Capacity and Robustness of Single- and Dual-Polarized MIMO Systems in Office and Industrial Indoor Environments

A study on the suitability of multiple-input multiple-output (MIMO) architectures employing either single- or dual-polarization antennas is presented, with the purpose of identifying not only which architecture provides better average capacity performance, but also which is more robust for avoiding low channel rank. It is expected that systems with high robustness will be required for MIMO in demanding industrial applications. A measurement campaign employing dual-polarized 8times8 patch arrays at 2.4 and 5.2 GHz is analyzed, where measurements were performed in two very distinct indoor scenarios: an office building and an industrial environment. For both environments the performance of three 4times4 subsystems (dual-polarized, vertical- polarized and horizontal-polarized) are compared in terms of the average capacities attained by these systems and their eigenvalue distributions. Average capacities are found to be only marginally different, indicating little advantage of dual-polarized elements for average performance. However, an eigenvalue analysis indicates that the dual-polarized system is most robust for full-rank MIMO communications, by providing orthogonal channels with more equal gain.