Measurement Based Millimeter Wave Massive MIMO Channel Parameter Comparison

Massive multiple-input multiple-output (MIMO) plays a key role in millimeter wave (mmWave) communications. In this paper, a measurement campaign based on virtual antenna arrays is proposed to characterize indoor massive MIMO channel in mmWave band. Measurements have taken place in an empty hall environment and a rich scattering environment. Measurements are conducted using a virtual uniform rectangular array (URA) whose total elements are set to be $5\times 5,10\times 10$ and $20\times 20$ respectively at 28 GHz and 38 GHz with bandwidth of 4 GHz. The power angle delay profiles in each scenario are presented and channel characteristics are analyzed. MIMO metrics such as beam width, side lobe level and spatial resolution are compared with different array sizes and frequencies. Measurement results show that the beamwidth of the main lobe decreases with array size and central frequency, and therefore the resolution of multipath becomes higher.