A Fair Comparison of Virtual to Full Antenna Array Measurements

Abstract

Massive multiple-input multiple-output (MIMO) channel measurements are often obtained using virtual antenna arrays for complexity reasons. In this approach, a single antenna element is sequentially re-positioned to virtually form an antenna array in space. As a consequence, there are no mutual coupling effects when measuring with a virtual array. We perform realworld outdoor to indoor MIMO channel measurements with both, a virtual array approach and a full array approach, for various antenna spacings. From the obtained results, we observe that a spacing of a half-wavelength does not lead to the best match between the two approaches. We conclude that the deviation mainly originates from mutual coupling effects and quantify the difference in terms of error in channel gain.