Millimeter-wave (mmWave) communication is considered to be one of the key enabler for higher throughput. However, the high path loss and the severe scattering make the mmWave difficult to reach to the receiver. To address issue, the usage of beamforming and the fast procedure to align beams between the transmitter and the receiver are necessary.
Although various studies on the faster beam alignment have been reported, most studies verify their benefit by simulations. Testbeds and field trials are very important steps towards the realization and approval of those concepts, but the practical implementation of the mmWave system testbed is another challenge due to new hardware constraints for ensuring a high frequency large bandwidth transmission and deploying large antenna arrays. In this context, it is necessary to reconcile between technologies of system hardware and signal processing algorithm to accomplish the successful mmWave beam management research.
Fig. 1. Pictures of the 28 GHz mmWave transmitter and receiver. The mmWave receiver is equipped to Jackal UGV, which enables the receiver to move.
For a demonstration of mmWave communication, we constructed 28 GHz mmWave testbed as in Fig. 1. At the transmitter, the signal generation starts from the baseband and the frequency of the baseband signal is uplifted to 28 GHz by the mixer and the local oscillator (LO). 16x4 uniform planar array (UPA) antenna radiates the 28 GHz signal. The receiver is equipped to Jackal unmanned ground vehicle (UGV) to reproduce the mobility of the user equipment, e.g., mobile phone and vehicle. Similar to the transmitter, the UPA antenna receives the 28 GHz signal, and the mixer and the LO down-convert the 28 GHz signal into the baseband signal. As shown in Fig. 2, the transmitter steers the beam towards the moving receiver. We are planning to implement the algorithm for faster beam alignment on the 28 GHz mmWave testbed and verify how much the algorithm impacts the real mmWave communication.