Massive MIMO functionality splits based on hybrid analog-digital precoding in a C-RAN architecture

Cloud RAN is a promising enabler for distributed massive MIMO systems, yet is vulnerable to its fronthaul congestion. We propose an analog beamformer design in pursuit of maximizing multi-user sum average data rate. Each element of the analog beamformer is constructed based on a weighted sum of spatial channel covariance matrices. A regularized zero-forcing digital beamformer is based on the instantaneous effective channel information observed through the given analog beamformer. The effectiveness of the proposed hybrid precoding algorithm is validated by simulation.