Energy Efficient Base Station On/Off with User Association under C/U Split

The mobile traffic explosion leads to dense deployed heterogeneous networks that can support peak time traffic. However, the utilization of base stations (BSs) is very inefficient during off-peak time due to the traditional strategy, which associates users with BSs based only on the received signal power. In this paper, we investigate the problem and design the joint cell switching-on/off with user association to maximize the network EE. During modeling the optimization problem, we consider the quality-of-service requirements of users and inter-cell interferences under the control plane (CP) and user plane (UP) split. The constraints between the CP and UP are considered. Since the optimization problem belongs to inter programming problem and is NP-hard, we propose a heuristic algorithm named DSUA, to maximize the system EE step by step. The DSUA algorithm deactivates the unnecessary BSs into sleep mode and constructs the user association with the active BSs. Simulation results show that the proposed algorithm can improve the network EE, especially in the light traffic load scenario.