Power Allocation for Full-Duplex Relaying-Based D2D Communication Underlaying Cellular Networks

Device-to-device (D2D) communications allow direct transmissions between two proximate user equipments (UEs), which can improve local services in cellular networks. Considering full-duplex (FD) relaying can achieve higher spectrum and energy efficiency than half-duplex (HD) relaying, we propose a new D2D communication scheme that allows D2D links to underlay cellular downlink by assigning D2D transmitters as FD relays to assist cellular downlink transmissions. The system objective is to optimize the achievable rates for the D2D users while fulfilling the minimum rate requirements of the cellular users. To this end, we first derive the achievable rates for both the D2D users and the cellular users. Then we accomplish the system target by optimizing the transmission powers at the base station (BS) and at the D2D transmitter. Under the aggregate power constraint, we can solve the optimal power-allocation problem in closed form. The simulation results show that the proposed FD relaying-based D2D communication scheme outperforms the traditional cellular communication mode and the existing HD relaying-based D2D communication scheme in the maximal achievable rate.