Effect of array orientation on capacity of MIMO wireless channels

Orientation of receive and transmit antenna arrays is always omitted while researching the capacity of wireless channels. This paper investigates the effect on capacity of MIMO (multiple-input multiple-output) wireless channels and obtains that the effect can not be neglected while either the angular spread being small, and that antenna arrays should be rotated to make the array's normal point to the mean direction of arrival or departure (DOA or DOD) to attain more capacity. Simulation results show that orientation of the array with smaller angular spread dominates the effect on MIMO channels capacity and that increasing angular spread diminishes, or even eliminates it.