Energy Efficient Sleep Mode Activation Scheme for Small Cell Networks

Abstract

Small cells deployed over the existing macrocell network reduce the access distance and thus offer an energy-efficient solution to provide high data rate coverage. However, dense deployment of small cells may cause energy waste under low load conditions. To cope with this issue, power saving techniques for small cell networks need to be carefully investigated. Invoking a sleep mode is one of the most promising techniques, which allows a small cell base station (SBS) without active users to enter a low power mode and switch to an active mode when required. When a user is within the coverages of several SBSs, the SBS with the best channel condition should be activated by comparing the channel fading from different SBSs to the user. Selecting the right SBS for an active user is challenging because the sleeping SBSs do not send or receive radio frequency signals for channel estimations. In this paper, we propose an energy efficient sleep mode activation scheme for small cell networks, in which the core network activates the sleeping SBS with the smallest large-scale channel fading to the active user. This scheme makes use of channel measurements in advance and adopts spacial interpolation to estimate the large-scale channel fading from sleeping SBSs to the active user. Simulation results show that the spacial interpolation can effectively estimate the large- scale channel fading, and the proposed sleep activation scheme can effectively save transmit power and hence improve the overall network energy- efficiency.