User-cooperation scheme based on clustering for energy efficiency in cellular networks with D2D communication

In cellular networks, proximity users may directly communicate with each other without going through the base station. That is called Device-to-Device (D2D) communication. It has the advantages of improving the spectral efficiency and the power saving of a user equipment (UE). In D2D communication of cellular networks, multiple UEs work together to improve the overall throughput. We call this strategy user-cooperation. User-cooperation is useful method for multiple UEs using the same contents with the high data rate because they are capable of sharing information each other. However, these contents demand the high transmit power for a UE in uplink channel. Therefore, we study user-cooperation schemes based on clustering to minimize the average power consumption of UEs while guaranteeing the high data rate. In this paper, we develop an optimization problem that finds the optimal radius of the cluster to minimize the average power consumption of UEs. Numerical and simulation results show that user-cooperation of the proposed scheme can reduce a large amount of the average power consumption of a UE.