RELISH: Green Multicell Clustering in Heterogeneous Networks with Shareable Caching

Energy saving in cellular systems is increasingly important due to the ever- deteriorating global warming. Heterogeneous networks (HetNets) can attain energy savings thanks to the lower operational and transmit power consumption of small base stations (BSs). To address inter-cell interference problem yet achieving network energy conservation, green multicell clustering facilitating BS sleeping and coordinated multipoint (CoMP) clustering paves a way toward future green HetNets. To further alleviate the backhaul power consumption induced by content requests from users, caching popular contents at BSs in a shareable manner is regarded as a viable solution. In this paper, we investigate the problem of green multicell clustering in HetNets with shareable caching (RELISH), and show its NP-hardness. By observing that BS sleeping plays a pivoting role in the RELISH problem, we propose the clustering- then-caching strategy to decompose the RELISH problem, and then design the dual- ascending clustering algorithm followed by the zero-replica caching algorithm for solving the sub-problems. The simulation results demonstrate that our proposed solution is effective in reducing total power consumption, and we also show how the power savings vary with system parameters.