Impact of array orientation on performance of MIMO wireless channels

Orientation of the receive and transmit antenna arrays is always omitted in research on wireless channel performance. The paper investigates the impact of array orientation on both spatial correlation and the capacity of MIMO (multiple-input multiple-output) wireless channels. It is found that the impact cannot be neglected if angular spread is small, and that an antenna array 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. Numerical results verify the impact on spatial correlation, which increases with the array´s normal deviating from the mean DOA or DOD. Simulation results show that the orientation of the array dominates the impact on MIMO channel capacity under small angular spread, and that increasing the angular spread diminishes the impact, or even eliminates it.