Low-complexity energy-efficient mode selection and resource management for D2D communications

Mode selection among direct-idle mode, relay-idle mode and direct-reuse mode and resource management including resource block (RB) assignment and power control are two important research aspects related to the effectiveness of device-to-device (D2D) transmission in cellular networks. To maximize the overall system energy efficiency (EE) while guaranteeing the rate of both D2D and cellular links, this work takes both of them into consideration and develops a low-complexity two-step scheme. In the first step, considering the influence of the number of idle RBs, the mode selection and RB assignment are performed jointly by assuming the maximum transmit power usage. And then, the transmit power of each user is optimized based on the obtained mode selection and RB assignment. Specifically, to accomplish efficient and low-complexity power control, a noncooperative game based scheme is proposed for the users suffering from interference caused by RB reuse. Simulations are done and results show that the system EE can be significantly improved by the proposed low-complexity mode selection and RB assignment algorithm and the power control scheme.