  In this article, we present a real-time three dimensional (3D) hybrid
beamforming for fifth generation (5G) wireless networks. One of the key
concepts in 5G cellular systems is the small cell network, which settles the
high mobile traffic demand and provides uniform user-experienced data rates.
The overall capacity of the small cell network can be enhanced with the
enabling technology of 3D hybrid beamforming. This study validates the
feasibility of the 3D hybrid beamforming, mostly for link-level performances,
through the implementation of a realtime testbed using a software-defined radio
(SDR) platform and fabricated antenna array. Based on the measured data, we
also investigate system-level performances to verify the gain of the proposed
smart small cell system over long term evolution (LTE) systems by performing
system-level simulations based on a 3D ray-tracing tool.
