Shadow Fading Correlation in High-Speed Railway Environments

In the design of diversity and fast handover schemes for high-speed railways (HSRs), a better understanding of the shadow fading correlation properties is required. In this paper, both auto- and cross-correlation models of shadow fading in HSR environments are proposed based on a large set of measurements with 6146 cells in China. The measurements are conducted using a practically deployed and operative Global System for Mobile Communications-Railway (GSM-R) system at 930 MHz to reflect the real conditions of shadow fading in HSR environments. Seven typical HSR environments and the realistic base station (BS) parameters are considered in the analysis. It is found that the decorrelation distance is correlated with the standard deviation (STD) of shadow fading and is generally larger than 100 m in most HSR environments. The cross correlation of shadow fading between two neighboring BSs depends on the BS height and the tilt angle of the antenna, and a heuristic truncated Gaussian distribution model of cross correlation is proposed. The model is validated by the measurements conducted in another operative HSR line. The results can be used to exploit the simulation algorithms to analyze the signal-to-interference-ratio (SIR) properties and to develop new and better handover schemes for HSRs.