Traffic impact on radio wave propagation at millimeter-wave band in tunnels for 5G communications

In this paper, the impact of truck convoys on radio wave propagation at the mm-wave frequency band in a two lane road tunnel is analyses by computer simulations. The analyzes reveal that the propagation of radio waves is not affected outside the convoy if a convoy occupies only one lane, while two convoys in both lanes cause serious drop of signal level behind the convoys. The signal level is decreased and delay spread is increased within the convoy, which suggests the usage of the vehicle to vehicle communication within a convoy. In addition, due to misalignment of transmitting and receive directional antennas a significant signal gap is occurred close to the base station. We suggest the usage of two antennas at the base station, one omnidirectional to cover proximity areas and the second one directional to cover distance areas along the tunnel.