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(jdθ
₀
) 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.