Measurement-based research on Ricean K-factor of broad-band wireless channel in high-speed railway scenarios

Owing to higher and higher requirements for communication between the high-speed train and the ground, the existing narrow-band train control system (GSM-R) has been commonly recommended to be evolved smoothly into a broadband railway communication system based on long term evolution (LTE-R). Wireless channel measurements and parameter extraction are the prerequisites for designing of the novel wireless communication system. The Ricean K-factor is a fundamental parameter of the wireless channel, which directly reflects the fading severity and communication quality. Consequently, deep research on such a characteristic of railway wireless channels is of utmost importance. In this paper, narrow-band and broadband K-factor were extracted respectively from channel data measured in the viaduct scenario of the Zhengzhou-Xi'an (ZX) High-speed Railway. For the narrow-band K-factor, the characteristics of time and frequency variability were analyzed and a distance-dependent statistical model was built. For the broadband K-factor, the law of its changing with bandwidth was explored and a bandwidth-dependent statistical model was built. Finally, the K-factor variation with different delay bins was discussed.