Covariance-based Spatial Channel Structure Emulation for MIMO OTA Testing

The paper presents a general framework for recreating the spatial channel structure in a MIMO over-the-air (OTA) multiprobe anechoic chamber testing setup. The idea is to find the power weights of the spatial taps (antenna probes) that minimize a certain distance between the spatial channel covariance matrix corresponding to the desired (continuous) channel and the covariance related to the emulated (discrete) channel within the test area. Unlike previous methods that merely rely on the spatial correlation coefficient, the proposed approach properly accounts for emulating the power imbalance among the antennas-under-test by considering the whole spatial covariance structure. The simulation results validate the improved performance of the suggested approach in terms of emulation accuracy compared to the key emulation methods proposed in the literature.