Low-Complexity Mode Selection and Resource Allocation for Energy-Efficient D2D Communications

In this paper, the energy efficiency in a cellular network with device-to-device communications is studied. A mixed-integer max-min optimization problem is formulated with both mode selection and resource allocation. Since the optimal solution requires an exhaustive search, a low-complexity decomposition (LCD) method is derived. A fairness-aware mode selection scheme, a subcarrier assignment scheme, and a mode switching scheme are introduced and analyzed. Moreover, a novel power allocation scheme is proposed, which exploits the property of the fractional structure of the energy efficiency optimization problem over multiple subcarriers. The proposed LCD method is scalable and suitable for a large number of users and subcarriers. Simulation results demonstrate that our proposed LCD method achieves satisfactory energy efficiency performance and promotes the fairness among individual users.