Complex wall effect on fading and MIMO capacities for wireless communication environments

The two-dimensional finite-difference time-domain (FDTD) method is used to calculate the electric field distributions in an indoor communication environment with realistic floor plan. Power and fading characteristics (e.g., the Rician K-factor), and MIMO capacities are then calculated. Three different wall structures, i.e., the simple slab structure, the complex structure, and the effective slab wall of the complex structure, are considered and the corresponding K-factors and MIMO capacities are compared. It is found that the mean values of K-factors of the complex wall cases are larger than that of the slab walls by around 3 to 5 dB, while the K values of effective walls are larger than those of the complex wall cases by as much as 7 dB. It is also shown that the complex wall structures give larger MIMO capacities in most cases and the effective wall structures give the lowest MIMO capacities in all cases. Based on these results, it may be concluded that the complex wall effect on the propagation characteristics and the MIMO capacity may not be appropriately approximated by those estimated based on effective wall structures.