Modeling and performance evaluation of an rf transceiver system at 160 mhz for railroad environments

With the continued proliferation of wireless applications across North America's railroad industry, it is vital to explore performance capabilities and constraints across different wireless frequency bands, including the impact of characteristics of the RF environment. In this study, our efforts are directed towards a traditionally underutilized wireless frequency band available to the railroad industry, at 160 MHz. While this frequency band is currently primarily utilized for limited voice communications, our interest is to explore it for modern data applications. This exploration includes an evaluation of end-to-end performance characteristics. In order to carry out such a study we simulate our 160 MHz communications system utilizing various channel models, e.g., FSPL, Two-Ray Ground-Reflection, Okumura and Winner2. In this communications system, our design of the transmitter and receiver addresses real-world signal impairments, such as carrier frequency and phase offset that may result from the modelled channel. We evaluate the communications system for QAM-modulated signals with different modulation orders ranging from 2 to 256. The parameters of the transmitter and receiver structures are evaluated for maximizing communication throughput while adhering to channelization, spectral mask, and power requirements. We present and discuss practical and theoretical throughput results for different channel models. The various channel models investigated in this study can be utilized to represent different railroad environments such as rural, urban and suburban areas. This study provides the basis for our efforts to fully develop a data communications system for the 160 MHz frequency band in support of vital railroad applications, such as expanding spectrum access for Positive Train Control.