Practical Demonstration of Limited Feedback Beamforming for mmWave Systems

This paper presents a practical demonstration of the benefits of limited feedback beamforming for mmWave applications. Different beamforming strategies are presented, analysed and compared. Compressive sensing (CS) is investigated to accurately estimate the sparse Power Angular Profile (PAP) of the mmWave channel. This information is then used to estimate the antenna array weights required to steer the beam to maximise received SNR. This scheme is particularly attractive for outdoor mmWave networks where large antenna arrays are necessary to mitigate high observed pathloss. Codebook based beamforming strategies are also analysed. Using a practical mmWave antenna away, measurements are reported for a controlled multipath channel that compare the performance of the proposed beamforming strategies. In terms of received SNR CS based beamforming was shown to outperform more traditional codebook based solutions by to 5dB.