Measurement-based auto-correlation model of shadow fading for the high-speed railways in urban, suburban, and rural environments

In order to maintain reliable communications in high-speed railways (HSR), new and better handover algorithms must be developed. A deep understanding of the correlation properties of shadow fading, which is the basic of designing a handover scheme, is thus required. In this paper, an auto-correlation model of shadow fading in HSR environments is proposed based on a large body of measurements in China. The measurements are conducted along the HSR lines in urban, suburban, and rural environments, respectively, using a practically deployed and operative GSM-Railway system at 930 MHz. It is found that the auto-correlation coefficient follows an exponential decay function. The decorrelation distance is around 57 m in urban, and is larger than 110 m in suburban and rural environments. The results can be used for the design of diversity and fast handover schemes.