Energy-Efficient Resource Allocation for Full-Duplex Relay-Assisted D2D Communications

This paper investigates the resource allocation problem in full-duplex (FD) relay-assisted device-to-device (D2D) communications underlaying a multi-carrier cellular network. Under residual self-interference (SI), we aim to maximize the energy efficiency (EE) of D2D links via subcarrier assignment and power allocation while satisfying the quality of service (QoS) requirements of both D2D and cellular links. To solve the formulated EE maximization problem, we propose an iterative algorithm based on nonlinear fractional programming, where power allocation and subcarrier assignment are performed sequentially in each iteration, to handle the nonconvexity of the original problem. It is shown that the power allocation problem fits in D.C. (difference of two concave functions) programming while the subcarrier assignment corresponds to a job assignment problem whose optimal solution can be found in polynomial time. Finally, simulation results demonstrate that the proposed algorithm converges rapidly and achieves higher EE of D2D communications than existing schemes.