Experimental study on elevation directional channel properties to evaluate performance of 3d-mimo at base station in microcell outdoor to indoor environment

3D-MIMO, which utilizes 2D array antennas with vertical and horizontal elements, has drawn much attention for its ability to increase the capacity of mobile communication systems. The channel properties of azimuth direction have been investigated; however these of the elevation direction have not been reported enough. We therefore investigate elevation directional channel properties at a base station (BS) in a microcell outdoor-to-indoor (O2I) environment based on measurement results using a vector channel sounder. Specifically, we study the properties of the elevation angular spread (ESD) and mean Elevation angle of Departure (EoD). The results clarify the following: (1) the mean EoD and line-of-sight (LOS) angle have similar tendencies; however, the mean EoD has an offset from the LOS angle toward the ground, and (2) the ESD tends to increase as the distance between the BS and mobile station (MS) decreases and the MS antenna height increases.