Providing Wireless Bandwidth for High-speed Rail Operations

American railroads are in the process of introducing a wireless network-based control system – commonly referred to as positive train control (PTC) – to share the railroad among multiple trains, worker vehicles, and other support entities. A major challenge with adopting a wireless based communication systems for high-speed rail (HSR) is the limited bandwidth availability in the USA. The objective of this paper is to analyze the sufficiency of the 220 MHz frequency range in supporting PTC-like operations for high-speed trains.The paper begins with a frequency analysis that shows the advantages of using different modulation schemes and channel bandwidths to gain data rates and supporting signaling and beacon networks that uses PTC packets formats. PTC places limitations on the wireless trains speeds with the number of packets required to establish a connection and a minimum distance between overlapping cells, using proposed packet formats. Additionally, using a guard band that can eliminate the Doppler effect caused by increasing train speeds. For example, using a guard band of 300 Hz can eliminate the Doppler shift at speeds less than 400mph.