Measurement-based massive MIMO channel characterization in subway station

In this paper, measurements of massive multiple-input and multiple-output (MIMO) radio channel are conducted in subway station scenarios. The measurements are conducted at the center frequency of 6 GHz with a bandwidth of 100 MHz. A virtual 64 × 4 planar antenna array is used at the transmitter (Tx), and a single antenna is placed at 34 different locations as the receiver (Rx). The typical channel characteristics are extracted, including channel gain, root mean square delay spread (RMS-DS), and K-factor. These results indicate that the spatial variations occur across the two-dimension (2D) large-scale antenna array. The variations are further investigated by modeling these features with respect to the distance between the Tx and the Rx. The results are useful for characterizing the non-stationary massive MIMO channels.