### OPNET PROJECTS TOPICS

## Modelling delay propagation within a train communication network

Industrial Ethernet has been widely used in Modern HighSpeed Train Communication Networks (HSTCN). The reliability of HSTCN influences train safety. And time-oriented reliability is an important part of the HSTCN reliability. In the situation of node dependency, it is a difficult problem to analyze delay propagation for HSTCN. In order to solve the problem, we have done the following work. First, a delay analysis model is built based on discrete-time queuing theory and queuing delay and time-oriented reliability on each switch port can be calculated.

Second, the delay propagation model of HSTCN is proposed. The propagation delay on each port can be calculated, and then we evaluate the influence of the “ripple effect”, which leads to the propagation of these delays, and causes other ports queuing delay to increase. Third, an efficient algorithm for computing queuing delay, time-oriented reliability and propagation delay is developed, and we can calculate results quickly for HSTCN with complex topology. Last, simulation verification using OPNET for delay analysis modeling is completed. The results show that the proposed methodology is useful and effective in design engineering of HSTCN.