Energy-Efficient Switching ON/OFF Strategies Analysis for Dense Cellular Networks With Partial Conventional Base-Stations

Focusing on the energy efficiency (EE) improving problem in a densely deployed cellular network with partial conventional base stations (BSs) that cannot be frequently switched on/off, this paper jointly optimizes the switching on/off strategy and user association policy with the consideration of quality-of-service (QoS). By applying a modified switching cost model, we formulate the EE improving problem as an energy efficiency maximization problem (EEMP). To solve the EEMP efficiently, we first concentrate on the EEMP with a constant user distribution where switching cost is omitted temporarily, i.e., static- EEMP, and then the EEMP can be settled by using the results of the static-EEMP. After analyzing the hardness of solving the static-EEMP directly, several sub-optimal strategies are proposed for the static-EEMP to optimize the BSs working states and user association policy. With the results obtained from solving the static-EEMP, we propose a QoS First Maximum EE (QFMEE) scheme to solve the EEMP in two steps. In the first step, necessary BSs are switched on when the user distribution changes to ensure user QoS. In the second step, we judge the extra cost and the energy saving caused by the switching off operations to improve the network EE. Simulation results verify the effectiveness of our proposed strategies for static-EEMP and show that QFMEE can improve the network EE and reduce switching cost significantly when the switching cost occupies a considerable proportion in the total energy consumption.