Green/Energy-Efficient Design for D2D

Device-to-device (D2D) communications, which facilitates direct transmissions between proximate devices, is one of the key enabling technologies for 5G communications. A mobile device commonly carries a limited energy supply, and it is thus critical to develop energy-efficient D2D communications. This article provides a discourse on how to improve energy efficiency in D2D communications via proper bandwidth and power allocation and how to leverage green energy harvesting and dual-battery architecture to enhance self-sustainability of devices. With the introduction of green energy-powered devices, a green relay assignment scheme is used to leverage the green relay devices to assist dual-hop D2D communications. This article also elicits the important role of mobile edge computing (MEC) in enabling D2D communications in which cloudlets in MEC may provide essential computing resources for the cellular base stations to jointly consider the channel state information among the devices, multihop routing path and bandwidth allocation to efficiently facilitate D2D communications.