Measurement and Modeling of Channel Characteristics with Leaky Coaxial Cable in Railway Tunnels at 2.1 GHz

With the rapid development of railway transportation, the reliability of communication systems in tunnels has become the key to improving signal transmission quality and ensuring driving safety. Leaky coaxial cable (LCX) is the main way to cover wireless signals in tunnels. Its uniform radiation characteristics make the wireless channel characteristics different from those of traditional communication scenarios. Aiming at the wireless channel characteristics of the 5G-R target frequency band covered by LCX in railway tunnel scenarios, this paper conducts a study on the measurement and modeling of wireless channels at 2.1 GHz. Based on the measured data of straight tunnels and curved tunnels, the large-scale and small-scale fading of the wireless channel under the LCX coverage are analyzed. The research results show that the path loss under the LCX coverage in the tunnel can be represented by a linear model, and the small-scale fading distribution is consistent with normal distribution and Rice distribution. In addition, due to the uniform radiation characteristics of the LCX, the channel characteristics of the curved tunnel are very similar to those of the straight tunnel. The research results can effectively reflect the wireless channel characteristics of the tunnel covered by LCX, and provide a theoretical basis for the design and optimization of the railway communication system in the tunnel.