ATCS RF channel modeling using computer aided engineering

Abstract

A computer model designed to analyze the data communications network of the advanced train control system (ATCS) is discussed. The model was developed using Network II.5, which includes the hardware components and communication protocol of the ATCS data communications network. The model includes the RF channel access mechanism with busy bits. The effect of RF propagation on the system is modeled by assuming a message success rate and adjusting the traffic load accordingly. RF collisions resulting from operation of the busy bit channel access mechanism add to the load when they occur during the simulation. Typical results for the model based on an assumed traffic load are presented to illustrate how the model displays systems performance. A time-stamped record of message traffic over an operating ATCS communication system is compared to the model simulation for the same traffic. For this benchmark, the accuracy of the model is 80% to 91%.<>