A Holistic Approach for Lifetime Prolonging and Femto Base Station’s Sleeping Strategy in HetNets

While Femto Base Stations (FBSs) are promising solutions for providing the required throughput for end users, they may impact energy efficiency, especially, as the density of the FBSs increases significantly. In this paper we focus on enhancing energy efficiency in heterogenous networks, where Macro BSs (MBSs) and FBSs co-exist, by presenting a sleeping strategy. In the sleeping strategy FBSs serving few users are turned off and their users and resources are offloaded to neighboring FBSs. However, adapting the sleeping strategy will affect the lifetime of the FBSs, due to the frequent change of power level between turning ON and OFF the FBS. Therefore, in order to maximize energy savings, we formulate an optimization problem that provides an optimal user association and FBSs sleeping strategy for the entire network, while minimizing the total numbers of the power change for every FBS. Since the problem is NP-hard, we propose a clustering heuristic approach, where we divide the network into smaller clusters and solve the optimization for each cluster independently. Simulation results show that the clustering heuristic approach performs close to the optimal approach with the energy consumption being reduced significantly.