Power allocation optimization for D2D communication underlaying cognitive full duplex relay networks

This paper investigates the joint use of full-duplex relay (FDR) and Device-to-Device (D2D) communication in cognitive wireless networks (CWNs). FDR not only increases the time-frequency efficiency by the time-frequency reuse compared to half-duplex relay (HDR), but also expands the network coverage by the use of the relay. In addition, D2D can enhance the wireless resource efficiency and achieve high data rates and network throughput. In the paper, we use jointly D2D and FDR to propose a new CWN model, in which the D2D link underlays the FDR link in secondary networks and D2D transmitter is arranged as a FDR node to assist the transmission between secondary users. Then we optimize the rates of the D2D link, namely improve the secondary network throughput by the transmission powers allocation of the secondary transmitter and the FDR node in the case that the good FDR link communication situation in secondary networks is guaranteed and the secondary network doesn't interfere the primary network. The simulation results demonstrate that the proposed D2D communication underlaying cognitive full-duplex relay network outperforms the traditional CWNs and ones applying HDR and D2D in the secondary network throughput.