Reduced Complexity Iterative Beamforming for a Set of Virtual MIMO Devices

In this paper, we develop a framework in which single antenna user equipment (UEs) can be clustered together, thus virtually forming a multi-antenna device. Since the antennas for a virtual device are located on different physical devices, applying previous beamforming methods requires the exchange of the channel state information (CSI) between the UEs within a virtual device which in turn induces a significant overhead. This paper shows how the iterative beamforming can be performed without sharing this CSI. Numerical results demonstrate that the performance loss due to this omission is insignificant.