Effects of spatial correlation and associated parameters on the capacity of MIMO fading channels

The effect of spatial correlation on the capacity of multiple-input multiple-output (MIMO) fading channel with uniform linear arrays (ULAs) at the transmitter and receiver is investigated. The situations when the channel is known and unknown at the transmitter are considered. The effects of antenna spacing, angle spread, and number of antennas on the capacity are also investigated. Extensive Monte Carlo computer simulations are carried out. The results showed that the spatial correlation may severely degrade the capacity of MIMO systems. The degradation in the capacity can be reduced by increasing the separation distance between the antenna elements. However, increasing the antenna spacing beyond ≈ 2λ has no effect on the capacity. Small angle spread leads to higher correlation between the antenna elements and consequently lower capacity.