Iterative Power Allocation and Access Point Scheduling in Uplink Cell-Free Massive MIMO Systems

Abstract

One of the major bottlenecks that hinders the deployment of Cell-free (CF) massive Multiple-Input Multiple-Output (MINIO) in a cost-effective way is the limited capacity of back/front-haul connections. In this case, the traffic between the large number of distributed access points (APs) and the central processing unit can easily explode. Expensive point-to-point fronthauling technologies are certainly not desirable hence a shared fronthaul medium should be foreseen wherein (a subset of) APs share the same bandwidth-limited medium. However, the point-to-multipoint architectures require proper AP scheduling. In this paper, we propose a novel unified optimization framework for iterative power control and Al' scheduling in the uplink of the cell-free massive MIMO system, that offers a systematic user-centric solution towards scalable CF massive MIMO. The experimental results show that power control is not sufficient to reach the best minimum throughput and, therefore, an appropriate association of the users to the APs is crucial to improve the overall system performance.