MIMO Channel Model and Correlation between Channel Matrix Elements in Multipath Channel

To clarify MIMO channel complex correlation for various cell types, we studied the correlation analytically and by computer simulation. We prepared a MIMO channel model consisting of base and mobile antenna configurations and a delay profile with arriving and incident wave angles (ξ_n, ζ_n) in line-of-sight (LOS) and non-line-of-sight (NLOS) paths. Then, the general correlation formula ρ_i-j,i´-j´(bm) was derived for the model. It shows that ρ_i-j,i´-j´(bm) depends on two factors: antenna configuration at mobile and base sites (z_i-i´, z_j-j´, Ψ_i-i´ , Ψ_j-j´) and angle distribution (ξ_c, Δξ_n, ζ_c, σ). It also shows that ρ_i-j,i´-j´(bm) is expressed as the addition of a directive wave term kexp(jdθ₀) to the product of mobile site correlation ρ_i-i´(m) and base site correlation ρ_j-j´(b) without LOS, which are calculated independently of each other. So, the formulas for ρ_i-i´(m) and ρ_j-j´(b) were derived for uniform and Gaussian angular distributions. Furthermore, a computer simulation was performed and the simulated and theoretical values agreed well. Therefore, we can apply the ρ_i-j,i´-j´(bm) to various cell types indoors and outdoors by combining them, so it is possible to calculate the correlation between MIMO channel matrix elements for a given cell and environment.