Power Control for Two-Way DF Relay-Aided Underlaid D2D Communications

Device-to-device (D2D) is used for direct communication between adjacent terminal devices and has been considered as one of the key technologies of 5G. However, when the distance between D2D users is far or the channel condition is poor, the effectiveness and reliability of transmission will be reduced. To solve this problem, a promising way is to use relay-aided D2D communication. In this paper, the minimum rate of a pair of D2D users is maximized by controlling the transmit power of D2D users and relay user while fulfilling the minimum rate requirement of the cellular link. The transmit power of each node is adjusted to minimize the useless power to obtain the optimal transmit power of D2D users and relay. The simulation results show that the minimum rate of a pair of D2D users reaches the maximum under the optimal power allocation scheme.