Scalability and energy efficiency of Coordinated Scheduling in cellular networks towards 5G

Coordinated Scheduling (CS) is one of the main techniques to control inter-cell interference in present (4G) and future (5G) cellular networks. We show that coordination of a cluster of nodes can be formulated as an optimization problem, i.e., placing the Resource Blocks in each node's subframe with the least possible overlapping with neighboring nodes. We provide a clever formulation, which allow optimal solutions to be computed in clusters of ten nodes, and algorithms that compute good suboptimal solutions for clusters of several tens of nodes, fast enough for a network to respond to traffic changes in real time. This allows us to assess the relationship between the scale at which CS is performed and its benefits in terms of network energy efficiency and cell-edge user rate. Our results show that optimal CS allows a significant protection of cell-edge users. Moreover, this goes hand-in-hand with a significant reduction in the number of allocated Resource Blocks, which in turn allows an operator to reduce its energy consumption. Both benefits actually increase with the size of the clusters.