Joint Multilayered User Clustering and Scheduling for 5G Advanced Ultra-dense RAN

In ultra-dense RAN consisting of a large number of distributed antennas, the coverage and the capacity can be improved by forming a number of user clusters (also called virtual small cells) with each cluster consisting of neighbor users and by executing cluster-wise small-scale MIMO in parallel using the same radio resource. However, a straightforward clustering produces a severe inter-cluster interference (ICI) and the capacity improvement is much smaller than expected. In this paper, we propose a joint multilayered user clustering and scheduling. This approach is based on user clustering using the user location information, user-cluster layering based on the interference-offset-distance (IOD), antenna assignment on each layer, simple layer-by-layer round-robin-type scheduling and cluster-wise MIMO. We evaluate by computer simulation the user capacity, the sum capacity, and the fairness to show the effectiveness of the proposed joint multilayered user clustering and scheduling.