Joint Mode Selection and Resource Allocation for Relay-Based D2D Communications

This letter studies the joint mode selection, resource group (RG) assignment, and power allocation for D2D underlaid cellular communication systems. We formulate a resource allocation problem, which aims at maximizing the system sum rate of all D2D and cellular links while guaranteeing the required minimum rates of cellular and D2D links. To solve this problem, we first characterize the optimal power allocation when a D2D link operates in the direct or relay mode. Then, using these power allocation results, the joint mode selection and RG assignment can be formulated as a job assignment problem whose optimal solution can be obtained in polynomial time. Numerical results demonstrate that the proposed design significantly outperforms conventional schemes.