QoS-aware user association based on cell zooming for energy efficiency in cellular networks

In cellular networks, cell zooming with the variation of the traffic load is considered as one of promising technologies for energy saving. Cells with less traffic load can be turned into sleep mode and the other cells zoom in to ensure the coverage. In this paper, based on the cell zooming, we propose a quality of service (QoS) aware user association scheme (UAS) to reconfigure the cell association for energy saving. In the UAS, we consider the tradeoff between QoS guarantee and energy saving of the networks. The optimization problem of UAS is derived from the network weight matrix and user association matrix. A heuristic iteration algorithm is provided to solve this optimization problem, and then the cells without associated users can be turned off for energy saving. Simulation results show that the proposed UAS can significantly reduce energy consumption and improve the energy efficiency without degrading QoS, especially under the low traffic load.