Joint Relay Selection and Resource Allocation for Relay-Assisted D2D Underlay Communications

Relay-assisted D2D (Device-to-device) communication as a supplement to direct D2D communications for enhancing LTE-A system capacity has been proposed. In this paper, a joint mode selection, relay selection and resource allocation optimization in relay-assisted D2D communications is addressed. We aim at maximizing the overall system throughput while guaranteeing the power limitations and signal-to-noise-and-interference ratios (SINR) requirements of all cellular and active D2D links. After decomposing the original design problem into two sub-problems: 1) Optimal Power Allocation (OPA); 2) Joint Mode selection, Relay selection and Channel allocation (JMRC), we then propose the corresponding algorithms to solve them sequentially. Simulation results show that our proposed scheme significantly outperforms the existing schemes.