On Dynamic Channel Emulation in Sector MPAC for Over-the-Air Testing of Beamformed Massive MIMO Devices

In this article, novel emulation strate-gies for the sectored multiple probe anechoic cham-ber (SMPAC) are proposed to enable the reliable eval-uation of the massive multiple-input multiple-output (MIMO) device operating at beamforming mode, which requires a realistic non-stationary channel envi-ronment. For the dynamic propagation emulation, an efficient closed-form probe weighting strategy mini-mizing the power angular spectrum (PAS) emulation errors is derived, substantially reducing the associ-ated computational complexity. On the other hand, a novel probe selection algorithm is proposed to re-produce a more accurate fading environment. Vari-ous standard channel models and setup configurations are comprehensively simulated to validate the capac-ity of the proposed methods. The simulation results show that more competent active probes are selected with the proposed method compared to the conven-tional algorithms. Furthermore, the derived closed -form probe weighting strategy offers identical accu-racy to that obtained with complicated numerical opti-mization. Moreover, a realistic dynamic channel mea-sured in an indoor environment is reconstructed with the developed methodologies, and 95.6% PAS similar-ity can be achieved with 6 active probes. The satisfac- tory results demonstrate that the proposed algorithms are suitable for arbitrary channel emulation.