Path Gain Modeling and Analysis of Channel in Tunnels with Different Antenna Positions and Polarizations

We investigate the path gain characteristics of the channel in tunnel scenarios with different antenna polarizations and different antenna positions based on an image ray tracing channel model. The results show that the path gain is greatly affected by the antenna positions, which will deteriorate when the antenna is moved from the center of the tunnel to near the wall and near the ceiling. The path gain with cross-polarized transmitting (Tx) and receiving (Rx) antennas is much worse than that with co-polarized Tx and Rx antennas. It can be also found that the effect of the antenna polarization is related to antenna position. When the Tx antenna is located near the wall, the path gain with vertical polarizations shows better performance than that with horizontal polarizations. When the Tx antenna is located near the ceiling, the path gain with the horizontal polarizations shows better performance than that with vertical polarizations. The results indicate that the communication performance in tunnels can be improved with proper antenna positions and antenna polarizations.