Robustness of Distributed Multi-User Beamforming: An Experimental Evaluation

In this paper, we study the robustness of distributed beamforming in the presence of hardware imperfections. In particular, we characterize the impact of carrier frequency offset (CFO) between distributed antennas on multi-user receive beamforming. We characterize the performance of distributed beamforming in the presence of CFO using a massive MIMO platform. Using datasets collected from the platform, we measure and compare the beamforming performance in the presence and absence of CFO. Further, we study the effect of variation in CFO among beamforming antennas on the performance through simulations. Interestingly, we observe that this drop in performance is higher as more distributed antennas are included in beamforming. Our results can be used to determine the optimal number of antennas in distributed beamforming systems.