the wireless terminal,discovering the abnormal situation of the network in time and displaying the alarm.The software has been successfully applied in the Beijing Metro Yan Fang line in the actual system.