A cross-layer optimization of the joint macro- and picocell deployment with sleep mode for green communications

Picocells are viewed as a promising option to provide high-data-rate services and improve coverage in wireless communication systems. As traffic load increases, picocells are deployed rapidly, which may cause an energy consumption explosion. Nowadays, base station (BS) sleeping technique becomes a hot topic to save energy in cellular systems. In this paper, we aim to analyze the energy efficiency when sleeping mode is introduced into a heterogeneous system with macro- and picocells. A cross-layer optimization problem is formulated to find the optimal operation mode of this system (the active set of cells, and the access BS selection for each user). We proved that this problem is an NP-hard problem and an operation mode decision algorithm is developed to get the sub-optimal solution. Simulation results show significant energy reduction by introducing the proposed algorithm into heterogeneous system.