Measurement-based Fading Model with Leaky Coaxial Cables for Urban Rail Transit in Tunnels

摘要

Dispatcher commands should be executed accurately and timely, which are transmitted to train drivers through Trans European Trunked Radio System (TETRA) at 860 MHz. In order to increase the reliability and availability, leaky coaxial cables are utilized to provide stable communication channel and anti-interference capability. In the paper, a fading model with leaky coaxial cables in tunnel is developed based on filed measurements in Beijing Subway Line 7, where characteristics of large scale fading and small scale fading are demonstrated. Through the polynomial fitting, it is found that a fading model of large scale fading with leaky coaxial cables is linear. Based on AIC (Akaike information criterion), the small scale fading is close to the normal distribution. The results can be used for the design of wireless communication networks and the parameter optimization of handoff schemes.