Cell sizing based energy optimization in joint macro-femto deployments via sleep activation

In this paper, we investigate the optimal solution of power savings for femtocell cluster deployments in the sleep mode involved macro-femto two-tier scenarios. The proposed scheme aims at achieving high SINR with optimal transmit power of femto access point (FAP) by coordinating downlink cross-tier interference and intra-interference with utility and traffic based power control (UTPC) when macro base station (MBS) is under sleep activation. Since the optimal radius of femtocells can be obtained according to dynamic coverage extension, several sleep patterns can be defined for open access permitted hybrid femtocells. In this case, more FAPs can be switched into sleep mode and managed by the main active FAPs in the cluster. As a result, the number of active femtocells can be controlled in accordance with dynamic cell configurations, which can effectively reduce the energy impact of the femtocell cluster. The simulation results show that our proposed scheme enable positive influence on power efficiency and interference coordination for femtocell cluster in the two-tier heterogeneous networks, especially during the night zone.