Power Control and Node Scheduling in Uplink Cell-free Massive MIMO with Centralized Beamforming

Fronthauling the traffic from/to large number of distributed access points (AP)s in the cell-free (CF) massive Multiple-Input Multiple-Output (MIMO) is one of the main challenges hindering the deployment of CF massive MIMO systems. As the point-to-point fronthaul architecture is not cost-effective, there is a need to move towards shared fronthaul mediums or a point-to-multipoint architecture that requires the proper user-AP scheduling to improve the overall performance while a constraint on the fronthaul bandwidth must also be respected. In this paper, a low-bandwidth system with centralized digital beamforming is considered and a novel algorithm is proposed for the joint power and AP scheduling problem. The proposed optimization framework provides a scalable solution for CF massive MIMO under stringent fronthaul bandwidth constraints.