Achieving green LTE-A HetNets with D2D traffic offload and renewable energy powered small cell BSs

Energy aware coordination between mobile devices and the cellular network infrastructure is studied. The objective is to rely on both device-to-device (D2D) communications and any small cell base stations (BSs) that can be powered by renewable energy in order to offload traffic from the mains powered macrocell BSs (MBSs) and small cell BSs (SCBSs) in a heterogeneous network (HetNet). This would allow putting a certain number of BSs in sleep mode, thus leading to energy savings. However, this should not come at the expense of increased energy consumption at the mobile terminals (MTs). Therefore, a suitable utility function that balances the roles of both the MTs using D2D and the cellular BSs is derived and used in an energy minimization algorithm implemented within the framework of state-of-the-art LTE-Advanced (LTE-A) cellular networks. Simulation results show significant energy savings in the network, in addition to savings for the mobile devices, without compromising their quality of service (QoS).