Spatial correlation measurements for broadband MIMO wireless channels

In this paper, we propose a method to determine the transmit and receive side spatial correlations for an arbitrary antenna spacing in the arrays from a directional MIMO channel measurement. A broadband MIMO channel measurement platform has been developed, which is used to obtain the angles of arrival (AOA) and angles of departure (AOD) of resolvable multipath components (MPC). The AOAs and AODs are estimated from the measured MIMO channel data by using a sequential unitary ESPRIT algorithm. The measured AOAs, AODs and corresponding powers of the MPCs are used to compute the power angle spectrum for the transmitter and receiver sides of the MIMO propagation channel. The spatial correlation matrices and MIMO capacity can then be obtained from these directional measurements. Capacity results from the correlation measurements using a stochastic broadband MIMO channel model are observed to closely match the directly measured MIMO capacity for different propagation conditions and antenna spacings.