Energy-Efficient BS Switching-Off and Cell Topology Management for Macro/Femto Environments

International audienceIn the context of ever-increasing wireless data rates, energy consumption could increase fast, with severe consequences on the operator's energy bill, in addition to environmental considerations. Energy-efficient cell breathing and BS switching-off algorithms are an important tool for energy reduction in cellular networks. In this paper, an energy-effcient cell breathing and offoading mechanism in both macrocellular and heterogeneous networks is studied. First, the need for limiting the number of Macro-BSs switched off and the control of cell sizes are analyzed. An approach based on the use of a traffic threshold from a technique previously proposed by our team is applied in order to control the BS switching-off aggressiveness. One reason for limiting this aggressiveness is the trade-off we point out between the existing RAN power consumption and the transmission power in uplink for mobile devices. Then, in the context of macro/femto deployments, the BS switching-off possibilities are extended by means of the extra capacity from an added femtolayer under regulated control access. We explore the impact of access policies from 3GPP CSGs (Closed Subscriber Groups) on the network performance and how CSG features may be used by operators to set aspects such as pricing policies and QoS provision levels. In this article, our goal is to provide a combined approach of both techniques in a single framework for macro/femto environments. The obtained results are analyzed showing the importance of proper tuning of energy-efficient algorithms in order to guarantee convenient energy savings and maintaining good QoS levels