This paper presents some results of an experimental trial for the 5th generation (5G) wireless communication systems using 28GHz band. In order to tackle rapidly increasing traffic for 2020 and beyond, new radio access networks for the 5G mobile communication systems will introduce the use of higher frequency bands such as spectra higher than 10GHz to achieve higher capacity and super high bit rate transmission of several tens of Gbps. The target of this experimental trial is to evaluate the feasibility of using the 28GHz band with super-wide bandwidth of 800MHz for 5G wireless communication systems. To compensate large path-loss in higher frequency, the beamforming (BF) based on Massive multiple-input multiple-output (MIMO) is one of promising techniques and can be combined with spatial multiplexing of multiple data streams to achieve much higher capacity. In addition, to support the mobility of mobile station (MS), beam tracking technique is important. In this trial, we first conduct a basic experiment of single-stream transmission by using prototype system with base station (BS) having 96-element antenna and MS having 8-element antenna to evaluate the effectiveness of joint transmitter/receiver BF in 28GHz band in terms of coverage, impact of path loss, shadowing loss and penetration loss under indoor, outdoor and outdoor-to-indoor (O-to-I) environments. We show that by using 28 GHz band with BF based on Massive MIMO, higher throughput near 1.2Gbps can be achieved at many points in the indoor environment. It is also shown that the throughput of over 1Gbps can be achieved at points around 200m distant from BS in outdoor line-of-site (LOS) environment. Secondly, to evaluate the effectiveness of spatial multiplexing and beam tracking under more realistic environment, we also conduct the outdoor experiment of BF combined with 2-stream spatial multiplexing in high mobility environment with MS speed of up to 60km/h by using smartphone-shape MS antenna. We also show that maximum throughput of 3.77Gbps can be achieved with MS speed of 60km/h by using BF with 2-stream multiplexing and beam tracking.