Power Adaptation for Full-Duplex Relay-Aided D2D Communications with Direct Link

Full duplex, cooperative communications and device to device (D2D) communications are considered as key technologies for 5G mobile networks. In this paper, an optimum power allocation for full-duplex(FD) relaying aided D2D communications in underlaying mode is derived. The D2D transmitters act as FD relays to assist cellular downlink transmissions. Both amplify-and-forward and decode- and forward relay protocols are considered. The objective is to maximize the achievable rate for the D2D receiver while fulfilling the minimum rate requirements of the cellular user. Optimization technique is used to reduce the self interference resulted from the full-duplex mode.