Design and Analysis of 220 MHz RF Communications for Interoperable Positive Train Control System

The interoperable positive train control (PTC) system uses radio frequency (RF) in the 220 MHz band for wireless communications. Robust and reliable 220 MHz RF communication is critical to the success of the interoperable PTC system. To ensure proper operation of the interoperable PTC system, it is thus crucial to properly engineer and evaluate RF performance of communications from wayside devices and base stations to trains operating along PTC controlled track. This paper presents a design of wireless communications over the 220 MHz band for the interoperable PTC system. Performance of the designed 220 MHz PTC communications is analyzed and theoretical predictions are provided. The paper also presents a simulation system architecture for analyzing the performance of PTC communications over the 220 MHz band. The simulation system test bed integrates a message generator, RF channel simulator, and PTC software-defined radio prototypes configured as a base, locomotive, or wayside radio. Extensive simulations were conducted to determine RF performance of PTC radio communications in various scenarios including flat terrain and city environments. Simulation results are given and compared to the theoretical predictions.