Non-stationary channel characteristics in high-speed railway

To measure the channel variability in high-speed railway, a non-stationary metric is chosen, which is defined as the correlation of consecutive signal power samples. And the time interval is determined within which the power correlation exceeds a certain threshold. Based on this metric, the channel non-stationary characteristics of four scenarios, which are cutting, low viaduct, high viaduct and tunnel, are investigated through measurement data. And the propagation mechanism is analyzed for each scenario.