Optimal MIMO Antenna Geometry Analysis for Wireless Networks in Underground Tunnels

The MIMO (Multiple Input Multiple Output) systems can efficiently mitigate the severe multipath fading effects in underground tunnels. Due to the unique tunnel channel characteristics, there exist optimal antenna geometries that can maximize the MIMO channel capacity. In this paper, an optimal MIMO antenna geometry design scheme is developed based on the analysis of the channel capacity in underground tunnels. The MIMO channel capacities in both empty tunnels and tunnels with obstructions are analytically expressed to facilitate the antenna geometry design. Simulation results show that the MIMO system with designed antenna geometry has obvious improvements in channel capacity than the system with the traditional linear array antenna geometry.